,,am]ican ,,society ,,( ,,civil ,,eng9e]s ,,in/itut$ #aheb ,,transactions ,pap] ,no4 #aagd ,,pressure1 ,,resi/ance1 ,,& ,,/ability ,,( ,,e>?4,a ,,by ,j4,c4 ,,meem1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 ,,) ,,discussion ,,by ,,messrs4 ,t4 ,,k5n>d ,,?omson1 ,,*>les ,e4 ,,gregory1 ,,francis ,w4 ,,p]ry1 ,e4,p4 ,,goodri*1 ,,francis ,l4 ,,pruyn1 ,,frank ,h4 ,,c>t]1 ,,& ,j4,c4 ,,meem4 ,9 ! f9al discussion ( ! writ]'s pap]1 ,! ,brac+ ( ,tr5*es & ,tunnels1 ,) ,practical ,=mulas = ,e>? ,pressures1,b c]ta9 m9or exp]im5ts 7 not$ 9 connection ) ! ar*+ prop]ties ( s&4 ,9 ! pres5t pap] x is propos$ to take up aga9 ! "q ( e>? pressures1 b 9 m detail1 & to note "s fur!r exp]im5ts & d$uctions !refrom1 & also to consid] ! resi/ance & /ability ( e>? z appli$ to pil+ & f\ndations1 & ! pressure on & buoyancy ( subaque\s /ructures 9 s(t gr\nd4 ,9 ord] to make ?is pap] complete 9 itself1 x w be necess>y1 9 "s in/ances1 to include 9 sub/ance "s ( ! matt] ( ! =m] pap]1 & indulg5ce is ask$ f ^? read]s :o may note ?is fact4 ,illu/ration3 ,,fig4 #a4 ,,sections ,,( ,,box-,,frame ,,= ,,s&-,,ar* ,,exp]im5t ,exp]im5t ,no4 #a4--;,z ! s&-box exp]im5ts describ$ 9 ! =m] pap] 7 on a small scale1 exception might be tak5 to !m1 & !re=e ! writ] has made ?is exp]im5t on a scale suffici5tly l>ge to be mu* m conclusive4 ,z %[n 9 ,fig4 #a1 wood5 abutm5ts1 #c ft4 wide1 #c ft4 ap>t1 & ab\t #a ft4 high1 7 built & fill$ solidly ) s&4 ,wood5 walls1 #c ft4 ap>t & #d ft4 high1 7 !n built cross+ ! abutm5ts1 & solidly cleat$ & brac$ frames 7 plac$ across _! ends ab\t #b ft4 back ( ea* abutm5t4 ,a false bottom1 made to slide freely up & d[n betwe5 ! abutm5ts1 & project+ slightly beyond ! walls on ea* side1 0 !n block$ up snugly to ! bottom edges ( ! sides1 ?us obta9+ a box #c by #d by #g ft41 ! la/ dim5sion n be+ important4 ,bolts1 #dd 94 long1 ) long ?reads1 7 run up ?r\gh ! false bottom & ?r\gh #f by #ae by #b-;94 p9e wa%]s to nuts on ! top4 ,! box 0 fill$ ) ord9>y co>se s& f ! tr5*1 ! s& be+ compact$ z ?or\ghly z possible4 ,! ends 7 tight5$ d[n on ! wa%]s1 :i* 9 turn bore on ! compact$ s&4 ,! block+ 0 !n knock$ out f "u ! false bottom1 & ! foll[+ 0 not$3 ,z soon z ! block+ 0 remov$ ! bottom settl$ ne>ly #b 941 z not$ 9 ,fig4 #a1 ,plate ,,xxiv1 due to ! initial compact+ ( ! s& "u ! ar*+ /resses4 ,a measurem5t 0 tak5 f ! bottom ( ! wa%]s to ! top ( ! false bottom1 & x 0 not$ z #da 94 7,fig4 #a74 ,aft] "s ?ree or f\r h\rs1 z ! ar* _h n be5 brok51 x 0 decid$ to te/ x "u great] load+1 & f\r m5 7 plac$ on x1 f\r o!rs /&+ on ! haun*es1 z %[n 9 ,fig4 #b1 ,plate ,,xxiv4 ,"u ?is additional load+ ( ab\t #fjj lb4 ! bottom settl$ #b 94 m1 or ne>ly #d 94 9 all1 due to ! fur!r compression ( ! s& ar*4 ,ab\t an h\r aft] ! sup]impos$ load _h be5 remov$1 ! writ] jo/l$ ! box ) 8 foot suffici5tly to dislodge "s ( ! expos$ s&1 :5 ! ar* at once collaps$ & ! bottom fell to ! gr\nd4 ,ref]r+ to ,fig4 #b1 if1 in/ead ( be+ ord9>y s&1 ! block compris$ )9 ! area1 ,a ,u ,j ,v ,x1 _h be5 froz5 s&1 !re c be no reason to suppose t x w\ld n h su/a9$ itself1 =m+ a p]fect ar*1 ) all mat]ial remov$ bel[ ! l9e1 ,v ,e ,j1 9 fact1 ! freez+ process ( tunnel+ 9 s(t gr\nd is bas$ on ?is well-kn[n pr9ciple4 ,illu/ration3 ,,fig4 #b4 ,illu/ration3 ,,fig4 #c4 ,if1 !n1 in/ead ( remov+ ! mass1 ,j ,e ,v1 x is all[$ to rema9 & is support$ f ! mass above1 "o mu/ conc$e to ?is mass 9 its normal /ate ! same ar*+ prop]ties x w\ld h _h if froz51 except+1 ( c\rse1 t a great] ?ickness ( key %\ld be all[$1 to (fset a great] t5d5cy to compression 9 moi/ & dry z aga9/ froz5 s&1 :]e bo? are measur$ 9 a conf9$ area4 ,if1 9 ,fig4 #b1 ,e ,v ,j phi ! angle ( repose1 & x be assum$ t ,a ,j1 ! l9e bisect+ ! angle betwe5 t ( repose & ! p]p5dicul>1 measures at its int]section ) ! middle v]tical 7,a1 ,fig4 #b7 ! height :i* is necess>y to give a suffici5t ?ickness ( key1 x may be conclud$ t ?is s& ar* w be self-su/a9+4 ,t is1 x is assum$ t ! ar*+ effect is tak5 up virtually )9 ! limits ( ! area1 ,a ,n#a ,v ,e ,j ,n ,a1 ?us reliev+ ! /ructure bel[ ( ! /resses due to ! weight or ?ru/ ( any ( ! mat]ial above2 & t ! portion ( ! mat]ial bel[ ,v ,e ,j is probably dead weight on any /ructure und]nea?1 & :5 su/a9$ f bel[ =ms a natural c5t]+ = ! natural ar* above4 ,x is also probably true t ! mat]ial 9 ! areas1 ,x ,n#a ,a & ,a ,n ,u1 does n add to ! ar*+ /r5g?1 m especially 9 ^? mat]ials :]e cohesion may n be c\nt$ on z a factor4 ,?is is borne out by ! fact t1 9 ! exp]im5t not$1 a well-def9$ crack develop$ on ! surface ( ! s& at ab\t ! po9t ,u#a1 & ext5d$ app>5tly a consid]able dep?1 assum$ to be at ,n1 :]e ! haun* l9e is int]sect$ by ! slope l9e f ,a4 ,illu/ration3 ,,plate ,,xxiv1 ,,fig4 #a4--;,,initial ,,settlem5t ,,9 #c-;,,ft4 ,,s& ,,ar*1 ,,due ,,to ,,compression ,,( ,,mat]ial ,,on ,,remov+ ,,supports ,,f ,,bottom4 ,illu/ration3 ,,plate ,,xxiv1 ,,fig4 #b4--;,,f9al ,,settlem5t ,,( ,,s& ,,ar*1 ,,due ,,to ,,compression ,,9 ,,excess ,,load+4 ,9 ?is exp]im5t ! s& 0 good & %>p1 conta9+ "s gravel1 & 0 tak5 directly f ! adjo9+ excavation4 ,:5 ?r[n loosely 9 a heap1 x assum$ an angle ( repose ( ab\t #de degrees4 ,x %\ld be not$ t ?is mat]ial :5 te/$ 0 n compact$ z mu*1 nor did x possess ! same cohesion1 z s& 9 its normal undi/urb$ condition 9 a bank1 & = ?is reason x is believ$ t ! dep? ( key giv5 "h is absolutely safe = all except extraord9>y conditions1 su* z non-homog5e\s mat]ial & o!rs :i* may require special consid]ation4 ,ref]r+ aga9 to ! area1 ,a ,n#a ,v ,j ,n ,a1 ,fig4 #b1 x is probable t1 :ile self-su/a9+1 "s at lea/ ( ! l[] portion mu/ d]ive its initial support f ! c5t]+ bel[1 & ! writ] has made ! arbitr>y assumption t ! l[] half ( x is c>ri$ by ! /ructure :ile ! upp] half is entirely indep5d5t ( x1 &1 9 mak+ ?is assumption1 he believes he is add+ a factor ( safety !reto4 ,! area1 !n1 :i* is assum$ to be c>ri$ by an und]gr\nd /ructure ! dep? ( :i* is suffici5t to all[ ! l9es1 ,v ,a & ,j ,a1 to int]sect bel[ ! surface1 is ! l[] half ( ,a ,n#a ,v ,e ,j ,n ,a1 or its equival5t1 ,a ,v ,e ,j ,a1 plus ! area1 ,v ,e ,j1 or ,a ,v ,j ,a1 ! angle1 ,a ,v ,j1 be+ #a phi alpha --- 7 #ij - phi 7 phi #de -------4 #b #b ,x is n probable t ^! l9es ( ?ru/ or pressure transmission1 ,a ,n1 ,d ,k1 etc41 w be /raight1 b1 = purposes ( calculation1 !y w be assum$ to be s2 also1 t !y w act along & p>allel to ! l9es ( repose ( _! natural slope1 & t ! ?ru/ ( ! e>? w !re=e be measur$ by ! relation betwe5 ! radius & ! tang5t ( ?is angle multipli$ by ! weight ( mat]ial affect$4 ,! dead weight on a plane1 ,v ,j1 due to ! mat]ial above1 is1 !re=e1 :]e l span or extreme wid? ( op5+ ,v ,j1 ,w weight p] cubic foot ( mat]ial1 & ,w#a weight p] l9e> foot4 #b 7l _/ #b7 tan4 alpha ,w ,w#a ---------------------------------- #b #a _/ #a --- l tan4 --- 7#ij - phi7 phi ,w #b #b _/ l phi ----- tan4 7 #de ------- 7 ,w4 #b #b ,! application ( ! above to flat-ar*$ or circul> tunnels is v simple1 except t ! "q ( side ?ru/ %\ld be consid]$ also z a factor4 ,! ?ru/ aga9/ ! side ( a tunnel 9 dry s& hav+ a flat angle ( repose w necess>ily be great] ?an 9 v moi/ s& or clay1 :i* /&s at a mu* /eep] angle1 &1 = ! same reason1 ! ar* ?ru/ is great] 9 dry] s& & !re=e ! load on a tunnel /ructure %\ld n be z great1 ! mat]ial be+ compact & exclud+ cohesion z a factor4 ,?is c be illu/rat$ by ref]r+ to ,fig4 #c 9 :i* x is se5 t ! flatt] ! position ( ! rak]s key+ at ,w#a1 ,w#b1 & ,w1 ! great] w be ! side ?ru/ at ,a1 ,c1 & ,f4 ,x c also be illu/rat$ by assum+ t ! ar*+ mat]ial is compos$ ( cubes ( poli%$ m>ble set "o v]tically above ! o!r 9 close columns4 ,!re w\ld !n be absolutely no side ?ru/1 b1 likewise1 no ar*+ prop]ties w\ld be develop$1 & an indef9ite height w\ld probably be rea*$ above ! tunnel ro( be=e friction en\gh w\ld be develop$ to cause x to relieve ! /ructure ( any "p ( its load4 ,conv]sely1 if x be assum$ t ! sup]adjac5t mat]ial is compos$ ( l>ge b[l+ balls1 int]lock+ ) "s degree ( regul>ity1 x c be se5 t ^? above w =m !mselves into an ar* ov] ! c5t]+ made up ( ^? support$ directly by ! ro( ( ! /ructure1 ?us reliev+ ! /ructure ( any load except t due to ?is c5t]+4 ,if1 n[1 ! l9e1 ,a ,b1 9 ,fig4 #d1 be drawn s z to =m ) ,a ,c ! angle1 beta1 to be not$ lat]1 & x be assum$ t x measures ! area ( pressure aga9/ ,a ,c1 & if ! l9e1 ,c ,f1 be drawn1 =m+ ) ,c ,g1 ! angle1 alpha1 not$ above1 !n ,g ,f c be r$uc$ 9 "s measure by reason ( ! increase ( ,g ,c to ,c ,b1 because ! side ?ru/ above ! l9e1 ,b ,c1 has slightly dim9i%$ ! load+ above4 ,! writ] makes ! arbitr>y assumption t ?is decrease 9 ,g ,f %\ld equal #bj ( ,b ,c ,f ,d#a4 ,if1 !n1 ! l9e1 ,b ,d#a be drawn1 x is conc$$ t all ! mat]ial )9 ! area1 ,a ,b ,d#a ,g ,c ,a1 causes direct pressure aga9/ or ^u ! /ructure1 ,g ,c ,a1 ! v]tical l9es be+ ! ord9ates ( pressure due to weight1 & ! horizontal l9es 7qualifi$ by c]ta9 ratios7 be+ ! abscissas ( pressure due to ?ru/4 ,an extreme measurem5t ( ?is area ( pressure is d\btless approximately m ne>ly a curve ?an ! /raight l9es giv51 & ! curve1 ,a ,r ,t ,i ,d,,ii1 is !re=e drawn 9 to give graphically & approximately ! safe area ( :i* any v]tical ord9ate1 multipli$ by ! weight1 gives ! pressure on ! ro( at t po9t1 & any horizontal l9e1 or abscissa1 divid$ by ! tang5t ( ! angle ( repose & multipli$ by ! weight p] foot1 gives ! pressure on ! side at t po9t4 ,illu/ration3 ,,fig4 #d4 ,! practical conclusion ( ?is :ole assumption is t ! mat]ial 9 ! area1 ,f ,e ,c ,b ,b#a1 =ms ) ! equival5t opposite area an ar* react+ aga9/ ! face1 ,c ,b ,b#a & t1 z h]et(ore not$1 ! l[] half 7or its equival5t1 ,b ,d#a ,g ,b7 ( ! weight ( ?is is assum$ to be c>ri$ by ! /ructure1 ! upp] half be+ self-su/a9+1 z %[n by ! l9e1 ,b,,iii ,d,,iv 7or1 = absolute safety1 ! curv$ l9e71 & !re=e1 if rods c\ld be run f %eet+ inside ! tunnel area to a po9t outside ! l9e1 ,f ,b#a1 z indicat$ by ! l9es1 #e1 #f1 #g1 #h1 #aa1 #ab1 #ac1 etc41 t ! int]nal brac+ ( ?is tunnel c\ld be omitt$1 or t ! tunnel itself w\ld be reliev$ ( all load+1 :]eas ^! rods w\ld be c>ry+ "s l>ge portion at lea/ ( ! weight )9 ! area circumscrib$ by ! curve1 ,d,,ii ,i ,t ,g1 & fur!r1 t a tunnel /ructure ( ! approximate dim5sions %[n w\ld c>ry its maximum load ) ! surface ( ! gr\nd betwe5 ,d,,iv & ,f1 beyond :i* po9t ! pressure w\ld rema9 ! same = all dep?s4 ,9 calculat+ pressures on circul> ar*es1 ! ar*$ area %\ld fir/ be graphically resolv$ into a rectangul> equival5t1 z 9 ! "r half ( ,fig4 #d1 proce$+ subsequ5tly z not$4 ,! foll[+ in/ances are giv5 z p>tial evid5ce t 9 ord9>y gr\nd1 n subm]g$1 ! pressures d n exce$ 9 any in/ance ^? f\nd by ! above me?ods1 & x is v probable t simil> in/ances or exp]i5ces h be5 met by e eng9e] engag$ 9 s(t-gr\nd tunnel+3 ,9 build+ ! ,bay ,ridge tunnel sew]1 9 #fb;d & #fd? ,/reets1 ,brooklyn1 ! ar* timb] brac+ %[n 9 ,fig4 #a1 ,plate ,,xxvi1 0 us$ = m ?an #d1jjj ft41 or = two-?irds ( ! :ole #e1hjj ft4 call$ = 9 ! contract4 ,! ext]nal wid? ( op5+1 measur$ at ! wall-plate1 av]ag$ ab\t #ai ft4 = ! #ad-;ft4 circul> sew] & #ai ft4 = ! #ae-;ft4 sew]4 ,! ar* timb] segm5ts 9 ! cross-section 7 #aj by #ab-;94 ,nor? ,c>ol9a p9e ( good grade1 ) #b 94 (f ! butt = a be>+ to take up ! ?ru/4 ,!y 7 set #e ft4 ap>t on c5t]s1 & re/$ on #f by #ab-;94 wall-plates ( ! same mat]ial z not$ above4 ,! ultimate /r5g? ( ?is mat]ial1 across ! gra91 :5 dry & 9 good condition1 z giv5 by ! ,unit$ ,/ates ,=e/ry ,dep>tm5t te/s is ab\t #a1jjj lb4 9 compression4 ,"s te/s,c made 9 #aijg by ,mr4 ,e4,f4 ,%]man = ! ,*>les ,riv] ,dam 9 ,bo/on1 ,mass41 %[ t 9 yell[ p9e1 :i* _h be5 wat]-soak$ = two ye>s1 *ecks began to op5 at f #chh to #eha lb4 p] sq4 941 & t yields ( 94 7 not$ at f #fjj to #a1jjj lb4 ,z ! tunnel wall-plates describ$ 9 ?is pap] 7 subject to occasional saturation1 & always to a moi/ atmosph]e1 !y c\ld nev] h be5 consid]$ z equal to dry mat]ial4 ,_h ! full load+ %[n by ! =ego+ come on ^! wall-plates1 !y w\ld h be5 subject$ to a /ress ( ab\t #be tons ea*1 or ne>ly "o-half ( _! ultimate /r5g?4 ,9 only "o or two in/ances1 cov]+ /ret*es ( #ajj ft4 9 "o case & #bjj ft4 9 ano!r1 :]e !re 7 l>ge areas ( quicks& suffici5t to cause semi-aque\s pressure1 or pockets ( ! same mat]ial caus+ ecc5tric load+1 did ^! wall-plates %[ any signs ( heavy pressure1 & 9 _m in/ances !y 7 9 su* good condition t !y c\ld be tak5 out & us$ a second & a ?ird "t4 ,two especially int]e/+ in/ances came "u ! writ]'s obs]vation3 ,9 "o case1 due to a collapse ( ! int]nal brac+1 ! load ( an entire section1 #be ft4 long & #ai ft4 wide1 0 c>ri$ = sev]al h\rs on ribs spac$ #e ft4 ap>t4 ,! m9imum cross-section ( ^! ribs 0 #gc sq4 941 & !y 7 "u a /ress1 z not$ above1 ( #ej1jjj lb41 or ne>ly up to ! actual limit ( /r5g? ( ! wall-plate :]e ! rib bore on x4 ,:5 ^! wall-plates 7 exam9$1 aft] replac+ ! int]nal brac+1 !y did n appe> to h be5 "u any unusual /ress4 ,illu/ration3 ,,plate ,,xxv1 ,,fig4 #a4--,,normal ,,slopes ,,& ,,/rata ,,( ,,newly ,,excavat$ ,,banks4 ,illu/ration3 ,,plate ,,xxv1 ,,fig4 #b4--,,normal ,,slopes ,,& ,,/rata ,,( ,,newly ,,excavat$ ,,banks4 ,9 ano!r in/ance1 = a di/ance ( m ?an #gjj ft41 ! sub-grade ( ! sew] 0 #d ft4 bel[ ! level ( ! wat] 9 %>p s&4 ,9 excavat+ = bottoms ! wat] _h to be pump$ at ! rate ( m ?an #cjj gal4 p] m941 & x 0 necess>y to close-%eet a tr5* betwe5 ! wall-plates 9 :i* to place a section ( bottom4 ,9 spite ( ! utmo/ c>e1 "s gr\nd 0 necess>ily lo/1 & ?is 0 %[n by ! slight subsid5ce ( ! wall-plates & a loos5+ up ( ! w$ges 9 ! supports be>+ on ! ar* timb]s4 ,dur+ ?is op]ation ( bottom+1 two m5 on ea* side 7 con/antly employ$ 9 tight5+ up w$ges & %ims above ! ar* timb]s4 ,x is impossible to expla9 ! fact t ^! timb]s slack5$ 7)\t proportionate ro( settlem5t7 by any o!r !ory ?an t ! ar*+ 0 s ne>ly p]fect t x reliev$ ! brac+ ( a l>ge "p ( ! load1 ! ord9>y loose mat]ial be+ held 9 place by ! ar*+ or w$g+ toge!r ( ! #b-;94 by #c-;ft4 %eet+ bo>ds 9 ! ro(1 arrang$ 9 ! =m ( a segm5tal ar*4 ,! mat]ial above ?is ro( 0 co>se1 %>p s&1 ?r\gh :i* x _h be5 difficult to tunnel )\t los+ gr\nd1 & x _h admitt$ wat] freely aft] ea* ra9 until ! dra9age ( a neighbor+ pond _h be5 complet$1 ! m5 nev] be+ will+ to resume "w until ! influx ( wat] _h /opp$4 ,! =ego+ applies only to mat]ial ord9>ily f\nd "u gr\nd n subaque\s1 or :i* _c be class$ z aque\s or semi-aque\s mat]ial4 ,^! conditions w be not$ lat]4 ,illu/ration3 ,,fig4 #e4 ,illu/ration3 ,,fig4 #f4 ,! writ] w take up next ! "q ( pressures aga9/ ! faces ( %eet$ tr5*es or reta9+ walls1 9 mat]ial ( ! same "* z not$ above4 ,ref]r+ to ,fig4 #b1 x is n reasonable to suppose t hav+ pass$ ! l9e1 ,r ,f ,j1 ! "* ( ! /resses due to ! ?ru/ ( ! mat]ial w *ange1 if brac+ %\ld be sub/itut$ = ! mat]ial 9 ! area1 ,w ,v ,j ,r1 or if1 z 9 ,fig4 #c1 canvas is roll$ d[n along ! l9es1 ,e ,g & ,a ,o1 & if1 z ?is section is excavat$ betwe5 ! canvas faces1 tempor>y /ruts are erect$1 !re is no reason to believe t ) prop]ly adju/$ weights at ,w or ,w#b1 an exact equilibrium ( =ces & conditions _c be obta9$4 ,or1 aga91 if1 z 9 ,fig4 #e1 ! face1 ,p ,q1 is %eet$ & rodd$ back to ! surface1 key+ ! rods taut1 !re is und\bt$ly a /able condition & "o :i* c\ld n fail 9 !ory or practice1 nor c anyone1 look+ at ,fig4 #e1 d\bt t ! top timb]s are /ress$ m heavily ?an ^? at ! bottom4 ,! assumption is t ! t5d5cy ( ! mat]ial to slide t[>d ! toe causes x to w$ge itself betwe5 ! face ( ! %eet+ on ! "o h& & "s plane betwe5 ! %eet+ & ! plane ( repose on ! o!r1 & t ! resi/ance to ?is t5d5cy w cause an ar*+ ?ru/ to be develop$ along or p>allel to ! l9es1 ,a ,n1 ,b ,m1 etc41 ,fig4 #b1 :i* are assum$ to be ! l9es ( repose1 or curves approximat+ !reto4 ,z ! ?ru/ is greate/ 9 t mat]ial directly at ! face1 ,a ,o1 ,fig4 #f1 & is no?+ at ! plane ( repose1 ,c ,o1 x may be assum$ arbitr>ily t ! l9e1 ,b ,o1 bisect+ ?is angle divides ?is area into two1 9 "o ( :i* ! weight resolves itself :olly into ?ru/1 ! o!r be+ an area ( no ?ru/1 or :olly ( weight be>+ on ! plane ( repose4 ,call+ ?is l9e1 ,b ,o1 ! haun* l9e1 ! ?ru/ 9 ! area1 ,a ,o ,b1 is measur$ by its weight divid$ by ! tang5t ( ! angle1 ,p ,q ,r phi1 :i* is ! angle ( repose2 t is1 ! ?ru/ at any giv5 po9t1 ,r ,r ,q tan4 phi4 ,! writ] sugge/s t1 9 ^? mat]ials :i* h /eep] angles ( repose ?an #de1 ! area ( pressure may be calculat$ z above1 ! ?ru/ be+ comput$1 h[ev]1 z = an angle ( #de degrees4 ,9 calculat+ ! b5d+ mom5t aga9/ a wall or brac+1 !re is ! weight ( ! mass multipli$ by ! di/ance ( its c5t] ( gravity v]tically above ! toe1 or1 approximately3 #b ,area1 ,a ,o ,b weight p] unit --- height1 #c :]e h height1 ,w weight p] cubic foot ( mat]ial #ij lb41 #ij - phi & beta ------------- #b ,p pressure p] l9e> foot 7v]tically71 h #b !n ,p h ----- 7tan4 beta7 ,w --- h #b #c #a --- h#c ,w tan4 beta4 #c ,:5 ! angle ( repose1 phi1 is less ?an #de1 ?is result mu/ be r$uc$ by divid+ by tan4 phi2 t is1 #a h --- h#c tan4 beta tan4 phi4 #c ,figs4 #a & #b1 ,plate ,,xxv1 %[ rec5tly excavat$ banks ( gravel & s&1 :i*1 /&+ at a g5]al angle ( #de1 7 9 process ( work+1 t is1 !re 0 cont9ual slipp+ d[n ( p>ticles ( ! s&1 & x may be well to note t 9 "t1 "u exposure to wea!r conditions1 ^! banks w\ld f9ally assume a slope ( ab\t #cc degrees4 ,!y are typical1 h[ev]1 z %[+ ! normal slope ( fre%ly excavat$ s&y mat]ial1 & a slope :i* may be us$ 9 ord9>y calculations4 ,! /eps se5 9 ,plate ,,xxv %[ ! diff]5t *>act]i/ics ( gr\nd 9 close proximity4 ,9 ,fig4 #b1 ,plate ,,xxvi1,d may be se5 a typical bank ( gravel & s&2 x %[s ! well-def9$ slope ( s& adjac5t to & 9 connection ) ! cohesive prop]ties ( gravel4 ,! next po9ts to be consid]$ are ! m difficult problems conc]n+ subaque\s or saturat$ e>?s4 ,! writ] has made "s exp]im5ts :i* appe> to be conclusive1 %[+ t1 except 9 pure quicks& or :olly aque\s mat]ial1 z describ$ lat]1 ! e>? & wat] pressures act indep5d5tly ( ea* o!r4 ,= a bett] und]/&+ ( ! scope & purpose ( ?is pap]1 ! writ] divides sup]saturat$ or subaque\s mat]ials into ?ree classes3 ,class ,a4--,firm mat]ials1 su* z co>se & f9e gravels1 gravel & s&s mix$1 co>se s&s1 & f9e s&s 9 :i* !re is n a l>ge proportion ( f9e mat]ial1 su* z loam1 clay1 or pure quicks&4 ,class ,b4--,semi-aque\s mat]ials1 su* z f9e s&s 9 :i* !re is a l>ge proportion ( clay1 etc41 pure clays1 silts1 peats1 etc4 ,class ,c4--,aque\s mat]ials1 su* z pure quicks&s1 9 :i* ! solid matt] is s f9ely divid$ t x is amorph\s & virtually held 9 susp5sion1 oils1 quicksilv]1 etc4 ,"h x may be /at$ t ! t]m1 quicks&1 is s illusive t a true def9ition ( x is badly ne$$4 ,_m eng9e]s call quicks& any s& :i* fl[s "u ! influ5ce ( wat] 9 motion4 ,! writ] believes ! t]m %\ld be appli$ only to mat]ial s s\py t its prop]ties are practically ! same z wat] "u /atic conditions1 x be+ und]/ood t any mat]ial may be un/able "u ! influ5ce ( wat] at suffici5tly high velocities1 & t x is ) a /atic condition1 or "o approximately s1 t ?is pap] deals4 ,a cle> und]/&+ ( ! firm mat]ials not$ 9 ,class ,a w lead to a bett] solution ( problems deal+ ) ^? "u ,class ,b1 z x is to ?is ,class ,a t ! exp]im5ts l>gely relate4 ,! exp]im5ts not$ bel[ 7 made ) v>y+ mat]ial1 ?\gh ! pr9cipal type us$ 0 a f9e s&1 "u ! conditions 9 :i* x is ord9>ily f\nd 9 excavations1 ) less ?an #dj voids & less ?an #aj ( v f9e mat]ial4 ,illu/ration3 ,,fig4 #g4 ,exp]im5t ,no4 #b4--,! fir/ ( ^! exp]im5ts1 :i* 9 ?is s]ies w be call$ ,no4 #b1 0 simple1 & 0 made 9 ord] to %[ t ?is mat]ial does n fl[ readily "u ord9>y conditions1 :5 n c\pl$ ) ! dis*>ge ( wat] "u high velocity4 ,a bucket #ab 94 9 diamet]1 conta9+ ano!r bucket #i 94 9 diamet]1 0 us$4 ,a #f by #f-;94 hole 0 cut 9 ! bottom ( ! inn] bucket4 ,ab\t #c 94 ( s& 0 fir/ plac$ 9 ! bottom ( ! l>g] bucket & x 0 p>tly fill$ ) wat]4 ,! inside bucket 0 !n giv5 a false bottom & p>tly fill$ ) wet s&1 re/+ on ! s& 9 ! l>g] bucket4 ,bo? 7 fill$ ) wat]1 & ! weight1 ,w1 ,fig4 #g1 on ! arm 0 %ift$ until x balanc$ ! weight ( ! inside bucket 9 ! wat]1 ! di/ance ( ! weight1 ,w1 f ! pivot be+ not$4 ,! false bottom 0 !n remov$ & ! inside bucket1 re/+ on ! s& 9 ! l>g] "o1 0 p>tly fill$ ) s& & bo? 7 fill$ ) wat]1 ! conditions at ! po9t ( weigh+ be+ exactly ! same1 except t ! false bottom 0 remov$1 leav+ ! s& 9 contact ?r\gh ! #f by #f-;94 op5+4 ,x is readily se5 t1 if ! s& _h possess$ ! aque\s prop]ties sometimes attribut$ to s& "u wat]1 t 9 ! inside bucket w\ld h fl[$ out ?r\gh ! squ>e hole 9 ! bottom1 all[+ x to be lift$ by any weight 9 excess ( ! actual weight ( ! bucket1 less its buoyancy1 z w\ld be ! case if x conta9$ only wat] in/ead ( s& & wat]4 ,x 0 f\nd1 h[ev]1 t ! weight1 re/+ at a di/ance ( m ?an n9e-t5?s ( ! orig9al di/ance f ! pivot1 w\ld n raise ! inside bucket4 ,on lift+ ?is inside bucket bodily1 h[ev]1 ! wat] at once =c$ ! s& out ?r\gh ! bottom1 leav+ a hole almo/ exactly ! %ape & size ( ! bottom orifice1 z %[n 9 ,fig4 #a1 ,plate ,,xxvii4 ,x %\ld be /at$ t1 9 ea* case1 ! s& 0 put 9 9 small h&fuls & ?or\ghly mix$ ) wat]1 b n pack$1 & all[$ to /& = "s "t be=e ! exp]im5ts 7 tri$1 to insure ! compactness ( ord9>y conditions4 ,x is se5 f ,fig4 #a1 ,plate ,,xxvii1 t ! s& 0 /able en\gh to all[ ! bucket to be put on its side = ! mom5t ( be+ photograph$1 al?\gh x _h be5 pull$ out ( ! wat] a little less ?an #c m94 ,illu/ration3 ,,plate ,,xxvi1 ,,fig4 #a4--,,types ,,( ,,ar* ,,timb]s ,,us$ ,,9 ,,bay ,,ridge ,,tunnel ,,sew]4 ,illu/ration3 ,,plate ,,xxvi1 ,,fig4 #b4--,,normal ,,slope ,,( ,,loose ,,s&1 ,,gravel1 ,,& ,,cem5t$ ,,gravel1 ,,9 ,,close ,,proximity4 ,exp]im5t ,no4 #c4--;,9 ord] to %[ t ! ar*+ prop]ties ( s& are n de/roy$ "u subaque\s conditions1 a small s&-box1 hav+ a capacity ( ab\t #a cu4 ft41 & simil> to t describ$ 9 ,exp]im5t ,no4 #a1 0 made4 ,! bottom 0 cut out1 ) ! exception ( a -94 projection on two sides1 & a false bottom 0 plac$ bel[ & outside ( ! orig9al bottom1 ) bolts runn+ ?r\gh x1 key+ to wa%]s on top ( ! s&1 ) :i* ! box 0 p>tly fill$4 ,"o side ( ! box conta9$ a glass front1 9 ord] t conditions ( saturation c\ld be obs]v$4 ,! box ( s& 0 !n fill$ ) wat] &1 aft] saturation _h be5 complet$ & ! nuts & wa%]s _h be5 tight5$ d[n1 ! box 0 lift$ (f ! floor4 ,!re 0 f\nd to be no t5d5cy :atev] = ! bottom to fall away1 %[+ conclusively t ! ar*+ prop]ties _h n be5 de/roy$ by ! saturation ( ! s&4 ,! next ?ree exp]im5ts 7 int5d$ to %[ ! relative pressure ov] any giv5 area 9 contact ) ! wat] 9 ! "o case or s& & wat] 9 ! o!r4 ,illu/ration3 ,,fig4 #h4 ,exp]im5t ,no4 #d4--,! app>atus = ?is exp]im5t consi/$ ( a #c-;94 pipe ab\t #d-;94 long & connect$ ) a -94 goose-neck pipe #ag 94 high above ! top ( ! b[l %[n 9 ,fig4 #h & 9 ,fig4 #b1 ,plate ,,xxvii4 ,a loose rubb] valve 0 int5d$ to be seat$ on ! upp] face ( ! ma*9$ edge ( ! b[l & weight$ d[n suffici5tly to balance x aga9/ a head ( wat] correspond+ to ! #ag-;94 head 9 ! goose-neck4 ,! b[l 0 !n to be fill$ ) s& & ! diff]5ce1 if any1 not$ betwe5 ! weight requir$ to hold ! flap-valve d[n "u ! same head ( wat] fl[+ ?r\gh ! s&4 ,! results ( ?is exp]im5t 7 n conclusive1 ow+ to ! difficulty ( mak+ contact ov] ! :ole area ( ! s& & ! rim ( ! b[l at ! same "t4 ,at times1 = in/ance1 less ?an #a lb4 w\ld hold back ! wat] indef9itely1 :ile1 aga91 #b or #c lb4 w\ld be requir$ z oppos$ to ! #d lb4 approximate pressure requir$ to hold d[n ! cle> wat]4 ,aga91 at times ! wat] w\ld n fl[ ?r\gh ! neck at all1 ev5 aft] sev]al h\rs1 & aft] increas+ ! head by atta*+ a long] rubb] tube !reto4 ,9 view ( ^! conditions1 ?is exp]im5t w\ld n be not$ "h1 except t x unexpect$ly develop$ "o int]e/+ fact4 ,9 ord] to insure aga9/ a /oppage ( wat]1 z above ref]r$ to1 gravel 0 fir/ put into ! bottom ( ! b[l & ! flap-valve 0 !n rubb$ d[n & held tightly :ile ! pipe 0 fill$4 ,on be+ releas$1 ! pressure ( wat] inv>iably =c$ out ! :ole body ( s&1 z %[n 9 ,fig4 #b1 ,plate ,,xxvii4 ,c>e 0 tak5 to see t ! s& 0 saturat$ 9 ea* case1 & ! exp]im5t 0 repeat$ numb]less times1 & inv>iably ) ! same result4 ,! s& conta9$ ab\t #dj ( voids4 ,! d$uction f ?is exp]im5t is t ! pressure ( wat] is aga9/ r ?an ?r\gh s& & t any excess ( voids occurr+ adjac5t to a face aga9/ :i* !re is pressure ( wat] w be fill$ ) s&1 except+ 9 s f>1 ( c\rse1 z ! normal exi/+ voids all[ ! pressure ( ! wat] to be transmitt$ ?r\gh !m4 ,illu/ration3 ,,plate ,,xxvii1 ,,fig4 #a4--;,,exp]im5t ,,%[+ ,,prop]ties ,,( ,,s&4 ,illu/ration3 ,,plate ,,xxvii1 ,,fig4 #b4--,,s& ,,pu%$ ,,up ,,f ,,b[l ,,by ,,wat] ,,pressure ,,?r\gh ,,goose-,,neck4 ,if1 !n1 ! cov]+ ( s& ov] a /ructure is suffici5tly heavy to all[ ar*+ action to be set up1 ! /ructure aga9/ :i* ! pressure is appli$ mu/ be reliev$ ( mu* ( ! pressure ( wat] aga9/ ! area ( s& n con/itut$ z voids act+ outside ( ! ar*+ area4 ,?is is confirm$ by ! two foll[+ exp]im5ts3 ,exp]im5t ,no4 #e4--,! same app>atus 0 us$ "h z 9 ,exp]im5t ,no4 #b1 ,fig4 #g1 except t ! inside bucket _h a solid bottom4 ,! inside & outside buckets 7 fill$ ) wat] & ! po9t 0 not$ at :i* ! weight w\ld balance ! inside bucket at a po9t "s #c 94 (f ! bottom ( ! outside bucket4 ,?is po9t 0 measur$1 & ! bottom ( ! l>g] bucket 0 cov]$ ov] ) s& s t 9 sett+ solidly 9 ! s& ! inside bucket w\ld occupy ! same relative position z x did 9 ! wat]4 ,! same weight 0 !n appli$ & w\ld n beg9 to lift ! inn] bucket4 ,= in/ance1 9 ! fir/ "p ( ! exp]im5t ! weight /ood at #ab 94 f ! pivot1 :ile 9 ! next /ep ! weight1 /&+ at ! end ( ! b>1 _h no effect1 & consid]able ext]nal pressure _h to be ex]t$ be=e ! bucket c\ld be lift$4 ,imm$iately aft] x 0 reliev$1 h[ev]1 ! weight at #ab 94 w\ld hold x cle> ( ! s&4 ,no attempt 0 made to "w ! bucket into ! s&2 ! s& 0 level$ up & ! bucket 0 seat$ on x1 turn$ once or twice to insure contact1 & !n all[$ to /& = "s "t be=e mak+ ! exp]im5t4 ,no attempt 0 made to e/abli% ! relation%ip betwe5 s&s ( v>y+ voids1 ! g5]al fact only be+ e/abli%$1 by a suffici5t numb] ( exp]im5ts1 t ! weight requir$ to lift ! bucket 0 m ?an d\ble 9 s& hav+ #dj ( voids ?an t requir$ to lift ! bucket 9 wat] only4 ,illu/ration3 ,,fig4 #i4 ,exp]im5t ,no4 #f4--,! app>atus = ?is exp]im5t consi/$ ess5tially ( a hydraulic *amb] ab\t #h 94 9 diamet] & #a ft4 high1 ! top be+ removable & conta9+ a coll> ) suitable pack+1 ?r\gh :i* a #b-;94 pi/on mov$ freely up & d[n1 ! :ole be+ simil> to ! cyl9d] & pi/on ( a l>ge hydraulic jack1 z %[n 9 ,fig4 #a1 ,plate ,,xxviii4 ,j bel[ ! coll> & above ! *amb] !re 0 a -94 inlet lead+ to a copp] pipe & !nce to a high-pressure pump4 ,atta*$ to ?is !re 0 a gauge to %[ ! pressure obta9$ 9 ! *amb]1 all z %[n 9 ,fig4 #i4 ,! purpose ( ! app>atus 0 to te/ ! diff]5ce 9 pressure on any object subm]g$ 9 cle> wat] & on ! same object buri$ 9 ! s& "u wat]4 ,x is readily se5 t1 if pressure be appli$ to ! wat] 9 ?is *amb]1 ! am\nt ( pressure 7z measur$ by ! gauge7 necess>y to lift ! pi/on w be t due to ! weight ( ! pi/on1 less its displacem5t1 plus ! friction ( ! pi/on 9 ! coll>4 ,illu/ration3 ,,plate ,,xxviii1 ,,fig4 #a4--;,,app>atus ,,= ,,measur+ ,,loss ,,( ,,pressure ,,9 ,,subaque\s ,,mat]ials4 ,illu/ration3 ,,plate ,,xxviii1 ,,fig4 #b4--,,rais+ ,,ro( ,,( ,,batt]y ,,tubes1 ,,9 ,,brooklyn1 ,,by ,,ble$+ ,,s& ,,?r\gh ,,displac$ ,,plates4 ,n[1 if = any reason ! bottom area ( ! pi/on aga9/ :i* ! wat] pressure acts be r$uc$1 x w necess>ily require a proportionate am\nt ( increase 9 ! pressure to lift ?is pi/on4 ,if1 !re=e1 x is f\nd t #aj lb41 = illu/ration1 be requir$ to lift ! pi/on :5 plung$ 9 cle> wat]1 & #bj lb4 be requir$ to lift x :5 buri$ 9 s&1 x c be assum$ at once t ! area ( ! pi/on has be5 r$uc$ #ej by be+ buri$ 9 ! s&1 elim9at+ ! "q ( ! friction ( ! s& itself ar\nd ! pi/on4 ,9 ord] to det]m9e :at ?is friction might be1 ! writ] arrang$ a table /&+ on legs above ! bottom ( ! *amb]1 all[+ ! pi/on to move freely ?r\gh a hole 9 its c5t]4 ,?r\gh ?is table pipes 7 ent]$ 7z %[n 9 "p ( ,fig4 #i74 ,! :ole 0 !n plac$ 9 ! *amb] ) ! pi/on 9 place1 & ! area above 0 fill$ ) s& & wat]4 ,x is ?us se5 t1 ! end ( ! pi/on be+ free & 9 cle> wat]1 ! diff]5ce1 if any1 betwe5 ! pressure requir$ to lift ! pi/on :5 9 cle> wat] alone & 9 ! case ?us not$1 :]e x 0 surr\nd$ by s&1 w\ld measure ! friction ( ! s& on ! pi/on4 ,aft] sev]al trials ( ?is1 h[ev]1 x 0 cle>ly se5 t ! friction 0 too slight to be not$ accurately by a gauge regi/]+ s+le p\nds1 t is1 ) a pi/on 9 contact ) #f 94 ( s& v]tically1 a friction ( #be lb4 p] sq4 ft4 w\ld only require an increase ( #a4h lb4 on ! gauge4 ,x is !re=e assum$ t ! friction on s small a pi/on 9 s& ne$ n be consid]$ z a mat]ial factor 9 ! exp]im5ts made4 ,! pi/on 0 plung$ into cle> wat]1 & x 0 f\nd t ! pressure requir$ to lift x 0 ab\t #d lb4 ,! cap 0 !n tak5 (f1 a dep? ( ab\t #b 94 ( s& 0 plac$ 9 ! bottom ( ! *amb]1 & !n ! pi/on 0 set 9 place & surr\nd$ by s& to a dep? ( "s #f 941 wat] be+ add$ s t ! s& 0 completely saturat$4 ,?is 0 all[$ to /& until x _h rega9$ ! /ability ( ord9>y s& 9 place1 :]eupon ! cap ) ! coll> be>+ 0 set 9 place ov] ! pi/on1 ! ma*9e 0 c\pl$ up1 & ! pump 0 />t$4 ,a s]ies ( f\r exp]im5ts1 ext5d+ ov] a p]iod ( two or ?ree days1 gave ! foll[+ results3 ,te/ #a4--,! pi/on began to move at a pressure ( #be lb4 ,! pressure gradually dropp$ to #g lb41 at :i* po9t1 app>5tly1 x came out ( ! s&1 & cont9u$ at #g lb4 dur+ ! rema9d] ( ! te/4 ,te/ #b4--,! pi/on 0 plung$ back into ! s&1 )\t remov+ ! cap1 & all[$ to /& = ab\t #b h\rs4 ,no attempt 0 made to pack ! s& or to see its condition ar\nd ! pi/on1 x be+ presum$1 h[ev]1 t x _h reasonable "t to get a fair am\nt ( set4 ,at slightly above #bj lb4 ! pi/on began to move1 & z soon z a pocket ( wat] accumulat$ beh9d ! pi/on ! pressure imm$iately dropp$ to #i lb4 & cont9u$ at ?is po9t until x came out ( ! s&4 ,te/ #c4--,! pi/on 0 plung$ into ! s& & hamm]$ d[n )\t wait+ = ! s& to come to a def9ite set4 ,9 ?is case ! initial pressure %[n by ! gauge 0 #ag lb41 :i* imm$iately dropp$ to #h lb4 z soon z ! pi/on _h mov$ suffici5tly f> to all[ wat] to accumulate bel[ x4 ,te/ #d4--,! cap 0 aga9 remov$1 ! pi/on set up 9 place1 ! s& compact$ ar\nd x 9 approximately ! same condition x w\ld h _h if ! s& _h be5 9 place und]gr\nd2 ! cap 0 !n set 9 place &1 aft] an h\r1 ! pump 0 />t$4 ,! pressure regi/]$ 0 #be lb4 & ext5d$ ov] a p]iod ( sev]al seconds be=e !re 0 any movem5t 9 ! pi/on4 ,! pi/on respond$ f9ally )\t any increase ( pressure1 &1 aft] lift+ an in* or two1 ! pressure gradually dropp$ to #aj lb41 :]e x rema9$ until ! pi/on came out ( ! s&4 ,! sum & av]age ( ^! te/s %[s a relation ( #bb lb4 = ! pi/on 9 s& to ab\t #h lb4 z soon z ! volume ( wat] _h accumulat$ bel[ x1 :i* w\ld correspond v closely to a s& conta9+ #dj ( voids1 :i* 0 ! *>act]i/ic ( ! s& us$ 9 ?is exp]im5t4 ,! conclusions f ?is exp]im5t appe> to be absolutely f9al 9 illu/rat+ ! pressure due to wat] on a tunnel buri$ 9 s&1 ei!r on ! ar* above or on ! sides or bottom1 z well z ! buoyant effect ^u ! tunnel bottom "u ! same conditions4 ,:ile ! app>atus w\ld h to be design$ & built on a mu* l>g] scale 9 ord] to measure accurately ! pressures due to s&s & e>?s ( v>y+ *>act]i/ics1 x appe>s to be conclusive 9 %[+ ! pr9ciple1 & ne> en\gh to ! !oretical value to be tak5 = practical purposes 9 design+ /ructures aga9/ wat] pressures :5 buri$ 9 s& or e>?4 ,x %\ld be c>efully not$ t ! friction ( ! wat] ?r\gh s&1 :i* is always a l>ge factor 9 subaque\s con/ruction1 is virtually elim9at$ "h1 z ! wat] pressure has to be transmitt$ only "s #f or #h 94 to actuate ! base ( ! pi/on1 :]eas 9 a tunnel only half subm]g$ ?is di/ance might be z _m feet1 & w\ld be a consid]able factor4 ,x %\ld be not$ also t al?\gh ! area subject to pressure is dim9i%$1 ! pressure on ! area rema9+ corresponds to ! full hydro/atic head1 z w\ld be %[n by ! pressure on an air gauge requir$ to hold back ! wat]1 except1 ( c\rse1 z x may be dim9i%$ m or less by friction4 ,! writ] und]/&s t exp]im5ts ( a simil> nature & ) simil> app>atus h be5 tri$ on clays & peats ) results consid]ably high]2 t is1 9 "o case1 !re 0 a pressure ( #dj lb4 be=e ! pi/on />t$ to move4 ,! foll[+ is giv51 9 "p1 z an analysis & explanation ( ! above exp]im5ts & notes3 ,x is well kn[n t if lead be plac$ 9 a hydraulic press & subject$ to a suffici5t pressure x w exhibit prop]ties some:at simil> to s(t clay or quicks& "u pressure4 ,x w fl[ out ( an orifice or m ?an "o orifice at ! same pressure4 ,?is is due to ! fact t practically voids d n exi/ & t ! pressure is s great1 comp>$ ) ! molecul> cohesion1 t ! latt] is virtually nullifi$4 ,x is also !oretically true t solid /one "u inf9itely high pressure may be liquefi$4 ,if 9 ! cyl9d] ( a hydraulic press !re be put a c]ta9 quantity ( cobble/ones1 leav+ a cle>ance betwe5 ! top ( ! /one & ! pi/on1 & if ?is space1 toge!r ) ! voids1 be fill$ ) wat] & subject$ to a great pressure1 ! sides or ! walls ( ! cyl9d] are act$ on by two pressures1 "o almo/ negligible1 :]e !y are 9 contact ) ! /one1 re/ra9+ ! t5d5cy ( ! /one to roll or slide outw>d1 & ! o!r due to ! pressure ( ! wat] ov] ! area aga9/ :i* !re is no contact ( /one4 ,t ?is area ( contact %\ld be d$uct$ f ! pressure area c be cle>ly %[n by assum+ ano!r cyl9d] ) cross-/icks jamm$ into x1 z %[n 9 ,fig4 #aj4 ,a glance at ?is figure w %[ t !re is no aque\s pressure on ! walls ( ! cyl9d] ) :i* ! ends ( ! /icks come 9 contact & ! loss ( ! pressure aga9/ ! walls due to ?is is equal to ! lea/ sectional area ( ! /ick or tube ei!r at ! po9t ( contact or int]m$iate !reto4 ,foll[+ ?is reason+1 9 ,fig4 #aa x is f\nd t an equival5t area may be d$uct$ cov]+ ! lea/ area ( cont9u\s contact ( ! cobble/ones1 z %[n along ! dott$ l9es 9 ! "r half ( ! figure4 ,return+1 if1 :5 ! pressure is appli$1 an orifice be made 9 ! cyl9d]1 ! wat] w at once fl[ out "u pressure1 all[+ ! pi/on to come 9 contact ) ! cobble/ones4 ,if ! fl[ ( ! wat] 7 controll$1 s z to /op x at ! po9t :]e ! /one & wat] are bo? "u direct pressure1 x w\ld be f\nd t ! pressures 7 totally indep5d5t ( ea* o!r4 ,! aque\s pressure1 = in/ance1 w\ld be equal at e po9t1 :ile ! pressure on ! /one w\ld be ?r\gh & along ! l9es ( contact4 ,if ?is contact 0 reasonably well made & cov]$ #dj ( ! area1 "o w\ld expect ! /one1 indep5d5tly ( ! wat]1 to /& #dj ( ! pressure :i* a full area ( solid /one w\ld /&4 ,if ?is pressure %\ld be enorm\sly increas$ aft] exclud+ ! wat]1 x w\ld f9ally result 9 cru%+ ! /one into a solid mass2 & if ! pressure %\ld be increas$ indef9itely1 "s !oretical po9t w\ld be rea*$1 z above not$1 :]e ! /one w\ld ev5tually be liquefi$ & w\ld assume liquid prop]ties4 ,illu/ration3 ,,fig4 #aj4 ,illu/ration3 ,,fig4 #aa4 ,! same g5]al reason+ applies to pure s&1 s& be+ 9 effect cobble/ones 9 m9iature4 ,9 press+ ! pi/on d[n on dry s& x w be displac$ into e exi/+ abnormal void1 b w be displac$ into ^! voids r ?an press$ into !m1 9 ! true def9ition ( ! ^w1 & :ile x w\ld fl[ out ( an orifice 9 ! sides or bottom1 all[+ ! pi/on to be =c$ d[n z 9 a s&-jack1 x w\ld n fl[ out ( an orifice 9 ! top ( ! pi/on1 except "u pressures s abnormally high z to make ! mass !oretically aque\s4 ,if ! positions ( cyl9d] & pi/on be rev]s$1 ! pi/on po9t+ v]tically upw>d & ! s& bl$ into an orifice 9 or ?r\gh x1 ! void caus$ by ! outfl[ ( ?is s& w\ld be fill$ by s& displac$ by ! pi/on press+ upw>d r ?an by s& f above4 ,x 0 ! k ( ?is pr9ciple :i* enabl$ ! contractors to jack up successfully ! ro( ( a long section ( ! ca/-iron l9$ tubes "u ,joralemon ,/reet 9 ,brooklyn1 9 connection ) ! recon/ruction ( ! ,batt]y tubes at t po9t1 ! me?od ( op]ation1 z p>tly %[n 9 ,fig4 #b1 ,plate ,,xxviii1 be+ to cut ?r\gh a section ( ! ro(1 #d by #aj ft4 9 area1 ?r\gh :i* holes 7 drill$ & ?r\gh :i* aga9 ! s& 0 bl$1 heavy pressure be+ appli$ f bel[ ?r\gh ! m$ium ( hydraulic jacks4 ,by a c>eful manipulation ( bo? ^! op]ations1 sections ( ! ro( ( ! above dim5sions 7 ev5tually rais$ ! requir$ height ( #cj 94 & p]man5tly brac$ !re 9 a s+le %ift4 ,if wat] 9 excess be put into a cyl9d] conta9+ s&1 & pressure be appli$ !reto1 ! wat]1 if all[$ to fl[ out ( an orifice1 w c>ry ) x a c]ta9 quantity ( s&1 accord+ to ! velocity1 & ! obs]vation ( ?is might easily give rise to ! errone\s impression t ! s&1 z well z ! wat]1 0 fl[+ out "u pressure1 &1 z h]et(ore /at$1 has caus$ _m eng9e]s & contractors to apply ! t]m quicks& to any s& fl[+ ?r\gh an orifice ) wat]4 ,s& 9 its natural b$ always conta9s "s f9e mat]ial1 & :]e ?is is l>gely less ?an ! p]c5tage ( voids1 x has no mat]ial effect on ! pressure ex]t$ by ! s& ) or )\t wat]1 z above not$4 ,if1 h[ev]1 ?is f9e mat]ial be l>gely 9 excess ( ! voids1 x all[s great] initial compression to take place :5 dry1 & all[s to be set up a c]ta9 am\nt ( hydraulic action :5 saturat$4 ,if ! base ( ! mat]ial be s& & ! fill be s-call$ quicks& 9 excess ( ! voids1 pressure w cause ! quicks& to set up hydraulic action1 & ! action ( ! pi/on w appe> to be simil> to t ( a pi/on act+ on purely aque\s mat]ial4 ,j "h ! writ] desires to prote/ aga9/ consid]+ semi-aque\s masses1 su* z s\py s&s1 s(t concrete1 etc41 z ex]t+ hydro/atic pressure due to _! weight 9 bulk1 in/ead ( to ! specific gravity ( ! basic liquid4 ,= in/ance1 resort+ aga9 to ! illu/ration ( cubes & sph]es1 x may be assum$ t a cubical receptacle has be5 p>tly fill$ ) small cubes ( poli%$ m>ble1 pil$ v]tically 9 columns4 ,:5 ?is receptacle is fill$ ) liquid ar\nd ! piles ( cubes !re w be no pressure on ! sides except t due to ! hydro/atic pressure ( ! wat] at #fb lb4 ,! bottom1 h[ev]1 w resi/ a comb9$ pressure due to ! wat] & ! weight ( ! cubes4 ,aga91 assume t ! receptacle is fill$ ) small sph]es1 su* z m>bles1 & t wat] is !n p\r$ 94 ,! pressure due to ! weight ( ! solids on ! bottom is reliev$ by ! loss 9 weight ( ! m>bles due to ! wat]1 & also to ! t5d5cy ( ! m>bles to ar* ov] ! bottom1 & :ile ! pressure on ! sides is increas$ by ?is am\nt ( ?ru/1 ! aque\s pressure is /ill t ( a liquid at #fb lb41 & x is inconceivable t "s eng9e]s1 9 calculat+ ! ?ru/ ( aque\s masses1 speak ( x z a liquid weigh+1 say1 #abj or #aej lb4 p] cu4 ft42 z well might !y expect to an*or sph]ical copp] floats 9 front ( a bulkhead & expect ! hydro/atic pressure aga9/ ?is bulkhead to be dim9i%$ because ! actual volume & weight ( ! wat] directly 9 front ( ! bulkhead has be5 dim9i%$4 ,^? :o h _h exp]i5ce 9 ty+ n>r[ deep =ms = concrete ) small wires or bolts & quickly fill+ !m ) liquid concrete1 mu/ realize t no su* pressures are ev] develop$ z w\ld correspond to liquids ( #aej lb4 p] cu4 ft4 ,if ! solid mat]ial 9 any liquid is agitat$1 s t x is virtually 9 susp5sion1 x _c add to ! pressure1 & if all[$ to subside x acts z a solid1 indep5d5tly ( ! wat] conta9$ ) x1 al?\gh ! wat] may *ange some:at ! prop]ties ( ! mat]ial1 by increas+ or *ang+ its cohesion1 angle ( repose1 etc4 ,t is1 9 sub/ance1 ^? p>ticles :i* re/ solidly on ! bottom & are 9 contact to ! top ( ! solid mat]ial1 d n d]ive any buoyancy f ! wat]1 :ile ^? p>ticles n 9 contact ) ! bottom directly or ?r\gh o!r p>ticles1 lose j s mu* weight ?r\gh buoyancy4 ,if1 !n1 ! v]tical dep? ( ! e>?y p>ticles or s& above ! bottom is s small t ! ar*+ effect aga9/ ! sides is negligible1 ! full weight ( ! p>ticles 9 contact1 directly or vic>i\sly1 ) ! bottom acts z pressure on ! bottom1 :ile ! full pressure ( ! wat] acts ?r\gh ! voids or on !m1 or is transmitt$ ?r\gh mat]ial 9 contact ) ! bottom4 ,ref]r+ n[ to mat]ials su* z clays1 peats1 & o!r s(t or pla/ic mat]ials1 x is idle to assume t ^! d n possess pressure-resi/+ & ar*+ prop]ties4 ,= in/ance1 a s(t clay ar* ( l>g] dim5sions1 "u ! condition describ$ e>ly 9 ?is pap]1 w\ld und\bt$ly /& if ! rods support+ ! intrados ( ! ar* 7 key$ back to wa%]s cov]+ a suffici5tly l>ge area4 ,! fact t compress$ air c be us$ at all 9 tunnel "w is evid5ce t semi-aque\s mat]ials h ar*+ prop]ties1 & ! fact t bl[s usually occur 9 light cov] is fur!r evid5ce ( x4 ,:5 air pressure is us$ to hold back ! wat] 9 faces ( l>ge area1 brac+ has to be resort$ to4 ,?is aga9 %[s t :ile full hydro/atic pressure is requir$ to hold back ! wat]1 ! pressure ( ! e>? is 9 a measure indep5d5t ( x4 ,9 a peaty or boggy mat]ial !re is a condition some:at diff]5t1 b suffici5tly alli$ to ! s(t clayey or s\py s&s to place x "u ! same head 9 ord9>y practice4 ,x is und\bt$ly true t piles c be driv5 to an indef9ite dep? 9 ?is mat]ial1 & x is also true t ! action ( ! pile is to displace r ?an compress1 z %[n by ! fact ( driv+ portions ( ! tunnels "u ! ,nor? ,riv] = long di/ances )\t op5+ ! doors ( ! %ield or remov+ any ( ! mat]ial4 ,! case ( fill+ 9 bogs or m>%es1 caus+ !m to s9k at ! po9t ( fill+ & rise else:]e1 is readily expla9$ by ! fact t ! wat] is conf9$ 9 ! int]/ices ( ! mat]ial1 admitt+ ( displacem5t b no compression4 ,! application ( ! above to pressures ov] tunnels 9 mat]ials ( ,class ,a is t ! s& or solid matt] is virtually assum$ to be a s]ies ( columns ) _! bases 9 su* intimate contact ) ! tunnel ro( t wat] _c ex]t pressure on ! tunnel or buoyancy on ! s& at ! po9t ( contact1 & t if ^! columns are suffici5tly deep to h _! upp] portions :olly or p>tly c>ri$ by ! ar*+ or w$g+ action1 ! pressure ( any wat] on _! surfaces is n transf]r$ to ! tunnel1 & ! only aque\s pressure is t :i* acts on ! tunnel betwe5 ! assum$ columns or ?r\gh ! voids4 ,let l ext]ior wid? ( tunnel1 d dep? ( cov]1 z3 ,d,w dep?1 wat] to ro(1 ,d,e e>? to ro(1 ,d,x ( cov] ( e>? necess>y to ar*+ /ability1 t is3 l _/ #ij - phi ,d,x ----- 7 tan4 ------------- phi 7 #b #b _/ l phi ----- tan4 7#de ------- 71 #b #b :]e phi angle ( repose1 & ,d,w ,d,e ,d,x4 ,!n ! pressure on any squ>e foot ( ro(1 z ,v,p z at ! base ( any v]tical ord9ate1 z #i 9 ,fig4 #b1 ,v,o1 ,w,e weight p] cubic foot ( e>? 7#ij lb471 ,w,w wat] 7#fb lb471 we h ,v,p ,v,o ,w,e ,d,w ,w,w #j4dj #a ,v,o #ij ,d,w #fb--- #j4d ,v,o #ij ,d,w #be4 #b ,& = horizontal pressure3 ,ph ! horizontal pressure at any abscissa 7#aj71 ,fig4 #b1 ,a#aj at dep? ( wat] ,d,w#a is ,a#aj #ij #a ,ph --------------- ,d,w#a #fb--- #j4d tan4 phi #b ,a#aj #ij --------------- ,d,w#a #be4 tan4 phi ,! only "q ( s]i\s d\bt is at j :at dep? ! s& is incapable ( ar*+ itself1 b1 = purposes ( safety1 ! writ] has put ?is at ! po9t1 ,f1 z not$ above1 ,d,x1 al?\gh he believes t exp]im5ts on a l>ge scale w\ld %[ x to be ne>] #j4fg;,d,x1 above :i* ! plac+ ( additional back-fill w light5 ! load on ! /ructure4 ,we h1 !n1 = ,d,e ,d,x1 ! weight ( ! total prism ( ! e>? plus ! wat] 9 ! voids1 plus ! add$ pressure ( ! wat] above ! e>? prism1 t is3 ,! pressure p] squ>e foot at ! base ( any v]tical ord9ate ,v,p #a ,v,p ,d,e #ij ,d,e #fb--- #j4dj #b #a 7 ,d,w - ,d,e 7 #fb---4 #b ,to ^? :o may cont5d t wat] act+ ?r\gh s %all[ a prism ( e>? w\ld ex]t full pressure ov] ! full area ( ! tunnel1 x may be /at$ t ! wat] _c ma9ta9 pressure ov] ! :ole area )\t likewise giv+ buoyancy to ! s& previ\sly assum$ to be 9 columns1 9 :i* case !re is ! total weight ( ! wat] plus ! weight ( ! prism ( e>?1 less its buoyancy 9 wat]1 t is #a #a ,v,p ,d,w #fb--- ,d,e 7 #ij - #fb--- 71 #b #b :i*1 by comp>ison ) ! =m] me?od1 w\ld appe> to be less safe 9 its reason+4 ,illu/ration3 ,,comb9$ ,,e>? ,,& ,,wat] ,,pressures4 ,,fig4 #ab4 ,next is ! "q ( pressure aga9/ a wall or brac$ tr5* = mat]ials "u ,class ,a4 ,! pressure ( s& is fir/ calculat$ indep5d5tly1 z %[n 9 ,fig4 #f4 ,r$uc+ ?is to a basis ( #ajj lb4 = ea* division ( ! scale measur$ horizontally1 z %[n1 gives ! l9e1 ,b ,o1 ,fig4 #ab1 measur+ ! outside limit ( pressure due to ! e>?1 ! horizontal di/ance at any po9t betwe5 ?is l9e & ! v]tical face equall+ ! pressure aga9/ t face divid$ by ! tang5t ( ! angle ( repose1 :i* 9 ?is case is assum$ to be #de1 equall+ unity4 ,if ! wat] pressure l9e1 ,c ,f1 is drawn1 x %[s ! relative pressure ( ! wat]4 ,9 ord] to r$uce ?is to ! scale ( #ajj lb4 horizontal measurem5t1 ! l9e1 ,c ,e1 is drawn1 repres5t+ ! wat] pressure to scale1 t is1 s t ea* horizontal measurem5t ( ! scale gives ! pressure on ! face at t po9t2 &1 all[+ #ej = voids1 halv+ ?is area gives ! l9e1 ,c ,d1 betwe5 :i* & ! v]tical face any horizontal l9e measures ! wat] pressure4 ,ext5d+ ^! pressure areas :]e !y ov]lap gives ! l9e1 ,b ,d1 :i* repres5ts ! total pressure aga9/ ! face1 measur$ horizontally4 ,next1 z to ! "q ( buoyancy 9 ,class ,a mat]ials4 ,if a subm]g$ /ructure re/s firmly on a bottom ( m or less firm s&1 its buoyancy1 z indicat$ by ! exp]im5ts1 w only be a p]c5tage ( its buoyancy 9 pure wat]1 correspond+ to ! voids 9 ! s&4 ,9 practice1 h[ev]1 an attempt to %[ ?is condition w fail1 ow+ to ! fact t 9 su* a /ructure ! wat] w almo/ imm$iately "w "u ! edge & bottom1 & cause ! /ructure to rise1 & ! te/ c only be made by measur+ ! diff]5ce 9 uplift 9 a heavi]-?an-wat] /ructure1 z %[n 9 ,exp]im5t ,no4 #e4 ,=1 if a /ructure light] ?an ! displac$ wat] be buri$ 9 s& suffici5tly deep to insure x aga9/ ! influx ( l>ge volumes ( wat] bel[1 x w n rise4 ,t ?is is n due entirely to ! friction ( ! solid mat]ial on ! sides has be5 demon/rat$ by ! obs]vation ( subaque\s /ructures1 :i* always t5d to subside r ?an to lift dur+ or foll[+ di/urbance ( ! surr\nd+ e>?4 ,! foll[+ is quot$ f ! pap] by ,*>les ,m4 ,jacobs1 ,m4 ,am4 ,soc4 ,c4 ,e41 on ! ,nor? ,riv] ,division ( ! ,p5nsylvania ,railroad ,tunnels3,e ,!re 0 consid]able subsid5ce 9 ! tunnels dur+ con/ruction & l9+1 am\nt+ to an av]age ( #j4cd ft4 betwe5 ! bulkhead l9es4 ,?is settlem5t has be5 con/antly decreas+ s9ce con/ruction1 & appe>s to h be5 due almo/ entirely to ! di/urbances ( ! surr\nd+ mat]ials dur+ con/ruction4 ,! silt weighs ab\t #ajj lb4 p] cu4 ft4 99 99 99 & conta9s ab\t #ch ( wat]4 ,x 0 f\nd t :5ev] ?is mat]ial 0 di/urb$ outside ! tunnels a displacem5t ( ! tunnels foll[$4 ,?is 9 sub/ance confirms obs]vations made 9 ! ,batt]y tubes t subsid5ce ( ! /ructure foll[$ di/urbance ( ! outside mat]ial1 al?\gh !oretically ! tubes 7 buoyant 9 ! aque\s mat]ial4 ,! writ] w\ld urge1 h[ev]1 t1 9 all cases ( subm]g$ /ructures only p>tially buri$ 9 solid mat]ial1 excess weight+ be us$ to cov] ! cont+5cies ( vibration1 oscillation1 etc41 to :i* su* /ructures may be subject$ & :i* may ultimately all[ leads ( wat] to "w _! way und]nea?4 ,on ! o!r h&1 he urges t1 9 cases ( floor areas ( deeply subm]g$ /ructures1 su* z tunnels or cell>s1 ! pressure to be resi/$ %\ld be assum$ to be only slightly 9 excess ( t correspond+ to ! pressure due to ! wat] ?r\gh ! voids4 ,! "q ( pressure1 etc41 9 ,class ,b1 or semi-aque\s mat]ials w be consid]$ next4 ,( ^! mat]ials1 z already %[n1 !re are two types3 7a7 s& 9 :i* ! s-call$ quicks& is l>gely 9 excess ( any normal voids1 & 7b7 pla/ic & visc\s mat]ials4 ,! writ] believes t ^! mat]ials %\ld be treat$ z mixtures ( solid & wat]y p>ticles1 9 ! fir/ ( :i* ! quicks&1 or aque\s portion1 be+ virtually 9 susp5sion1 may be treat$ z wat]1 & x mu/ be conclud$ t ! action "h w be simil> to t ( s& & pure wat]1 giv+ a l>g] value to ! prop]ties ( wat] ?an actually exi/s4 ,if1 = in/ance1 x %\ld be f\nd t su* a mixture conta9$ #dj ( pure wat]1 ! writ] w\ld e/imate its pressure on or aga9/ a /ructure z 7a7 t ( a moi/ s& /&+ at a /eep angle ( repose1 & 7b7 t ( cle> wat]1 an all[ance ( #fj ( ! total volume be+ assum$1 & ! sum ( ^! two results giv+ ! total pressure4 ,until m def9ite data c be obta9$ by exp]im5ts on a l>g] scale1 ?is assum$ value ( #fj ( ! total volume = ! aque\s portion may be tak5 = all conditions ( semi-aque\s mat]ials1 except1 ( c\rse1 :]e ! solid & aque\s p>ticles may be cle>ly def9$1 ! pressures be+ comput$ z describ$ 9 ! prec$+ pages4 ,z to ! "q ( pure quicks& 7if su* !re be7 & o!r aque\s mat]ials ( ,class ,c1 su* z wat]1 oil1 m]cury1 etc41 x has already be5 %[n t !y are to be consid]$ z liquids ( _! normal specific gravity2 t is1 9 calculat+ ! air pressure necess>y to displace !m1 "o %\ld consid] _! specific gravity only1 z a factor1 & n ! total weight p] volume includ+ any impurities :i* !y might conta9 undissolv$4 ,9 ord] to h a cle>] conception ( aque\s & semi-aque\s mat]ials & _! action1 !y mu/ be view$ "u conditions n ord9>ily app>5t4 ,= in/ance1 ideas ( s-call$ quicks& are l>gely drawn f see+ /ructures s9k+ into x1 or f obs]v+ x fl[+ ?r\gh voids 9 ! %eet+ or cas+4 ,! action ( s& & wat] "u pressure is view$ dur+ or aft] a slump1 :5 ! damage is be+ done1 or has be5 done1 :]eas ! correct view-po9t is "u /atic conditions1 be=e ! slump takes place4 ,! foll[+ is quot$ f ! report ( ,mr4 ,c4,m4 ,jacobs1 ,*ief ,eng9e] ( ! ,ea/ ,riv] ,gas ,tunnel1 built 9 #ahib-ic3 ,we f\nd t ! mat]ial :i* _h h]et(ore be5 firm or /iff _h1 "u erosion1 obta9$ a s\p-l consi/5cy1 & t a huge cavity "s #c ft4 wide & #bf ft4 deep _h be5 wa%$ up t[>d ! riv] b$4 ,?is w\ld probably be a fair description ( mu* ( ! mat]ial ( ?is class met ) 9 su* "w1 if compress$ air _h n be5 us$4 ,! writ] believes t 9 s(t mat]ial surr\nd+ subm]g$ /ructures ! wat] actually conta9$ 9 ! voids is n infrequ5tly1 aft] a prolong$ p]iod ( re/1 cut (f absolutely f its s\rces ( pressure & t contact ) ^! s\rces ( pressure w n aga9 be resum$ until a leak takes place ?r\gh ! /ructure2 &1 ev5 :5 !re is a small fl[ or trickl+ ( wat] ?r\gh su* mat]ial1 x conf9es itself to c]ta9 pa?s or *annels1 & is l>gely exclud$ f ! g5]al mass4 ,! broad pr9ciple ( ! be>+ p[] ( soil has be5 made ! subject ( too _m exp]im5ts & too mu* controv]sy to be consid]$ 9 a pap] :i* is int5d$ to be a description ( exp]im5ts & obs]v$ data & notes !refrom4 ,! writ] is ( ! op9ion1 h[ev]1 t entirely too little att5tion has be5 giv5 to ?is be>+ p[] ( ! soil2 t :ile progress has be5 made 9 our k ( all classes ( mat]ials = /ructures1 v little has be5 done :i* leads to any real k ( ! mat]ial on :i* ! f\ndation re/s4 ,= in/ance1 x is inconceivable t #a or #b tons may sometimes be all[$ on a squ>e foot ( s(t clay1 :ile ! load on firm gravel is limit$ to f #d to #f tons4 ,! writ]'s practical obs]vations h conv9c$ him t x is frequ5tly mu* saf] to put f\r times #f tons on a squ>e foot ( gravel ?an x is to put "o-f\r? ( #b tons on a squ>e foot ( s(t clay4 ,9 connection ) ! be>+ p[] ( soil1 ! writ] also believes t too little /udy has be5 giv5 to ! que/ions ( ! lat]al pressure ( e>?1 & he desires to quote "h f "s exp]im5ts describ$ 9 a book,f publi%$ 9 ,engl& 9 #ahgf1 to :i* 8 att5tion has rec5tly be5 call$4 ,?is book appe>s to h be5 int5d$ = "y p1 b x is ( int]e/ to note ! foll[+ quotations f a *apt] entitl$ ,s&4 ,?is *apt] beg9s by /at+ t3 ,dur+ ! c\rse ( a lecture on ! ,suez ,canal by ,mr4 ,john ,h4 ,pepp]1 :i* 0 deliv]$ nightly by him at ! ,polyte*nic ,in/itute 9 ,london1 he illu/rat$ 8 lecture by "s exp]im5ts design$ to exhibit c]ta9 prop]ties ( s&1 :i* _h ref]5ce to ! con/ruction ( ! ,suez ,canal1 & x is /at$ t ?\gh ! prop]ties 9 "q 7 by no means to be class$ among rec5t discov]ies1 ! exp]im5ts 7 novel 9 =m & s]v$ to int]e/ ! public audi5ce4 ,fur!r quotation foll[s3 ,:5 ! ,suez ,canal 0 project$1 _m prophesi$ evil to ! und]tak+1 f ! s& 9 ! des]t be+ drift$ by ! w9d into ! canal1 & o!rs 7 appreh5sive t :]e ! canal 0 cut ?r\gh ! s& ! bottom w\ld be pu%$ up by ! pressure on ! banks 99 99 994 ,! pr9ciple ( lat]al pressure may n[ be /rik+ly illu/rat$ by tak+ an ,am]ican wood5 pail &1 hav+ previ\sly cut a l>ge circul> hole 9 ! bottom1 ?is is n[ cov]$ ) f9e tissue pap]1 :i* %\ld be c>efully pa/$ on to prev5t ! p>ticles ( s& f fl[+ ?r\gh ! small op5+s betwe5 ! pap] & ! wood 99 99 99 & be+ plac$ upright & rapidly fill$ ) s&1 x may be c>ri$ ab\t by ! h&le )\t ! slighte/ fe> ( ! weight ( ! s& break+ ?r\gh ! ?9 m$ium4 99 99 99 ,probably "o ( ! mo/ conv9c+ exp]im5ts is t :i* may be p]=m$ ) a cyl9drical tube #ah 94 long & #b 94 9 diamet]1 op5 at bo? ends4 ,a piece ( tissue pap] is c>efully pa/$ on "o end1 s t :5 dry no cracks or int]/ices are left4 ,! tube is fill$ ) dry s& to a height ( say #ab 94 ,9 ! upp] "p is ins]t$ a solid plug ( wood #ab 94 long & ( ! same or v ne>ly ! same diamet] z ! inside ( ! tube1 s t x w move freely up & d[n l ! pi/on ( an air pump4 ,! tube1 s&1 & pi/on be+ arrang$ z describ$1 may n[ be held by an assi/ant & ! demon/rator1 tak+ a sl$ge hamm]1 may proce$ to /rike /eadily on ! end ( ! pi/on &1 al?\gh ! pap] w bulge out a little1 ! =ce ( ! bl[ w n break x4 ,if ! assi/ant hold+ ! tube all[s x to j]k or reb\nd aft] ea* bl[ ( ! hamm]1 ! pap] may break1 because air & s& are driv5 d[n by ! succe$+ bl[1 & !re=e x mu/ be held /eadily s t ! pi/on be>s fairly on ! s& ea* "t4 ,a /ill m conclusive & /rik+ exp]im5t may be %[n ) a framework ( metal con/ruct$ to repres5t a pail1 ! sides ( :i* are clos$ up by pa/+ %eets ( tissue pap] inside & ov] ! l[] "p4 ,z be=e demon/rat$1 :5 a quantity ( s& is p\r$ into ! pail ! tissue pap] cas+ at ! bottom does n break1 b if a suffici5t quantity is us$ ! sides =m$ ( tissue pap] bulge out & usually give way 9 consequ5ce ( ! lat]al pressure ex]t$ by ! p>ticles ( s&4 ,! writ] has made ! second exp]im5t not$1 ) special app>atus1 & f9ds t ) tissue pap] ov] ! bottom ( a #b-;94 pipe1 #ae 94 long1 ab\t #ab 94 ( s& w /& ! bl[ ( a heavy sl$ge hamm]1 transmitt$ ?r\gh a wood5 pi/on1 at lea/ once & sometimes two or ?ree times1 :ile heavy bl[s giv5 ) a light] hamm] h no effect at all4 ,t ?is is n due 9 any l>ge measure to in]tia c be %[n by ! fact t m ?an #bjj lb4 c safely be put on top ( ! wood5 pi/on4 ,x _c be acc\nt$ = entirely by ! friction1 z ! removal ( ! pap] all[s ! s& to drop 9 a mass4 ,! explanation is t ! pressure is transmitt$ lat]ally to ! sides1 & z ! friction is directly proportional to ! pressure1 ! load or effect ( ! bl[ is c>ri$ by ! proportional increase 9 ! friction1 & any diaphragm :i* w c>ry ! direct bottom load w n h its /resses l>gely increas$ by any great] load+ on top4 ,! writ] believes t exp]im5ts w %[ t 9 a s&-jack ! t5d5cy w be = ! sides to bur/ r ?an ! bottom1 & t ! outfl[ f an orifice at or ne> ! bottom is n ei!r greatly ret>d$ or accel]at$ by ord9>y pressure on top4 ,! occurr5ce ( abnormal voids1 h[ev]1 causes ! s& to be displac$ into !m4 ,! important consid]ation ( ?is pap] is t all ! exp]im5ts & obs]vations not$ po9t conclusively to ! fact t pressure is transmitt$ lat]ally ?r\gh gr\nd1 mo/ probably along or ne>ly p>allel to ! angles ( repose1 or 9 cases ( rock or /iff mat]ial1 along a l9e :i*1 until m conclusive exp]im5ts are made1 may be tak5 z a mean betwe5 ! horizontal & v]tical1 or approximately #de degrees4 ,!re is no reason to believe t ?is is n ! case ?r\gh\t ! entire mass ( ! e>?1 t ea* cubic foot1 or y>d1 or mile is support$ or 9 turn supports its neighbor+ equival5t along su* l9es4 ,! !ory is n a new "o1 & its field is too l>ge to encompass )9 ! limits ( a s+le pap]1 b1 = practical purposes1 & )9 ! limit$ areas to :i* we mu/ necess>ily be conf9$1 ! writ] believes x c be e/abli%$ beyond controv]sy z true4 ,c]ta9 x is t no "o has yet f\nd1 9 gr\nd free f wat] pressure or abnormal conditions1 any evid5ce ( great] pressure at ! bottom ( a deep %aft or tunnel ?an t ne> ! surface4 ,pressures due to ! wid5+ ( m9es beyond ! limits ( safety mu/ n be tak5 z a controv]sion ( ?is /atem5t1 z all ar*es h limits ( safety1 m especially if ! useless mat]ial bel[ ! !oretical intrados is only p>tly support$1 or is all[$ to be susp5d$ f ! natural ar*4 ,! writ] believes1 also1 t ! "q ( conf9$ f\ndations1 9 contradi/9ction to t ( ! spread+ ( f\ndations1 may be wor?y ( full discussion1 z x applies to safe & economical con/ruction1 & he (f]s1 )\t special comm5t1 ! foll[+ obs]vations3 ,he has f\nd t1 9 s(t gr\nd1 results are (t5 obta9$ ) small op5 caissons sunk to a dep? ( a few feet & clean$ out & fill$ ) concrete1 :i* (f] mu* bett] resi/ance ?an spread+ ! f\ndation ov] f\r or five times ! equival5t area4 ,he has f\nd t small /eel piles & c(f]-dams1 f #a-;ft4 cyl9d]s to c(f]-dams #d or #e ft4 squ>e1 sunk to a dep? ( only #a or #b ft4 bel[ adjac5t excavations 9 ord9>y s&1 h safely resi/$ loads f\r or five times z great z ^? usually all[$4 ,he believes t %ort cyl9d]s1 clean$ out & fill$ ) concrete1 or c(f]-dams ( %ort /eel pil+ ) ! surface clean$ out to a reasonable dep? & fill$ ) concrete horizontally re9=c$1 w1 9 _m in/ances1 give z good results z1 &1 9 mo/ cases1 v mu* bett] ?an1 plac+ ! f\ndation on an equival5t numb] ( small long piles or a proportionately great] spread ( f\ndation area1 ! idea be+ t ! transmission ( pressure to ! sides ( ! c(f]-dam w n only conf9e ! side ?ru/1 b w also transf] ! load+ 9 mass to a great] dep? :]e ! resi/ance to lat]al pressure 9 ! gr\nd w be m /able2 t is1 ! great] dep? ( f\ndation is ga9$ )\t ! increas$ excessive load+1 or necessity = deep excavation4 ,z to ! "q ( ! be>+ value & friction on piles1 ! writ] believes t :ile ! lit]ature on eng9e]+ is full ( exp]im5tal data relat+ to friction on caissons1 !re is little to %[ ! real value ( friction on piles4 ,! assumption g5]ally made ( an assum$ be>+ value1 & ! d$uction !refrom ( a value = ! sk9 friction is fallaci\s4 ,di/9ction1 also1 is n made1 b %\ld be cle>ly drawn betwe5 sk9 friction1 pure & simple1 on smoo? surfaces1 & ! friction due to pressure4 ,too (t5 ! be>+ value on irregul> surfaces z well z ! be>+ due to tap] 9 piles1 & la/ly ! resi/ance (f]$ by b9d+1 ent] into ! det]m9ation ( s-call$ sk9 friction =mulas4 ,! ess5tial condition ( s9k+ a caisson is keep+ x plumb2 & b9d+1 :i* is ano!r way ( writ+ increas$ be>+ value1 w (t5times be fatal to success4 ,! writ] believes t a s]ies ( obs]vations on caissons sunk plumb "u homog5e\s conditions ( gr\nd & sup]ficial smoo?ness w %[ a proportional increase ( sk9 friction p] squ>e foot av]age = ea* increase 9 ! size ( caissons1 z well z = increase ( dep? 9 ! s9k+ up to c]ta9 po9ts1 :]e x may f9ally become con/ant1 z w be %[n lat]4 ,! det]m9ation ( ! actual friction or coeffici5t ( friction betwe5 ! surfaces ( ! pile & ! mat]ial x enc\nt]s1 is n difficult to det]m9e4 ,9 s& x is approximately #dj ( ! pressure = reasonably smoo? iron or /eel1 & #de ( ! pressure = ord9>y wood surfaces4 ,if1 = in/ance1 a long %aft be )drawn v]tically f m\ld+ s&1 ! hole may rema9 indef9itely z long z wat] does n get into x or x does n dry out4 ,?is is due to ! t5d5cy ( ! s& to ar* itself horizontally ov] small areas4 ,! same op]ation _c be p]=m$ on dry s&1 z ! ar*+ prop]ties1 :ile protect+ ! pile f excessive pressure due to excessive l5g?1 w n prev5t ! loose s& imm$iately surr\nd+ ! pile f ex]t+ a con/ant pressure aga9/ ! pile1 & x is ( ?is pressure t #de may be tak5 z ! real value ( sk9 friction on piles 9 dry s&4 ,9 s(t clays or peats :i* are displac$ by driv+1 ! t5d5cy ( ?is mat]ial to fl[ back into ! orig9al space causes pressure1 ( :i* ! friction w be a measur$ p]c5tage4 ,9 ?is case1 h[ev]1 ! friction itself betwe5 ! mat]ial & ! clays or peat is usually v mu* less ?an #dj1 & x is = ?is reason t piles ( almo/ indef9ite l5g? may be driv5 9 mat]ials ( ?is "* )\t (f]+ suffici5t resi/ance to be dep5d$ on1 z long z no good be>+ gr\nd is f\nd at ! po9t4 ,if ?is mat]ial is "u wat]1 & is s s(t z to be consid]$ semi-aque\s1 ! pressure p] squ>e foot w increase 9 dim9i%+ proportion to ! dep?1 & ! pressure p] area w soon approa* & become a con/ant1 due to ! resi/ance (f]$ by ! lat]al ar*+ ( ! solid mat]ial2 :]eas1 9 l>ge circul> caissons1 or caisson %afts1 :]e ! horizontal ar*+ effect is virtually de/roy$1 or at lea/ r5d]$ non-effective until a great dep? is rea*$1 ! pressure mu/ necess>ily v>y "u ^! conditions proportionately to ! dep? & size ( ! caisson 9 semi-aque\s mat]ial4 ,on ! o!r h&1 9 l>ge caisson %afts1 especially ^? :i* are squ>e1 ! pressure at ! top due to ! solid mat]ial w also increase proportionately to ! dep?1 z already expla9$ 9 connection ) ! pressures ( e>? aga9/ %eet+ & reta9+ walls4 ,! writ] believes t ! pressure on ^! surfaces may be det]m9$ ) reasonable accuracy by ! =mulas already giv5 9 ?is pap]1 & ) ^! pressures1 multipli$ by ! coeffici5t ( friction det]m9$ by ! simple/ exp]im5t on ! gr\nd1 results may be obta9$ :i* w closely approximate ! actual friction on caissons at giv5 dep?s4 ,! friction on caissons1 :i* is usually giv5 at f #bjj to #fjj lb4 p] sq4 ft41 is frequ5tly assum$ to be ! same on piles #ab 94 or less 9 diamet]1 :]eas ! pressures on ^! surfaces1 z %[n1 are 9 no way comp>able4 ,! foll[+ notes & obs]vations are giv5 9 connection ) ! sk9 friction & ! be>+ value ( piles3 ,! writ] has 9 8 possession a copy ( an (ficial pr9t :i* 0 rec5tly furni%$ to bidd]s 9 connection ) ! f\ndation = a l>ge public build+ 9 ,new ,york ,city4 ,! exp]im5ts 7 made on good s& at a dep? ( approximately #dc ft4 bel[ wat] & #dg ft4 bel[ an adjac5t excavation4 ,9 ?is in/ance a #af-;94 pipe 0 sunk to ! dep? /at$1 clean$ out1 & a #ad-;94 pi/on connect$ to a #aj-;94 pipe 0 ins]t$ & ! gr\nd at ! bottom ( ! #af-;94 pipe subject$ to a load+ approximat+ #bh tons p] sq4 ft4 ,aft] an initial settlem5t ( ne>ly #c 941 !re 0 no fur!r settlem5t ov] an ext5d$ p]iod1 al?\gh ! load ( #bh tons p] sq4 ft4 0 cont9u$4 ,9 connection ) "s rec5t und]p9n+ "w1 #ad-;94 holl[ cyl9drical piles #f ft4 long 7 sunk to a dep? ( #f ft4 ) an ord9>y h&-hamm]1 be+ excavat$ z driv54 ,^! piles 7 !n fill$ ) concrete & subject$ to a load+ 9 "s cases approximat+ #fj tons4 ,aft] a settlem5t rang+ f #i to #ac 941 no fur!r settlem5t took place1 al?\gh ! load+ 0 ma9ta9$ = a consid]able p]iod4 ,9 connection ) "s o!r pile "w1 ! writ] has se5 a #aj-;94 pipe1 #c_/h 94 ?ick1 #d ft4 bel[ ! bottom ( an op5 cyl9d]1 at a dep? ( ab\t #bj ft41 su/a9 9 gravel & s& a load approximat+ #ej tons :5 clean$ out to )9 #b ft4 ( ! bottom4 ,he has se5 o!r cyl9drical piles ) a be>+ r+ ( n m ?an 94 re/+ on gravel at a dep? ( f #bj to #cj ft41 clean$ out practically to ! bottom1 su/a9 a measur$ load ( #fj tons )\t settlem5t4 ,z to sk9 friction 9 s&1 a case came "u 8 obs]vation :]e9 a #ad-;94 holl[ cyl9drical pile :i* _h /ood = #bh days at a dep? ( ab\t #cj ft4 9 ! s&1 0 clean$ out to its bottom & subject$ to hydraulic pressure1 measur$ by a gauge1 & sunk #b ft4 into ! s& )\t any pressure be+ regi/]$ on ! gauge4 ,x %\ld be expla9$1 h[ev]1 t ! gauge c\ld be subject$ to a pressure ( #bej lb41 equal to a total pressure ( #g1jjj lb4 on ! pi/on ( ! jack )\t regi/]+1 :i* correspond$1 assum+ x all z sk9 friction1 to a maximum ( n m ?an #gh lb4 p] sq4 ft41 b x %\ld be not$ t ?is includ$ be>+ value z well1 & t ! pressure 0 v f> f #g1jjj lb41 9 all probability1 at ! beg9n+ ( ! te/4 ,9 ! case ( ! ,cali=nia /ove-pipe wells driv5 by ! ,bo>d ( ,wat] ,supply on ,long ,isl&1 ! writ] is in=m$ t "o ( ^! tubes1 #ab 94 9 diamet]1 0 sunk to a dep? ( #hej ft4 ,9 do+ ?is "w ! pile 0 excavat$ bel[ ! foot+ ) a s& pump & 0 !n sunk by hydraulic pressure4 ,assum+ ! maximum capacity ( ! jacks at #ajj tons1 :i* is n probable1 ! sk9 friction c\ld n h am\nt$ to m ?an #ge lb4 p] sq4 ft4 ,x _c be assum$ 9 ?is case t ! excavation ( ! mat]ial bel[ ! pile reliev$ ! sk9 itself ( "s ( its friction1 z ! op]ation consum$ m ?an #f weeks1 &1 ev5 if excess mat]ial 0 remov$1 x is c]ta9 t a l>ge p]c5tage ( x w\ld h _h "t to adju/ itself be=e ! op]ation 0 complet$4 ,illu/ration3 ,,plate ,,xxix1 ,,fig4 #a4--;,a #ad-;,,gauge1 #ad-;,,941 ,,holl[ 7,,non-,,telescopic71 ,,cali=nia ,,/ove-,,pipe ,,pile ,,:i* ,,met ,,imp5etrable ,,mat]ial4 ,illu/ration3 ,,plate ,,xxix1 ,,fig4 #b4--;,,*5[e? ,,pile1 ,,p5etrat+ ,,h>d ,,mat]ial4 ,9 connection ) ?is1 ! writ] may call att5tion to ! fact t piles driv5 9 silt along ! ,nor? ,riv]1 & 9 s(t mat]ial at o!r places1 are sometimes #ij ft4 9 l5g?1 & ev5 !n d n (f] suffici5t resi/ance to be dep5d$ on = load+4 ,?is is due to ! fact t ! end ( ! pile does n be> 9 good mat]ial4 ,! relation betwe5 be>+ value & sk9 friction on a pile1 :]e ! end be>+ is 9 good mat]ial1 is well %[n by a case :]e a wood5 pile,g /ruck solid mat]ial1 0 di/ort$ "u ! cont9ual bl[s ( ! hamm]1 & 0 aft]w>d expos$4 ,x is also %[n 9 ! case ( a #ad-;94 ,cali=nia /ove-pipe pile1 ,no4 #ad gauge1 ! po9t ( :i* met firm mat]ial4 ,! result1 z %[n by ,fig4 #a1 ,plate ,,xxix1 speaks = itself4 ,fig4 #b1 ,plate ,,xxix1 %[s a ,*5[e? pile :i* 0 an exp]im5tal "o driv5 by its design]4 ,?is pile1 aft] gett+ into h>d mat]ial1 0 subject$ to ! bl[ ( a #d1jjj-lb4 hamm] fall+ ! full l5g? ( ! pile-driv]1 & ! only result 0 to %att] ! head ( ! pile1 & n cause fur!r p5etration4 ,mr4 ,*5[e? has /at$ to ! writ] t he has f\nd mat]ial s compact t x c\ld n be p5etrat$ ) a solid pile--ei!r ) or )\t jett+--:i* is 9 l9e ) ! writ]'s exp]i5ce4 ,! writ] believes t ! =ego+ notes w %[ conclusively t ! factor to be s\ght 9 pile "w is be>+ value r ?an dep? or sk9 friction1 &1 h[ev] valuable sk9 friction may be 9 ! l>g] caissons1 x _c be dep5d$ on 9 ! case ( small piles1 except 9 values rang+ f #be to #ajj lb4 p] sq4 ft4 ,9 conclusion1 he desires to ?ank ! foll[+ g5tlem51 :o h contribut$ to ! success ( ! exp]im5ts not$ h]e93 ,mr4 ,james ,w4 ,nelson1 ( ,ri*>d ,dudgeon1 ,new ,york2 ,mr4 ,george ,noble1 ( ,john ,simmons & ,company1 ,new ,york2 & ,mr4 ,p5dleton1 ( ,h9dley & ,p5dleton1 ,brooklyn1 ,n4,y42 all ( :om h furni%$ app>atus = ! exp]im5ts & h tak5 an int]e/ 9 ! results4 ,& la/ly1 he desires especially to ?ank ,mr4 ,f4,l4 ,cran=d1 ( ! ,cran=d ,company1 = m5 & mat]ial ) :i* to make ! exp]im5ts & )\t ^: co-op]ation x w\ld h be5 impracticable = ! writ] to h made !m4 ,?r\gh\t ?is pap] ! writ] has endeavor$1 z f> z possible1 to d$uce f 8 obs]vations & f ! obs]vations ( o!rs1 z f> z he has be5 able to obta9 !m1 practical data & =mulas :i* may be ( use 9 e/abli%+ ! relation%ip betwe5 ! pressure1 resi/ance1 & /ability ( e>?s2 &1 :ile he does n wi% to dictate ! "* ( ! discussion1 he does ask t ^? :o h made obs]vations ( a simil> "* or :o h available data1 w1 z f> z possible1 contribute ! same to ?is discussion4 ,x is only by su* obs]vations & exp]im5ts1 & d$uctions !refrom1 t eng9e]s may obta9 a bett] k ( ! h&l+ ( su* mat]ials4 ,! writ] believes t too mu* has be5 tak5 = grant$ 9 connection ) e>? pressures & resi/ance2 & t1 f> too (t51 obs]vations ( ! results ( natural laws h be5 set d[n z ph5om5a4 ,he believes t1 bo? 9 exp]im5t+ & obs]v+1 ! eng9e] w frequ5tly f9d :at is be+ look$ = or expect$ & w fail to see ! obvi\s alt]native4 ,he may add t 8 own exp]im5ts & obs]vations may be criticiz$ = ! same reason1 & he asks1 !re=e1 t all possible light be ?r[n on ?is subject4 ,a comp>ative /udy ( mu* ( our exp]t te/imony or ( ! plans ( almo/ any ( ! /ructures design$ 9 connection ) _! be>+ ^u e>?1 or resi/ance to e>? pressure1 w %[ t "u ! pres5t me?ods ( int]pretation ( ! und]ly+ pr9ciples gov]n+ ! calculations & designs relat+ to su* /ructures1 ! results v>y f> too widely4 ,too mu* is left to ! judgm5t ( ! eng9e]1 & too frequ5tly no fix$ /&>ds c be f\nd = "s ( ! mo/ ess5tial conditions4 ,until ! eng9e] c say ) c]ta9ty t 8 calculations are reasonably bas$ on facts1 he is =c$ to admit t 8 design mu/ be lack+1 ei!r 9 ! elem5ts ( safety1 on ! "o h&1 or ( economy1 on ! o!r1 &1 until he c give to 8 cli5t a full measure ( bo? ^! factors 9 fair proportion1 he _c ju/ly claim t 8 pr(ession has rea*$ its full developm5t4 ,table #a gives approximate calculations ( pressures on two types ( tunnels & on two heights ( %eet$ faces or walls1 due to f\r v>y+ classes ( mat]ials4 ,,table #a4--,,pressures ,,on ,,typical ,,/ructures ,,"u ,,v>y+ ,,assum$ ,,conditions4 ,illu/ration3 ,key to ,table ( ,pressures1 etc4 h ext]ior height1 l ext]ior wid?1 delta dep? ( cov]1 t is1 ,d,e e>?1 & ,d,w wat] dep?1 phi angle ( repose1 &1 = tunnels ,d,w ,d,e a dep? l phi ----- 7 #de ------- 7 #b #b ,w,e weight ( #a cu4 ft4 ( e>? #ij lb42 ,w,w weight ( #a cu4 ft4 ( wat] #fb lb4 ,conditions3 #a normal s&1 #b dry s&1 #c sup]saturat$ firm s& ) #dj ( voids1 #d sup]saturat$ semi-aque\s mat]ial1 #fj aque\s1 t is1 #fj wat] & aque\s mat]ial4 ,comb9$ assum$ h l phi ,d,e conditions4 ,i#a #bj #cj #de #dj ,i#b #bj #cj #cj #dj ,,ii#a #ae #ae #de #dj ,,ii#b #ae #ae #cj #dj ,,iii#a #ae #de #ae ,,iii#b #ae #cj #ae ,,iv#a #cj #de #cj ,,iv#b #cj #cj #cj ,comb9$ assum$ h l phi ,d,e ,d,w conditions4 ,i#c #bj #cj #ej #dj #fj ,i#d #bj #cj #dj #dj #fj ,,ii#c #ae #ae #ej #dj #fj ,,ii#d #ae #ae #dj #dj #fj ,,iii#c #ae #ej #ae #ae ,,iii#d #ae #dj #ae #ae ,,iv#c #cj #ej #cj #cj ,,iv#d #cj #dj #cj #cj ,,approximate ,,pressures ,,on ,,tunnels1 ,,p] ,,squ>e ,,foot4 ,pressure ,i#a ,i#c ,i#c ,i#c ,i#b ,i#d ,i#d ,i#d p] squ>e,e>?4,e>?4,wat]4,comb9$4,e>?4,e>?4, wat]4,comb9$4 foot1 at ,a #c1bdj #c1fij #a1ejj #e1aij #b1cbe #b1hhj #b1bej #e1acj ,b #b1gde #c1aje #a1ejj #d1fje #a1hde #b1che #b1bej #d1fce ,c #b1afj #b1dge #a1ejj #c1ige #a1cej #a1hjj #b1bej #d1jej ,d #dej #edj #a1ejj #b1jdj #dej #dej #b1bej #b1gjj ,e #cfj #cfj #a1fbe #a1ihe #dej #dej #b1dch #b1hhh ,f #bgj #bgj #a1gej #b1jbe #dej #cfj #b1fbf #b1ihf ,g #bbe #bbe #a1hge #b1ajj #cfj #bgj #b1had #c1jhd ,pressure ,,ii#a;,,ii#c;,,ii#c;,,ii#c ,,ii#b;,,ii#d;,,ii#d;,,ii#d p] squ>e,e>?4,e>?4,wat]4,comb9$4,e>?4,e>?4, wat]4,comb9$4 foot at ,a #a1dhe #a1gee #a1ejj #c1bee #a1jce #a1cje #b1bej #c1eee ,b #a1cje #a1dhe #a1ejj #b1ihe #ide #a1agj #b1bej #c1dbj ,c #a1abe #a1bae #a1ejj #b1gae #haj #iij #b1bej #c1bdj ,d #dje #dje #a1ejj #a1ije #edj #dej #b1bej #b1gjj ,e #dje #dje #a1fbe #b1jcj #edj #dej #b1dch #b1hhh ,f #cfj #cfj #a1gej #b1aaj #edj #dej #b1fbf #c1jgf ,g #cae #cae #a1hge #b1aij #cfj #cfj #b1had #c1agd ,h #ahj #bbe #b1jjj #b1bbe #ahj #ahj #c1jjj #c1ahj ,i #ij #aaj #b1age #b1bhe #ace #ace #c1ahh #c1cbc ,,approximate ,,pressures ,,on ,,%eet$ ,,tr5* ,,faces ,,or ,,walls ,pressure ,,iii#a;,,iii#c;,,iii#c;,,iii#c;,,iii#b; ,,iii#d;,,iii#d;,,iii#d p] squ>e,e>?4 ,e>?4 ,wat]4 ,total ,e>?4 ,e>?4 ,wat]4 ,total foot at e>? e>? & & wat]4 wat]4 ,a #ege #eaj #ajj #faj #a1cej #haj #adj #iej ,b #djj #cej #aij #edj #ijj #edj #bfj #hjj ,c #bjj #age #bhj #dee #dej #bgj #chj #fej ,pressure ,,iv#a;,,iv#c;,,iv#c;,,iv#c;,,iv#b;,,iv# d;,,iv#d;,,iv#d p] squ>e,e>?4,e>?4,wat]4,total ,e>?4,e>?4,wat]4,total foot at e>? e>? & & wat]4 wat]4 ,a #a1cgj #a1baj #ajj #a1caj #c1age #a1iaj #aej #b1jfj ,b #a1agj #a1jcj #bjj #a1bcj #b1gjj #a1faj #bij #a1ijj ,c #igj #hee #bij #a1ade #b1bej #a1cee #dcj #a1ghe ,d #gge #fhj #cgj #a1jej #a1hjj #a1ajj #egj #a1fgj ,e #eij #eae #dfj #ige #a1cej #hbj #gaj #a1ecj ,f #djj #cej #efj #iaj #ijj #edj #hfj #a1djj ,g #aij #agj #fej #hbj #dej #bge #a1jjj #a1bge ,,footnotes3 ,footnote ,a3 ,pres5t$ at ! meet+ ( ,may #ah?1 #aiaj4 ,footnote ,b3 ,transactions1 ,am4 ,soc4 ,c4 ,e41 ,vol4 ,,lx1 p4 #a4 ,footnote ,c3 ,eng9e]+ ,news1 ,july #a/1 #aiji4 ,footnote ,d3 ,f ,gravel = ,good ,roads4 ,footnote ,e3 ,transactions1 ,am4 ,soc4 ,c4 ,e41 ,vol4 ,,lxviii1 pp4 #eh-fj4 ,footnote ,f3 ,discov]ies & ,inv5tions ( ! ,n9ete5? ,c5tury1 by ,rob]t ,r\tl$ge1 ,assi/ant ,exam9] 9 ,*emi/ry & 9 ,natural ,philosophy to ! ,univ]sity ( ,london4 ,footnote ,g3 ,eng9e]+ ,news1 ,janu>y #ae?1 #aiji4 ,,discussion ,t4 ,,k5n>d ,,?omson1 ,m4 ,,am4 ,,soc4 ,c4 ,e4--,al?\gh ! au?or des]ves great cr$it = ! c>eful & ?or\gh mann] 9 :i* he has h&l$ ?is subject1 8 pap] %\ld be label$ ,dang]\s = ,beg9n]s1 especially z he is an eng9e] ( great practical exp]i5ce2 if he 7 n1 comp>atively little att5tion w\ld be paid to 8 /atem5ts4 ,! pap] is dang]\s because _m w read only portions ( x1 or w n read x ?or\ghly4 ,= in/ance1 at ! beg9n+1 ! au?or cites sev]al exp]im5ts 9 :i* consid]able =ce is requir$ to />t ! lift+ ( a weight or plung] 9 s& & wat] & mu* less aft] ! />t4 ,?is rem9ds ! speak] ( ! "t :51 z a s*oolboy1 he tri$ to pick up /ones f ! bottom ( ! riv] & 0 told t ! suction 0 caus$ by atmosph]ic pressure4 ,! inf]5ce is t tunnels1 etc41 9 s&1 etc41 are n 9 any dang] ( ris+1 ev5 ?\gh !y are light] ?an wat]4 ,t[>d ! end ( ! pap]1 h[ev]1 ! au?or /ates t tunnels %\ld be weight$1 b he r spoils ?is by /at+ t !y %\ld be weight$ only en\gh to ov]come ! actual wat] pressure1 t is1 betwe5 ! voids ( ! s&4 ,x seems to ! speak] t ! only really safe way is to make ! tunnel at lea/ z heavy z ! wat] displac$ 9 ord] to prev5t x f com+ up1 & to take o!r measures to prev5t x f go+ d[n4 ,! ,city ( ,toronto1 ,canada1 =m]ly pump$ its wat] supply ?r\gh a #f-;ft4 iron pipe1 buri$ 9 ! s& "u ,toronto ,bay & !n "u ,toronto ,isl&1 ) an intake 9 ! deep wat] ( ! lake4 ,dur+ a /orm a mass ( seawe$1 etc41 0 wa%$ aga9/ ! intake1 completely block+ x1 & al?\gh ! man at ! pump+ /ation knew t some?+ 0 wrong1 he cont9u$ to pump until ! wat] 0 drawn out ( ! pipe1 ) ! result t ab\t half a mile ( ! conduit />t$ to rise & !n broke at sev]al places1 ?us all[+ x to fill ) wat]4 ,ev5tually1 ! city w5t d[n to b$-rock "u ! ,bay = its wat] tunnel4 ,ano!r reason = call+ ?is pap] dang]\s = beg9n]s is t x is improbable t exp]i5c$ eng9e]s or contractors w omit ! brac+ at ! bottom1 al?\gh1 s9ce ! pap] 0 pr9t$1 a gl>+ in/ance has occurr$ :]e comp>atively little brac+ 0 put 9 ! bottom ( a #dj-;ft4 cut1 ! result be+ a bad cave-9 f ! bottom1 al?\gh all ! top braces rema9$ 9 place4 ,mo/ eng9e]s w agree t ne>ly e crib :i* has fail$ slipp$ out f ! bottom1 & did n turn ov]4 ,! objection to ! angle ( repose is t x is n possible to asc]ta9 x = any mat]ial deposit$ by ,nature4 ,x c\ld probably be asc]ta9$ = a s& bank deposit$ by ,man1 b n = an excavation to be made 9 ! gr\nd1 = x is kn[n t ne>ly all e>?1 etc41 has be5 deposit$ "u great pressure1 & is likely to be cem5t$ toge!r by clay1 loam1 roots1 trees1 b\ld]s1 etc41 & diff]s 9 "* e few feet4 ,a deep v]tical cut c (t5 be made1 ev5 9 ,new ,york quicks&1 f :i* ! wat] has be5 drawn1 &1 if n subject$ to j>s1 wat]1 etc41 ?is mat]ial w /& = consid]able "t & !n come d[n l an avalan*e1 kill+ any "o 9 its way4 ,9 su* cases v little brac+ w\ld prev5t ! slide f />t+1 provid$ ra91 etc41 did n loos5 ! mat]ial4 ,! au?or1 ( c\rse1 treats dry & wet mat]ials diff]5tly1 b !re are v few places :]e dry mat]ial is n likely to become wet be=e ! excavation is complet$4 ,9 caisson "w1 if ! caisson c be kept absolutely plumb1 x c be sunk )\t hav+ to ov]come mu* friction1 :ile1 on ! o!r h&1 if x is n kept plumb1 ! mat]ial is m or less di/urb$ & beg9s to b9d1 caus+ consid]able friction4 ,! au?or claims t ! pressure does n increase ) ! dep?1 b all caisson m5 w probably rememb] t ! friction to be ov]come p] squ>e foot ( surface increases ) ! dep?4 ,9 calculat+ reta9+ walls1 _m eng9e]s add ! weight ( ! soil to ! wat]1 & calculate = f #ij to #ajj lb4 p] cu4 ft4 ,! speak] is satisfi$ t 9 ! s-call$ ,new ,york quicks& x is suffici5t to use ! weight ( ! wat] only4 ,if ! s& increas$ ! side pressure above ! wat] pressure1 eng9e]s w\ld expect to use m compress$ air to hold x back1 :ile1 z a matt] ( fact1 ! air pressure us$ seldom v>ies mu* f t call$ = by ! hydro/atic head4 ,al?\gh all[ance = wat] pressure is suffici5t = design+ reta9+ walls 9 ,new ,york quicks&1 x is f> f suffici5t 9 c]ta9 silty mat]ials4 ,= in/ance1 9 ,m>yl&1 a c(f]-dam1 excavat$ to a dep? ( #cj ft4 9 silt & wat]1 _h ! bottom %ov$ 9 #b ft41 9 spite ( ! fact t ! wal+ pieces 7 #e ft4 ap>t v]tically at ! top & #c ft4 at ! bottom1 & 7 brac$ ) #ab by #ab-;94 timb]s1 e #g ft4 horizontally4 ,! wal+s split1 & ! cross-braces cut into ! wal+ pieces f #a to #b 942 9 o!r words1 ! pressure seem$ to be almo/ irresi/ible4 ,?is is q a contra/ to c]ta9 excavations 9 ,brooklyn1 :i*1 )\t any brac+ :atev]1 7 safely c>ri$ d[n #ae ft4 ,any eng9e] :o tries to guess at ! angle ( repose1 &1 f ! result+ calculations1 economizes on 8 bottom /ruts1 w f9d t soon] or lat] an accid5t on "o job w cause en\gh loss ( life & money to pay = cons]vative timb]s = ! re/ ( 8 life4 ,s mu* = side pressures4 ,z to ! pressure 9 ! ro( ( a tunnel1 probably e eng9e] w agree t almo/ any mat]ial except unfroz5 wat] w t5d to ar* m or less1 b h[ mu* x is impossible to say4 ,x is d\btful :e!r any exp]i5c$ eng9e] w\ld ev] try to c>ry all ! weight ov] ! ro(1 except 9 ! case ( back-fill1 & ev5 !n he w\ld h to make 8 own assumption 7:i* s\nds m polite ?an guess74 ,! au?or has /at$1 h[ev]1 t :5 ! tunnel ro( & sides are 9 place1 no fur!r tr\ble ne$ be fe>$4 ,on ! contr>y1 9 #ahhe1 ! ,canadian ,pacific ,railroad built a tunnel ?r\gh clayey mat]ial & l9$ x ) ord9>y #ab by #ab-;94 timb] fram+1 ab\t #b or #c ft4 ap>t4 ,aft] ! tunnel 0 complet$1 x collaps$4 ,x 0 re-excavat$ & l9$ ) #ab by #ab-;94 timb]s side by side1 & x collaps$ aga92 !n ! tunnel 0 ab&on$1 &1 = "s #bj ye>s1 ! track1 c>ri$ ar\nd on a #bc curve1 0 us$ until a new tunnel 0 built f>!r 94 ,?is tr\ble c\ld h be5 caus$ ei!r by ! slid+ or swell+ ( ! mat]ial1 & ! speak] is incl9$ to believe t x 0 caus$ by swell+1 = x is kn[n1 ( c\rse1 t mo/ mat]ial has be5 deposit$ by ,nature "u great pressure1 &1 by excavat+ 9 c]ta9 mat]ials1 ! air & moi/ure w\ld cause ^? mat]ials to swell & become an irresi/ible =ce4 ,to c>ry ! load1 ,mr4 ,meem pref]s to rely on ! po9ts ( ! piles r ?an ! side friction4 ,9 su* cases ! pile w\ld act z a po/1 & w\ld probably fail :5 ord9>ily load$1 unless firmly support$ at ! sides4 ,! speak] has se5 piles driv5 f #hj to #ij ft4 9 #aj m941 :i* (f]$ almo/ no resi/ance1 & yet1 a few days lat]1 !y w\ld su/a9 #dj tons ea*4 ,no "o w\ld dream ( putt+ #dj tons on a #ij-;ft4 pile re/+ on rock1 if x 7 n adequately support$4 ,x is ! speak]'s op9ion t brac+ %\ld n be omitt$ = ei!r piles or c(f]-dams4 ,,*>les ,e4 ,,gregory1 ,,assoc4 ,m4 ,,am4 ,,soc4 ,c4 ,e4--,9 describ+ 8 la/ exp]im5t ) ! hydraulic *amb]s & plung]1 ,mr4 ,meem /ates t1 aft] lett+ ! pressure /& at #be lb41 etc41 ! pi/on came up4 ,?is sugge/s t ! pi/on might h be5 rais$ at a mu* l[] pressure1 if x _h be5 all[$ to /& long en\gh4 ,! dep? & co>s5ess ( ! s& 7 n v>i$ to asc]ta9 :e!r any relation exi/s betwe5 !m & ! pressure requir$ to lift ! pi/on4 ,if ! pressure v>i$ ) ! dep? ( s&1 x w\ld indicate t ! r$uction 0 due to ! resi/ance ( ! wat] :5 f9ely divid$ by ! s&2 if x v>i$ ) ! co>s5ess ( ! s&1 z x und\bt$ly w\ld1 especially if ! s& gra9s 7 increas$ to sph]es #a 94 9 diamet]1 x w\ld %[ t x 0 indep5d5t ( ! voids 9 ! s&1 b dep5d5t on divid+ ! wat] into ?9 films4 ,! speak] believes t ! great] "p ( ! r$uction ( pressure on ! bottom ( ! pi/on might be bett] expla9$ by ! viscosity ( ! wat]1 ?an to assume t a consid]able "p ( ! plung] is n 9 contact ) x4 ,! wat]1 be+ divid$ by f9e s& into v ?9 films1 has a t5sile /r5g? :i* is capable ( resi/+ ! pressure = at lea/ a limit$ "t4 ,if ! wat] is capable ( ex]t+ its full hydro/atic pressure ?r\gh ! s&1 ! total pressure w\ld be ! full hydro/atic pressure on ! bottom ( ! pi/on :]e 9 contact1 &1 :]e sep>at$ f x by a gra9 ( s&1 ! pressure w\ld be decreas$ only by ! weight ( ! gra94 ,if a l>ge proportion ( ! top area ( a gra9 is 9 contact1 z assum$ by ! au?or1 ?is r$uction ( pressure w\ld be v small4 ,a correct int]pretation c be obta9$ only aft] m complete exp]im5ts h be5 made4 ,= horizontal pressures ex]t$ by saturat$ s&s on v]tical walls1 x has n be5 demon/rat$ t any?+ %\ld be d$uct$ f full wat] pressure4 ,no matt] h[ mu* ( ! area is 9 direct contact ) ! s& r ?an ! wat]1 ! full wat] pressure w\ld be transmitt$ ?r\gh ea* s& gra9 f its o!r side &1 if necess>y1 f & ?r\gh _m o!r gra9s :i* may be 9 turn 9 contact ) x4 ,! pressure on su* a wall w be wat] pressure ov] its entire surface1 &1 9 addition1 ! ?ru/ ( ! s& aft] correct+ = its loss ( weight 9 ! wat]4 ,! fact t small cavities may be excavat$ f ! sides ( tr5*es or tunnels back ( ! %eet+ proves only t !re is a local tempor>y ar*+ ( ! mat]ial1 or t ! cohesion ( ! p>ticles is suffici5t to )/& ! /ress tempor>ily1 or t !re is a comb9ation ( cohesion & ar*+4 ,! possibility ( mak+ su* excavations does n prove t pressure does n exi/ at su* po9ts4 ,t s& or e>? w ar* "u c]ta9 conditions has long be5 an accept$ fact4 ,! s& ar*es exp]im5t$ ) develop$ _! /r5g? only aft] consid]able yield+ &1 !re=e1 give no index ( ! di/ribution or int5sity ( /ress be=e su* yield+4 ,fur!rmore1 s& & e>? 9 ,nature are n con/ra9$ by =ms & re9=c+ rods4 ,mr4 ,meem's pap] is v valuable 9 t x pres5ts "s unusual ph5om5a1 b _m ( ! conclusions drawn !refrom _c be accept$ )\t fur!r demon/ration4 ,,francis ,w4 ,,p]ry1 ,,assoc4 ,m4 ,,am4 ,,soc4 ,c4 ,e4--,pressure-gauge obs]vations on a numb] ( pneumatic caissons rec5tly sunk1 ?r\gh v>i\s grades ( s&1 to rock at dep?s ( f #he to #aje ft4 bel[ gr\nd-wat]1 inv>iably %[$ work+-*amb] air-pressures equal1 z closely z c\ld be obs]v$1 to ! hydro/atic pressures comput$1 = correspond+ dep?s ( cutt+-edge1 z giv5 9 ,table #b4 ,^! obs]vations & computations 7 made by ! speak] 9 connection ) ! caisson f\ndations = ! ,municipal ,build+1 ,new ,york ,city4 ,,table #b4--;,,equival5t ,,feet ,,( ,,dep? ,,bel[ ,,wat] ,,p] ,,p\nd ,,pressure4 ,pressure1 ,equival5t ,equival5t ,obs]v$ 9 feet ( elevation pressure4 p\nds4 dep?4 = wat] at--#f4he4 ,m4,h4,w4 ,gr\nd-wat]4 #a #b4ca #i4jf ,practically #b #d4fc #aa4dh ! same z #c #f4id #ac4gi comput$ #d #i4be #af4aj = #e #aa4eg #ah4db gr\nd-wat]4 #f #ac4hh #bj4gc #g #af4ai #bc4jd #h #ah4ej #be4ce #i #bj4hb #bg4fg #aj #bc4ac #bi4ih #aa #be4dd #cb4bi #ab #bg4gf #cd4fa #ac #cj4jg #cf4ib #ad #cb4ch #ci4bc #ae #cd4gj #da4ee #af #cg4ja #dc4hf #ag #ci4cb #df4ag #ah #da4fc #dh4dh #ai #dc4ie #ej4hj #bj #df4bf #ec4aa #ba #dh4eg #ee4db #bb #ej4hi #eg4gd #bc #ec4bj #fj4je #bd #ee4ea #fb4cf #be #eg4hb #fd4fg #bf #fj4ad #ff4ii #bg #fb4de #fi4cj #bh #fd4gf #ga4fa #bi #fg4jh #gc4ic #cj #fi4ci #gf4bd #ca #ga4gj #gh4ee #cb #gd4ja #hj4hf #cc #gf4cc #hc4ah #cd #gh4fd #he4di #ce #hj4ie #hg4hj #cf #hc4bg #ij4ab #cg #he4eh #ib4dc #ch #hg4hi #id4gd #ci #ij4bj #ig4je #dj #ib4eb #ii4cg #da #id4hc #aja4fh #db #ig4ad #ajc4ii #dc #ii4df #ajf4ca #dd #aja4gg #ajh4fb #de #ajd4jh #aaj4ic #df #ajf4ci #aac4bd #cd ,,note4--,equival5t dep? 9 feet ------ pressure4 #ad4g ,e4,p4 ,,goodri*1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by lett]74--,?is pap] is to be *>act]iz$ by sup]latives4 ,p>ts ( x are believ$ to be exceptionally good1 :ile o!r p>ts are consid]$ equally dang]\s4 ,! au?or's exp]im5tal "w is extremely int]e/+1 & ! writ] believes ! results obta9$ to be ( great value2 b ! analytical "w1 bo? ma!matical & logical1 is emphatically que/ion$4 ,! writ] believes t1 9 ! design ( p]man5t /ructures1 consid]ation ( ar* action %\ld n be includ$1 at lea/1 n until mu* m in=mation has be5 obta9$4 ,he also believes t ! design ( tempor>y /ructures ) ?is inclusion is actually dang]\s 9 "s in/ances1 & takes ! lib]ty ( cit+ ! foll[+ /atem5t by ! au?or1 ) reg>d to 8 fir/ exp]im5t3 ,ab\t an h\r aft] ! sup]impos$ load _h be5 remov$1 ! writ] jo/l$ ! box ) 8 foot suffici5tly to dislodge "s ( ! expos$ s&1 :5 ! ar* at once collaps$ & ! bottom fell to ! gr\nd4 ,! writ] emphatically que/ions ! au?or's ideas z to ! ?ickness ( key :i* %\ld be all[$ ov] tunnels1 believ+ t conditions )9 an e>? mass1 except 9 v r>e in/ances1 are su* t true ar* action w seldom take place to any def9ite ext5t1 ?r\gh any consid]able dep?s4 ,fur!rmore1 ! au?or's reason = bisect+ ! angle betwe5 ! v]tical & ! angle ( repose ( ! mat]ial1 :5 he und]takes to det]m9e ! ?ickness ( key1 is n obvi\s4 ,?is assumption is %[n to be absurd :5 c>ri$ to ei!r limit1 = :5 ! angle ( repose equals z]o1 z is ! case ) wat]1 ?is1 me?od w\ld give a def9ite ?ickness ( key1 :ile !re c be absolutely no ar* action possible 9 su* a case2 &1 :5 ! angle ( repose is #ij1 z may be assum$ 9 ! case ( rock1 ?is me?od w\ld give an inf9ite ?ickness ( key1 :i* is aga9 se5 to be absurd4 ,x w\ld seem z if altoge!r too _m unkn[able conditions _h be5 assum$4 ,9 any case1 no ar* action c be br\ght into play until a c]ta9 am\nt ( settlem5t has tak5 place s z to br+ ! p>ticles into clos] contact1 & 9 su* a way t ! int]nal /resses are practically ^? only ( compression1 & ! %e>+ /resses are )9 ! limits possible = ! mat]ial 9 "q4 ,! au?or has repeat$ly made assumptions :i* are n borne out by ! application ( 8 ma!matical =mulas to actual extreme conditions4 ,?is me?od ( application to limit+ conditions is conc$$ly sometimes faulty2 b ! writ] believes t no e>? pressure !ory1 or "o conc]n+ ar* action1 c be consid]$ z satisfactory :i* does n apply equally well to hydraulic pressure problems :5 ! prop] assumptions are made z to ! factors = friction1 cohesion1 etc4 ,= example1 :5 ! angle ( repose is consid]$ z z]o1 9 ! au?or's fir/ =mula = ,w#a1 ! value becomes ,w#a1 :]eas x %\ld dep5d solely on ! dep?1 :i* does n ent] ! =mula1 & n at all on ! wid? ( op5+1 l1 :i* is ?us includ$4 ,! au?or has giv5 no exp]im5ts to prove 8 /atem5t t ! ar* ?ru/ is great] 9 dry] s&1 & ! accuracy ( ! /atem5t is que/ion$4 ,aga91 no reason is app>5t = assum+ ! direction ( ! rak]s 9 ,fig4 #c z t ( ! angle ( repose4 ,! writ] _c see :y t p>ticul> angle is repeat$ly us$1 :5 almo/ any o!r w\ld give results ( a simil> k9d4 ,! au?or has made no exp]im5ts :i* %[ any connection betwe5 ! angle ( repose1 z he int]prets x1 & ! l9es ( ar* action :i* he assumes to exi/4 ,) reg>d to ! illu/ration ( ! condition :i* is ?\ght to exi/ :5 ! mat]ial is compos$ ( l>ge b[l+ balls1 suppos$ly all ( ! same size1 ! writ] believes ! conclusion to be errone\s1 & t ?is c be readily se5 by inspection ( a diagram 9 :i* su* balls are repres5t$ z =m+ a pile simil> to ! well-kn[n pile ( %ells ( ! algebras1 9 ! diagram ( :i* a pile ( ?ree %ells1 re/+ on ! base1 has be5 omitt$4 ,x is !n se5 t unless ! pressures at an angle ( #fj ) ! horizontal are suffici5t to produce frictional resi/ance ( a v l>ge am\nt1 ! balls w roll & in/antly break ! ar* action sugge/$ by ! au?or4 ,consequ5tly1 an almo/ inf9itesimal settlem5t ( ! c5t]+ may cause ! complete de/ruction ( an ar* ( e>?4 ,! au?or's logic is believ$ to be entirely faulty 9 _m cases because he repeat$ly makes assumptions :i* are n 9 accordance ) demon/rat$ fact1 & f9ally sums up ! results by ! /atem5t3 ,x is conc$$ 7l9e #b1 p4 #ceg1 = example71 :5 ! writ]1 = "o1 has n ev5 conc$$ ! accuracy ( ! assumptions4 ,= in/ance1 ! au?or's well-kn[n !ory t pressures aga9/ reta9+ walls are a maximum at ! top & decrease to z]o at ! bottom1 is 9 absolute contradiction to ! results ( exp]im5ts conduct$ on a l>ge scale by ! writ] on ! new re9=c$ concrete reta9+ wall ne> ! ,/4 ,george ,f]ry1 on ,/at5 ,isl&1 ,new ,york ,city1 :i* w soon be publi%$1 & 9 :i* ! usual law ( increase ( lat]al pressure ) dep? is believ$ to be demon/rat$ beyond "q4 ,x mu/ be conc$$ t a consid]able ar* action 7s-call$7 actually exi/s 9 _m cases2 b x %\ld be equally conc$$ by ! advocates ( ! exi/5ce ( su* action t *anges 9 humidity1 due to mov+ wat]1 vibration1 & appreciable viscosity1 etc41 w inv>iably de/roy ?is action 9 "t4 ,9 consequ5ce1 ! au?or's reason+ 9 reg>d to ! pressures aga9/ ! faces ( reta9+ walls is believ$ to be op5 to grave "q z to accuracy ( assumption1 me?od1 & conclusion4 ,! au?or is correct 9 s f> z he assumes t ! "* ( ! /resses due to ! ?ru/ ( ! mat]ial w n *ange if brac+ %\ld be sub/itut$ = ! mat]ial 9 ! area designat$ by him1 etc41 provid$ he makes ! fur!r assumption t absolutely no motion1 h[ev] inf9itesimal1 has tak5 place meantime2 b1 unless su* motion has actually tak5 place1 no ar* action c h develop$4 ,an ar* ?ru/ c result only ) true ar* action1 t is1 ) /able abutm5ts1 & ! mass /ress$ :olly 9 compression1 ) correspond+ %ort5+ ( ! ar* l9e4 ,! ar* ?ru/ mu/ be proportional to ! ela/ic de=mation 7%ort5+7 ( ! ar* l9e4 ,if any su* ar* z is %[n 9 ,fig4 #e is assum$ to c>ry ! :ole ( ! weight ( mat]ial above x1 t assum$ ar* mu/ relieve all ! assum$ ar*es bel[4 ,!re=e ea* ( ! assum$ ar*es c c>ry no?+ m ?an its own mass4 ,o!rwise ! result+ ?ru/ w\ld increase ) ! dep?1 :i* is oppos$ to ! au?or's !ory4 ,turn+ aga9 to ! condition t ea* ar* c c>ry only its own weight3 if ^! ar*es are assum$ ( ?icknesses proportional to ! di/ance upw>d f ! bottom ( ! wall1 !y w be simil> figures1 & x is easily demon/rat$ t ! ?ru/ w !n be uni=m 9 am\nt ?r\gh\t ! :ole height ( ! wall1 except1 p]haps1 at ! v top4 ,?is condition is contr>y to ! au?or's ideas & also to ! facts z demon/rat$ by ! writ]'s exp]im5t on ! #dj-;ft4 reta9+ wall at ,/4 ,george4 ,consequ5tly1 ! au?or's /atem5t3 nor c anyone 99 99 99 d\bt t ! top timb]s are /ress$ m heavily ?an ^? at ! bottom1 is emphatically d\bt$ & e>ne/ly d5i$ by ! writ]4 ,fur!rmore1 ! assumption made by ! au?or z to ! t5d5cy ( ! mat]ial to slide s z to cause x to w$ge 99 99 99 betwe5 ! face ( ! %eet+ 99 99 99 & "s plane betwe5 ! %eet+ & ! plane ( repose1 is consid]$ z absolutely unw>rant$1 & consequ5tly ! :ole conclusion is believ$ to be unju/ifi$4 ,nor is ! au?or's assumption 7l9e #e1 p4 #cfa71 t ! ?ru/ 99 99 99 is measur$ by its weight divid$ by ! tang5t ( ! 99 99 99 angle ( repose at all obvi\s4 ,! au?or pres5ts "s v int]e/+ photographs %[+ ! natural surface slopes ( v>i\s mat]ials2 b x is int]e/+ to note t he describes ^! slopes z hav+ be5 produc$ by ! cont9ual slipp+ d[n ( p>ticles4 ,! va/ diff]5ce betwe5 angles ( repose produc$ 9 ?is mann] by ! roll+ friction ( p>ticles & ! int]nal angles ( friction1 :i* mu/ be us$ 9 all e>?-pressure inve/igations1 has be5 repeat$ly call$ to ! att5tion ( eng9e]s by ! writ]4,h ,! writ]'s exp]im5ts are entirely 9 accord ) ^? ( ! au?or 9 :i* ! latt] claims to demon/rate t e>? & wat] pressures act indep5d5tly ( ea* o!r1 & ! writ] is mu* delight$ t 8 own exp]im5ts h be5 ?us confirm$4 ,9 ,exp]im5t ,no4 #c1 ! qu]y is naturally sugge/$3 ,:at w\ld h be5 ! result if ! nuts & wa%]s _h fir/ be5 tight5$ & wat] !n add$8 ,al?\gh ! writ] has n tri$ ! exp]im5t1 he is r incl9$ to ! idea t ! ar* w\ld h collaps$4 ,) reg>d to ,exp]im5t ,no4 #e1 !re is to be not$ an int]e/+ possibility ( its application to ! !oretical discussion ( masonry dams1 9 :i* films ( wat] are assum$ to exi/ b5ea? ! /ructure or 9 crevices or cracks ( capill>y dim5sions4 ,! writ] has always consid]$ ! assumptions made by _m design+ eng9e]s z unnecess>ily cons]vative4 ,9 reg>d to ! au?or's conclusions f ,exp]im5t ,no4 #f1 x %\ld be not$ t no friction c exi/ betwe5 p>ticles ( s& & surr\nd+ wat] unless !re is a t5d5cy ( ! latt] to move2 & t wat] 9 motion does n ex]t pressures equal to ^? produc$ :5 9 a /atic condition1 ! r$uction be+ proportional to ! velocity ( fl[4 ,! au?or's conclusion 7p4 #cga71 t pressure w cause ! quicks& to set up hydraulic action1 does n seem to h be5 demon/rat$ by 8 exp]im5ts1 b to be only 8 !ory4 ,9 ?is in/ance1 ! results ( ! writ]'s exp]im5ts are contr>y to ! au?or's !ory & conclusion4 ,! writ] w he>tily add 8 prote/ to t ( ! au?or aga9/ consid]+ semi-aque\s masses1 su* z s\py s&s1 s(t concrete1 etc41 z ex]t+ hydro/atic pressure due to _! weight 9 bulk1 in/ead ( to ! specific gravity ( ! basic liquid4 ,aga91 simil>ly he>ty concurr5ce is giv5 to ! au?or's /atem5t3 ,if ! solid mat]ial 9 any liquid is agitat$1 s t x is virtually 9 susp5sion1 x _c add to ! pressure1 & if all[$ to subside x acts z a solid1 indep5d5tly ( ! wat] conta9$ ) x1 al?\gh ! wat] may *ange some:at ! prop]ties ( ! mat]ial1 by increas+ or *ang+ its cohesion1 angle ( repose1 etc4 ,on ! o!r h&1 x is believ$ t ! au?or's /atem5t1 z to ! t5d5cy ( m>bles to ar*1 a few l9es above ! "o la/ quot$1 %\ld be qualifi$ by ! addition ( ! words1 only :5 a c]ta9 am\nt ( deflection has tak5 place s z to br+ ! ar* into action4 ,aga91 on ! foll[+ page1 a some:at simil> qualification %\ld be add$ to ! s5t5ce ref]r+ to ! s(t clay ar*1 t x w\ld /& if ! rods support+ ! intrados ( ! ar* 7 key$ back to wa%]s cov]+ a suffici5tly l>ge area1 by ins]t+ ! words1 unless creep+ pressures 7su* z ^? enc\nt]$ by ! writ] 9 8 exp]im5ts7 7 exce$$4 ,! writ] consid]s z v d\btful ! =mula = ,dx1 :i* is ! same z t = ,w#a1 already discuss$4 ,! au?or's /atem5t t additional back-fill w "u c]ta9 circum/ances light5 ! load on ! /ructure1 is consid]$ subject to modification by "s su* clause z ! foll[+1 ! ^w 'light5' "h be+ und]/ood to mean ! r$uction to "s ext5t ( :at w\ld be ! total pressure due to ! comb9$ orig9al & add$ back-fill1 provid$ no ar* action occurr$4 ,! writ] is 9 entire agreem5t ) ! au?or z to ! probability t wat] is (t5 cut (f absolutely f its s\rce ( pressure1 ) ! att5dant results describ$ by ! au?or 7p4 #cgh72 & aga91 t too little att5tion has be5 giv5 to ! be>+ p[] ( soil1 ) ! au?or's accompany+ criticism4 ,! writ] _c see1 h[ev]1 :]e ! au?or's exp]im5ts demon/rate 8 /atem5t t pressure is transmitt$ lat]ally ?r\gh gr\nd1 mo/ probably along or ne>ly p>allel to ! angles ( repose1 or any ( ! conclusions drawn by him 9 ! p>agraph 7p4 #cha71 :i* conta9s ?is que/ionable /atem5t4 ,aga9 ! writ] is at a loss z to h[ to int]pret ! /atem5t t ! au?or has f\nd t bett] resi/ance has be5 (f]$ by small op5 caissons sunk to a dep? ( a few feet & clean$ out & fill$ ) concrete ?an by spread+ ! f\ndation ov] f\r or five times ! equival5t area4 ,! writ] agrees ) ! au?or 9 ! majority ( 8 /atem5ts z to ! be>+ value & friction on piles1 b believes t he is indulg+ 9 pure !ory 9 "s ( 8 succe$+ rem>ks1 :]e9 he ascribes to ar* action ! results :i* he believes w\ld be obs]v$ if a long %aft be )drawn v]tically f m\ld+ s&4 ,^! ph5om5a w\ld be due r to capill>y action & ! result+ cohesion4 ,naturally1 ! writ] d\bts ! au?or's conclusions z to ! pressure at ! top ( l>ge squ>e caisson %afts :5 he /ates t ! pressure at ! top 99 99 99 w 99 99 99 increase proportionately to ! dep?4 ,aga91 ! au?or is app>5tly n conv]sant ) exp]im5ts made by ! ,dock ,dep>tm5t ( ,new ,york ,city1 conc]n+ piles driv5 9 ! ,hudson ,riv] silt1 :i* %[$ t a s+le heavily load$ pile c>ri$ d[nw>d ) x o!r unload$ piles1 driv5 consid]able di/ances away1 %[+ t x 0 n ! pile :i* lack$ 9 resi/ance1 z mu* z ! surr\nd+ e>?4 ,9 conclusion1 ! writ] he>tily concurs ) ! /atem5t t too mu* has be5 tak5 = grant$ 9 connection ) e>? pressures & resi/ance1 & he is sorry to be =c$ to add t he believes ! au?or to be op5 to ! criticism :i* he himself sugge/s1 t bo? 9 exp]im5t+ & obs]v+1 ! eng9e] & 9 ?is case ! au?or w frequ5tly f9d :at is be+ look$ = or expect$ & w fail to see ! obvi\s alt]native4 ,,francis ,l4 ,,pruyn1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by lett]74--,mr4 ,meem %\ld be congratulat$1 bo? 9 reg>d to ! highly int]e/+ !ories :i* he advances on ! subject ( s& pressures--! pressures ( subaque\s mat]ial--& on 8 int]e/+ exp]im5ts 9 connection !re)4 ,! exp]im5t 9 :i* ! plung] on ! hydraulic ram is imm]s$ 9 s& & cov]$ ) wat] does n seem to be conclusive4 ,by ?is exp]im5t ! au?or attempts to demon/rate t ! pressure ( ! wat] transmitt$ ?r\gh ! s& is only ab\t #dj z great z :5 ! s& is n !re4 ,! travel ( gr\nd-wat] ?r\gh ! e>? is at times v sl[1 & occasionally only at ! rate ( f #b to #c ft4 p] h\r4 ,9 ! writ]'s op9ion1 ,mr4 ,meem's exp]im5t did n cov] suffici5t "t dur+ :i* ! pressure 0 ma9ta9$ at any giv5 po9t4 ,x is q probable t x may take #ae or #bj m94 = ! full pressure to be transmitt$ ?r\gh ! s& to ! bottom ( ! plung]1 & x is hop$1 !re=e1 t he w make fur!r exp]im5ts la/+ long en\gh to demon/rate ?is po9t4 ,9 reg>d to ! "q ( sk9 friction on caissons & piles1 x may be ( int]e/ to m5tion an exp]im5t :i* ! writ] made dur+ ! s9k+ ( ! l>ge caissons = ! ,williamsburg ,bridge4 ,^! caissons 7 ab\t #gj ft4 long & #ej ft4 wide4 ,! riv] bottom 0 ab\t #ej ft4 bel[ mean high wat]1 & ! caissons p5etrat$ s& ( good quality to a dep? ( f #ij to #ajj ft4 bel[ t level4 ,on two occasions calculations 7 made to det]m9e ! sk9 friction :ile ! caissons 7 be+ settl$4 ,) ! cutt+ edge f #bj to #cj ft4 bel[ ! riv] bottom1 ! calculations %[$ t ! sk9 friction 0 betwe5 #ejj & #fjj lb4 p] sq4 ft4 ,! writ] agrees ) ,mr4 ,meem t1 9 ! s9k+ ( caissons1 ! ar* action ( s& is1 9 a great measure1 de/roy$ by ! compress$ air :i* escapes "u ! cutt+ edge & p]colates up ?r\gh ! mat]ial close to ! sides ( ! caissons4 ,) ref]5ce to ! sk9 friction on piles1 ! writ] agrees ) ,mr4 ,meem t 9 c]ta9 classes ( mat]ial ?is is almo/ a negligible quantity4 ,! writ] has jack$ d[n #i-;94 pipes 9 v>i\s p>ts ( ,new ,york ,city1 & by plac+ a record+ gauge on ! hydraulic jack1 ! sk9 friction on ! pile c\ld be obta9$ v accurately4 ,9 sev]al in/ances ! gauge read+s did n v>y mat]ially f ! surface d[n to a p5etration ( #ej ft4 ,9 ^! in/ances ! mat]ial inside ! pipe 0 clean$ out to )9 #a ft4 ( ! bottom ( ! pile1 s t ! gauge read+ indicat$ only ! friction on ! outside ( ! pipe plus ! be>+ value develop$ by its l[] edge4 ,= a #i-;94 pipe1 ! sk9 friction on ! pile plus ! be>+ area ( ! bottom ( ! pipe seems to be ab\t #bj tons1 irrespective ( ! dep?4 ,aft] ! pipe _h rea*$ suffici5t dep?1 x 0 concret$1 &1 aft] ! concrete _h set1 ! jack 0 aga9 plac$ on x & gauge read+s 7 tak54 ,x 0 f\nd t 9 ord9>y s&s ! concret$ /eel pile w\ld g d[n f #c to #f 941 aft] :i* x w\ld br+ up to ! full capacity ( a #fj-ton jack1 %[+1 by gauge read+1 a reaction ( f #gj to #hj tons4 ,x is ! writ]'s op9ion t1 9 reasonably compact s&s situat$ at a dep? bel[ ! surface :i* w n all[ ( mu* lat]al movem5t1 a reaction ( #ajj tons p] sq4 ft4 ( area c be obta9$ )\t any difficulty :atev]4 ,,frank ,h4 ,,c>t]1 ,,assoc4 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by lett]74--,mr4 ,meem has contribut$ mu* t is ( value1 p>ticul>ly on wat] pressures 9 s&2 j :at result w\ld be obta9$ if co>se cru%$ /one or simil> mat]ial 7 sub/itut$ = s& 9 ,exp]im5t ,no4 #f1 is n obvi\s4 ,x has be5 ! practice lately1 among "s eng9e]s 9 ,bo/on1 z well z 9 ,new ,york ,city1 to assume t wat] pressures on ! und]side ( inv]ts is ex]t$ on "o-half ! area only4 ,! writ]1 h[ev]1 has made x a practice fir/ to lay a few in*es ( crack$ /one on ! bottom ( wet excavations 9 ord] to keep wat] f concrete :i* is to be plac$ 9 ! inv]t4 ,9 addition to ! crack$ /one "u ! inv]ts1 %all[ tr5*es dug lat]ally across ! excavation to insure m p]fect dra9age1 h be5 obs]v$4 ,bo? ^! factors no d\bt assi/ ! free c\rse ( wat] 9 ex]t+ pressure on ! f9i%$ inv]t aft] ! und]dra9s h be5 clos$ up on completion ( ! "w4 ,! writ]1 !re=e1 awaits ) int]e/ ! repetition ( ,exp]im5t ,no4 #f1 ) wat] on ! bottom ( a pi/on buri$ 9 co>se gravel or crack$ /one4 ,z = ! ar*+ effect ( s&1 ! writ] believes t ,mr4 ,meem has demon/rat$ an important pr9ciple1 on a small scale4 ,x mu/ be regrett$1 h[ev]1 t ! box 0 n made l>g]1 =1 to ! writ]1 x appe>s unsafe to draw su* sweep+ conclusions f small exp]im5ts4 ,z small models ( sailboats fail to develop completely laws = ! design & control ( l>ge rac+ ya*ts1 s exp]im5ts 9 small s& boxes may fail to demon/rate ! laws gov]n+ actual pressures on full-siz$ /ructures4 ,= "s "t ! writ] has be5 us+ a process ( reason+ simil> to t ( ! au?or = assumptions ( e>? pressure on ! ro(s ( tunnel ar*es1 except t ! v]tical =ces assum$ to hold up ! weight ( ! e>? h be5 ascrib$ to cohesion & friction1 along :at might be t]m$ ! sides ( ! tr5* excavation4 ,! writ] fails to f9d pro( 9 ?is pap] ( ! au?or's /atem5t t e>? pressures on ! sides ( a /ructure buri$ 9 e>? are great] at ! top ?an at ! bottom ( a tr5*4 ,t "s banks are top-heavy1 is1 no d\bt1 a fact1 ! writ] hav+ (t5 he>d simil> expressions us$ by exp]i5c$ tr5* =em51 b1 9 e case call$ to 8 att5tion1 local circum/ances h caus$ ! top-heav9ess1 ei!r und]m9+ at ! bottom ( ! tr5*1 too mu* bank$ e>? on top1 or ! e>? excavat$ f ! tr5* be+ too ne> ! edge ( ! cut4 ,= "s ye>s ! writ] has be5 mak+ ext5d$ obs]vations on deep tr5*es1 &1 ?us f>1 has fail$ to f9d evid5ce1 except 9 aque\s mat]ial1 ( e>? pressures :i* might be expect$ f ! kn[n natural slope ( ! mat]ial aft] exposure to ! elem5ts2 & ?is latt] feature may expla9 :y %eet$ tr5*es /& s mu* bett] ?an expect$4 ,if air _h free access to ! mat]ial1 cohesion w\ld be de/roy$1 & !oretical pressures w\ld be m easily develop$4 ,) closely-%eet$ tr5*es1 wea!r+ is practically exclud$1 & ! brac+1 :i* seem+ly is f> too light1 holds up ! tr5* ) sc>cely a m>k ( pressure4 ,z an in/ance1 9 #ahic1 ! writ] 0 successfully digg+ sew] tr5*es f #aj to #ad ft4 deep1 ?r\gh gravel1 9 ! c5tral "p ( ,connecticut1 )\t brac+2 because ( dem&s ( ! "w 9 ano!r "p ( ! city1 a l5g? ( sev]al hundr$ feet ( tr5* 0 left op5 = ?ree days1 result+ 9 ! cav+-9 ( ! sides4 ,! elem5ts _h de/roy$ ! cohesion1 & ! sides ( ! tr5*es no long] /ood v]tically4 ,rec5tly1 9 ! vic9ity ( ,bo/on1 tr5*es1 #cb ft4 wide1 & f #be to #ce ft4 deep1 ) heavy build+s on "o side1 h be5 brac$ ) #h by #aj-;94 /r+]s1 & brac]s at #aj-;ft4 c5t]s longitud9ally1 & f #c to #e ft4 ap>t v]tically2 ?is timb]+ app>5tly 0 too slight = pressures :i*1 !oretically1 might be expect$ f ! natural slope ( ! mat]ial4 ,j :at pressures develop on ! sides ( ! /ructures 9 ^! deep tr5*es aft] pull+ ! top %eet+ 7! bottom %eet+ be+ left 9 place7 is1 ( c\rse1 a matt] ( conjecture4 ,!re c be no d\bt t !re is an ar*+ ( ! mat]ial1 z sugge/$ by ! au?or4 ,h[ mu* ?is may be assi/$ by ! practical non-di/urbance ( ! virg9 mat]ial is1 ( c\rse1 indet]m9ate4 ,t sub/ructures & reta9+ walls design$ accord+ to ! ,rank9e or simil> !ories h an additional factor ( safety f too g5]\s an assumption 9 reg>d to e>? pressure is practically admitt$ ev]y:]e4 ,x is almo/ an eng9e]+ axiom t reta9+ walls g5]ally fail because ( insuffici5t f\ndation only4 ,= ! =ego+ reasons1 & p>ticul>ly f obs]vations on ! effect ( e>? pressures on wood5 timb]s us$ z brac+1 ! writ] believes t1 ord9>ily1 ! !oretical e>? pressures comput$ by ,rank9e & ,c\lomb are n realiz$ by "o-half1 & sometimes n ev5 by "o-?ird or "o-qu>t] 9 tr5*es well "u-dra9$1 rapidly excavat$1 & ?or\ghly brac$4 ,j4,c4 ,,meem1 ,m4 ,,am4 ,,soc4 ,c4 ,e4 7by lett]74--,! writ] has be5 mu* int]e/$ 9 ?is discussion1 & believes t x w be ( g5]al value to ! pr(ession4 ,x is un=tunate1 h[ev]1 t sev]al ( ! po9ts rais$ h be5 due to a c>eless read+ (1 or failure to und]/&1 ! pap]4 ,tak+ up ! discussion 9 detail1 ! writ] w fir/ answ] ! criticisms ( ,mr4 ,goodri*4 ,he says3 ,! writ] believes t1 9 ! design ( p]man5t /ructures1 consid]ation ( ar* action %\ld n be includ$1 at lea/1 n until m in=mation has be5 obta9$4 ,he also believes t ! design ( tempor>y /ructures ) ?is inclusion is actually dang]\s 9 "s in/ances4 ,if ! ar*+ action ( e>? exi/s1 :y %\ld x n be recogniz$ & consid]$8 ,! design ( timb]+ = a /ructure to re/1 = in/ance1 at a dep? ( f #bjj to #cjj ft4 9 normal dry e>?1 )\t consid]+ ?is action1 w\ld be virtually prohibitive4 ,mr4 ,goodri* proce$s to %[ "o ( ! dang]s ( consid]+ su* action by quot+ ! writ]1 z foll[s3 ,ab\t an h\r aft] ! sup]impos$ load _h be5 remov$1 ! writ] jo/l$ ! box ) 8 foot suffici5tly to dislodge "s ( ! expos$ s&1 :5 ! ar* at once collaps$ & ! bottom fell to ! gr\nd4 ,he fails1 z d s _m o!r critics ( ?is !ory1 to di/+ui% ! diff]5ce betwe5 t portion ( ! s& :i* acts z s-call$ c5t]+ & t :i* goes to make up ! su/a9+ ar*4 ,! dislodgm5t ( any l>ge portion ( ?is c5t]+ naturally causes collapse1 unless x is caught1 9 :i* case ! void 9 ! c5t]+ is fill$ f ! mat]ial 9 ! su/a9+ ar*1 & ?is1 9 turn1 is fill$ f t above1 & s on1 until ! /ability ( ea* ar* is 9 turn f9ally e/abli%$4 ,?is1 h[ev]1 does n mean t1 dur+ ! process ( e/abli%+ ?is equilibrium ( ! ar* /resses1 !re is no ar*+ action ( any ( ! mat]ial above1 b only t "s ( ! s-call$ ar*es are tempor>ily su/a9$ by ^? bel[4 ,t is1 9 effect1 ea* area ( ! mat]ial above becomes1 9 turn1 a dep5d5t1 an indep5d5t1 & f9ally an int]dep5d5t ar*4 ,if ,mr4 ,goodri*'s exp]i5ce has l$ him to exam9e any l>ge numb] ( tunnel ar*es or brick sew]s1 he w h not$ 9 _m ( !m longitud9al cracks at ! s(fits ( ! ar*es & p]haps else:]e4 ,^! result f ?ree causes3 ,fir/4--,9 tunnel+1 !re is m or less loss ( mat]ial1 :ile1 9 back-fill+1 ! mat]ial does n at fir/ rea* its f9al compactness4 ,!re=e1 9 adju/+ itself to normal conditions1 ?is mat]ial causes impact loads to come ^u ! gre5 ar*1 & ^! t5d to crack x4 ,second4--,no matt] h[ tightly a brick or o!r ar* is key$ 91 !re mu/ always be "s slight subsid5ce :5 ! c5t]s are /ruck4 ,?is1 aga91 results 9 a %ock1 or impact load+1 to ! detrim5t ( ! ar*4 ,?ird4--,! mo/ prolific cause1 h[ev]1 is t 9 tunnel+1 z well z 9 back-fill+ op5 cuts1 ! mat]ial back+ up ! haun*es is m or less loos5$ & !re=e is n at fir/ compact en\gh to prev5t ! spread+ ( ! haun*es :5 ! load comes on ! ar*4 ,?is causes crack+1 b1 z soon z ! haun*es h be5 press$ out aga9/ ! solid mat]ial1 ! crack+ usually ceases1 unless ! pressure has be5 suffici5tly heavy to cause collapse4 ,an int]e/+ example ( ?is 0 not$ 9 ! ,joralemon ,/reet bran* ( ! ,rapid ,transit ,tunnel1 9 ,brooklyn1 9 :i* a great _m ( ! ca/-iron r+s 7 crack$ "u ! cr[n ( ! ar*1 dur+ con/ruction2 b1 9 spite ( ?is1 !y su/a9$1 = m ?an two ye>s1 a load+ :i*1 accord+ to ,mr4 ,goodri*1 0 cont9ually increas+4 ,9 o!r words1 ! crack$ ar* su/a9$ a great] load+ ?an t :i* crack$ ! plates dur+ con/ruction1 accord+ to 8 !ory1 z not$ 9 ! foll[+ quotation3 ,b x %\ld be equally conc$$ by ! advocates ( ! exi/5ce ( su* action t *anges 9 humidity1 due to mov+ wat]1 vibration1 & appreciable viscosity1 etc41 w inv>iably de/roy ?is action 9 "t4 ,z to ! correctness ( ?is !ory ,mr4 ,goodri* w\ld probably h great difficulty 9 conv9c+ naturali/s1 :o are aw>e t _m animals live 9 enl>g$ burr[s ! /ability ( :i* is dep5d5t on ! ar*+ action ( ! e>?2 9 fact1 _m ( ^! burr[s h entrances "u wat]4 ,he w\ld also h "s difficulty 9 conv9c+ ^? exp]i5c$ m9]s :o1 aft] a cave-91 always wait until ! gr\nd has settl$ & compact$ itself be=e tunnel+1 usually ) app>5t safety1 ov] ! sc5e ( ! cave-94 ,! writ] quotes z foll[s f ,mr4 ,goodri*'s discussion3 ,9 any case1 no ar* action c be br\ght into play until a c]ta9 am\nt ( settlem5t has tak5 place s z to br+ ! p>ticles into clos] contact1 & 9 su* a way t ! int]nal /resses are practically ^? only ( compression1 & ! %e>+ /resses are )9 ! limits possible = ! mat]ial 9 "q4 ,fur!r3 ,consequ5tly1 an almo/ inf9itesimal settlem5t ( ! 'c5t]+' may cause ! complete de/ruction ( an ar* ( e>?4 ,& fur!r3 ,on ! o!r h&1 x is believ$ t ! au?or's /atem5t1 z to ! 't5d5cy ( m>bles to ar*1' 99 99 99 %\ld be qualifi$ by ! addition ( ! words1 'only :5 a c]ta9 am\nt ( deflection has tak5 place s z to br+ ! ar* into action4' ,9 a l>ge measure ! writ] agrees ) ! fir/ & la/ quotations1 b sees no reason to endorse ! second1 z x is impossible to consid] any ar* be+ built :i* does n settle slightly1 at lea/1 :5 ! c5t]s are /ruck4 ,reg>d+ 8 criticism ( ! lack ( ar*+ action 9 balls or m>bles1 he seems to reason t ! movem5t ( ! m>bles w\ld de/roy ! ar* action4 ,x is v difficult = ! writ] to conceive h[ x w\ld be possible = balls or m>bles to move :5 conf9$ z !y w\ld be conf9$ if ! e>? 7 compos$ ( !m in/ead ( its pres5t +r$i5ts1 & "u ! same conditions o!rwise4 ,mr4 ,goodri* c demon/rate ! correctness ( ! writ]'s !ories1 h[ev]1 if he w repeat ! writ]'s ,exp]im5t ,no4 #c1 ) m>bles1 ) buck%ot1 & ) dry s&4 ,he is also advis$ to make ! exp]im5t ) s& & wat]1 describ$ by ! writ]1 & is assur$ t1 if he w see t ! wa%]s are absolutely tight be=e putt+ ! wat] into ! box1 he c d ?is )\t br++ ab\t ! collapse ( ! ar*2 ! only ess5tial condition is t ! bottom %all be key$ up tightly1 s z n to all[ ! escape ( any s&4 ,he is also ref]r$ to ! two photographs1 ,plate ,,xxiv1 illu/rat+ ! writ]'s fir/ exp]im5t1 %[+ h[ increases 9 ! load+ result$ 9 compact+ ! mat]ial ( ! ar* & 9 ! consequ5t l[]+ ( ! false bottom4 ,z long z ! expos$ s& above ?is false bottom _h cohesion en\gh to prev5t ! collapse ( ! c5t]+1 ?is ar* c\ld h be5 load$ ) safety up to ! limits ( ! compressive /r5g? ( ! s&4 ,to quote aga9 f ,mr4 ,goodri*3 ,fur!rmore1 ! au?or's reason = bisect+ ! angle betwe5 ! v]tical & ! angle ( repose ( ! mat]ial1 :5 he und]takes to det]m9e ! ?ickness ( key1 is n obvi\s4 ,?is assumption is %[n to be absurd :5 c>ri$ to ei!r limit1 = :5 ! angle ( repose equals z]o1 z is ! case ) wat]1 ?is me?od w\ld give a def9ite ?ickness ( key1 :ile !re c be absolutely no ar* action possible 9 su* a case2 &1 :5 ! angle ( repose is #ij1 z may be assum$ 9 ! case ( rock1 ?is me?od w\ld give an inf9ite ?ickness ( key1 :i* is aga9 se5 to be absurd4 ,mr4 ,goodri* assumes t wat] or liquid has an angle ( repose equal to z]o1 :i* is true1 b ! writ]'s assumptions appli$ only to solid mat]ial1 & ! liquid gives an ess5tially diff]5t condition ( pressure1 z %[n by a c>eful read+ ( ! pap]4 ,9 solid rock ,mr4 ,goodri* assumes an angle ( repose equal to #ij1 = :i* !re is no au?ority2 t is1 solid rock has no kn[n angle ( repose4 ,9 ord] to c>ry ^! assumptions to a def9ite conclusion1 we mu/ assume = t mat]ial ) an angle ( repose ( #ij "s solid mat]ial :i* has weight b no ?ru/1 su* z blocks ( ice pil$ v]tically4 ,9 ?is case ,mr4 ,goodri* c readily see t !re w be no ar*+ action ov] ! /ructure1 & t ! requir$ ?ickness ( key w\ld be inf9ite4 ,z to ! o!r case1 x is some:at difficult to conceive ( a solid ) an angle ( repose ( z]o2 aque\s mat]ial does n fulfill ?is condition1 z x is ei!r a liquid or a comb9ation ( wat] & solid mat]ial4 ,! be/ illu/ration1 p]haps1 w\ld be to assume a mat]ial compos$ ( iron fil+s1 into :i* _h be5 driv5 a p[]ful magnet1 s t ! iron fil+s w\ld be drawn horizontally 9 "o direction4 ,x is easy to conceive1 !n1 t 9 tunnel+ ?r\gh ?is mat]ial !re w\ld be no necessity = hold+ up ! ro(2 ! def9ite ?ickness ( key giv51 z be+ at ! po9t ( int]section ( two #de angles1 w\ld be m]ely a precaution>y measure1 & w\ld n be requir$ 9 practice4 ,x is ?us se5 t bo? ^! conditions c be fulfill$ ) practical illu/rations2 t is1 = an angle ( repose ( #ij1 t mat]ial :i* has weight & no ?ru/1 & = an angle ( repose ( z]o1 t solid mat]ial :i* has ?ru/ b no weight4 ,mr4 ,goodri* says ! au?or has giv5 no exp]im5ts to prove 8 /atem5t t ! ar* ?ru/ is great] 9 dry] s&4 ,if ,mr4 ,goodri* w make ! exp]im5t p>tially describ$ z ,exp]im5t ,no4 #c1 ) absolutely dry s&1 & ) moi/ s&1 & on a scale l>ge en\gh to elim9ate cohesion1 he w probably f9d en\gh to conv9ce him t 9 ?is assumption ! writ] is correct4 ,at ! same "t1 ! writ] has bas$ 8 !ory 9 ?is reg>d on facts :i* are n entirely conclusive1 & 8 m9d is op5 z to :at future exp]im5ts on a l>ge scale may develop4 ,x is v probable1 h[ev]1 t an analytical & practical exam9ation ( ! ,engli% exp]im5ts not$ on pages #cgi & #chj1 w be suffici5t to develop ?is fact conclusively4 ,! writ] is =c$ to conclude t "s ( ! criticisms by ,mr4 ,goodri* result f a n too c>eful read+ ( ! pap]4 ,= in/ance1 he /ates3 ',x is conc$$' 7l9e #b1 p4 #ceg1 = example7 :5 ! writ]1 = "o1 has n ev5 conc$$ ! accuracy ( ! assumptions4 ,a m c>eful read+ w\ld h %[n ,mr4 ,goodri* t ?is concession 0 "o ( ! writ]'s z to c]ta9 pressures aga9/ or on tunnels1 &1 if ,mr4 ,goodri* does n conc$e ?is1 he is ev5 m radical ?an ! writ]4 ,& aga93 ',nor c anyone 99 99 99 d\bt t ! top timb]s are /ress$ m heavily ?an ^? at ! bottom' is emphatically d\bt$ & e>ne/ly d5i$ by ! writ]4 ,x is un=tunate t ,mr4 ,goodri* fail$ to make ! complete quotation1 :i* reads3 ,nor c anyone1 look+ at ,fig4 #e1 d\bt1 etc4 ,a glance at ,fig4 #e w demon/rate t1 "u conditions !re set =?1 ! writ] is probably correct 9 8 ass]tion z relat+ to t p>ticul> in/ance4 ,fur!r3 ,= in/ance1 ! au?or's well-kn[n !ory t ! pressures aga9/ reta9+ walls are a maximum at ! top & decrease to z]o at ! bottom1 is 9 absolute contradiction to ! results ( exp]im5ts conduct$ on a l>ge scale by ! writ] on ! new re9=c$ concrete reta9+ wall ne> ! ,/4 ,george ,f]ry1 on ,/at5 ,isl&4 ,! writ]'s well-kn[n !ory t pressures aga9/ reta9+ walls are a maximum at ! top & decrease to z]o at ! bottom applies only to pressures ex]t$ by absolutely dry & normally dry mat]ial1 & x seems to him t ?is s-call$ !ory is capable ( su* easy demon/ration1 by ! simple obs]vation ( any brac+ 9 a deep tr5* 9 mat]ial ( ?is class1 t x ought to be accept$ z at lea/ saf] ?an ! old !ory :i* x rev]ses4 ,z to ?is well-kn[n !ory 9 mat]ial subject to wat] pressure1 a c>eful read+ ( ! pap]1 or an exam9ation ( ,fig4 #ab & its accompany+ text1 or an exam9ation ( ,table #a1 w conv9ce ,mr4 ,goodri* t1 "u ! writ]'s analysis1 ?is pressure does n decrease to z]o at ! bottom1 b t 9 s(t mat]ials x may be approximately con/ant all ! way d[n1 :ile1 9 exceptionally s(t mat]ial1 conditions may arise :]e x may increase t[>d ! bottom4 ,! det]m9ation %\ld be made by tak+ ! solid mat]ial & dry+ x suffici5tly s t wat] does n fl[ or seep f x4 ,:5 ?is mat]ial is !n compact$ to ! condition 9 :i* x w\ld be 9 its natural /ate1 its angle ( repose may be measur$1 & may be f\nd to be z high z #fj degrees4 ,! v f9e matt] %\ld !n be sep>at$ f ! co>s] mat]ial1 & ! latt] weigh$1 to det]m9e its proportion4 ,subtract+ ?is f ! total1 ! rema9d] c\ld be cr$it$ to aque\s matt]4 ,x is ?us se5 t ) a mat]ial :5 p>tially dri$ 9 :i* ! natural angle ( repose might be #fj1 & 9 :i* ! p]c5tage ( wat] or aque\s matt] :5 subm]g$ might be #fj1 !re w\ld be an increase ( pressure t[>d ! bottom4 ,! writ] does n "k ! exact nature ( ! exp]im5ts made at ,/4 ,george's ,f]ry by ,mr4 ,goodri*1 b he supposes !y 7 measurem5ts ( pressures on pi/ons ?r\gh holes 9 ! %eet+4 ,he desires to /ate aga9 t he _c reg>d su* exp]im5ts z conclusive1 & believes t !y are ( comp>ative value only1 z su* exp]im5ts d n measure 9 any l>ge degree ! pressure ( ! solid mat]ial b only all or a portion ( ! s-call$ aque\s matt]1 t is1 ! liquid & v f9e mat]ial :i* fl[s ) x4 ,?us x is well kn[n t1 dur+ ! con/ruction ( ! rec5t ,hudson & ,nor? ,riv] ,tunnels1 pressures 7 te/$ 9 ! silt1 "s ( :i* %[$ t ! silt ex]t$ full hydro/atic pressure4 ,at ! same "t1 ,w4,i4 ,aims1 ,m4 ,am4 ,soc4 ,c4 ,e41 /at$ 9 a public lecture1 & rec5tly also to ! writ]1 t 9 #ahij he made "s te/s ( ! pressure ( ?is silt 9 normal air = ! late ,w4,r4 ,hutton1 ,m4 ,am4 ,soc4 ,c4 ,e4 ,a hole1 #ab 94 squ>e1 0 cut ?r\gh ! brickwork & ! iron l9+1 j back ( ! lock 9 ! nor? tube 79 normal air71 & ab\t #ajjj ft4 f ! ,new ,j]sey %ore4 ,x 0 f\nd t ! silt _h become s firm t x did n fl[ into ! op5+4 ,lat]1 a #d-;94 coll> & pi/on 7 built into ! op5+1 &1 dur+ a p]iod cov]+ at lea/ #c mon?s1 con/ant obs]vations %[$ t no pressure came ^u x2 9 fact1 x 0 /at$ t ! pi/on 0 frequ5tly work$ back & =? to induce pressure1 b no response 0 obta9$ dur+ all ?is p]iod4 ,! conclusion mu/ !n be drawn t :5 con/ruction1 ) its att5dant di/urbance1 has /opp$1 ! solid mat]ial surr\nd+ /ructures t5ds to compact itself m or less1 & solidify1 accord+ z x is m or less por\s1 =m+ 9 _m in/ances :at may be virtually a compact ar* %utt+ (f a l>ge p]c5tage ( ! normal1 & "s p]c5tage ev5 ( ! aque\s1 pressure4 ,t ! pressure ( normally dry mat]ial _c be measur$ ?r\gh small op5+s c be v]ifi$ by any "o :o w exam9e su* mat]ial back ( brac+ %[+ evid5ces ( heavy pressure4 ,! inve/igator w f9d t1 if ?is mat]ial is free f wat] pressure1 pap] /uff$ lightly into small op5+s w hold back indef9itely mat]ial :i* 9 l>ge masses has frequ5tly caus$ brac+ to buckle & %eet+ planks to b5d & break2 & ! writ] reit]ates t su* exp]im5ts %\ld be made 9 tr5*es %eet$ ) horizontal %eet+ be>+ aga9/ %ort v]tical rang]s & braces giv+ horizontal sections absolutely deta*$ & indep5d5t ( ea* o!r4 ,9 no o!r way c su* exp]im5ts be ( real value 7& ev5 !n only :5 made on a l>ge scale7 to det]m9e conclusively ! pressure ( e>? on tr5*es4 ,z to ! que/ions ( ! relative ?ru/ ( mat]ials "u v>i\s angles ( repose1 & ( ! necessity ( divid+ by ! tang5t1 etc42 ^!1 to ! writ]1 seem to be m]ely ! solution ( problems 9 simple graphics4 ,! writ] believes t if ,mr4 ,goodri* w make1 ev5 on a small scale1 "s ( ! exp]im5ts not$ by ! writ]1 he w be conv9c$ t _m ( ! assumptions :i* he _c at pres5t endorse are bas$ on fact1 & 8 co-op]ation w be welcom$ ) ! greate/ int]e/4 ,among ! exp]im5ts :i* he is ask$ to make is ! "o 9 dry s&1 not$ z ,exp]im5t ,no4 #c1 :]eby x c be %[n v conclusively t additional back-fill w result 9 increas$ ar*+ /ability1 on an ar* :i* w\ld collapse "u light] load+4 ,! writ] is indebt$ to ,mr4 ,goodri* = po9t+ out "s errors 9 omission & 9 typography 7n[ correct$71 & = 8 he>ty concurr5ce 9 "s ( ! assumptions :i* ! writ] believ$ w\ld meet ) greate/ disapproval4 ,9 reply to ,mr4 ,pruyn & ,mr4 ,gregory1 ! writ] assum$ t ! pi/on area 9 ,exp]im5t ,no4 #f %\ld be r$uc$ only by ! actual contact ( mat]ial ) x4 ,if ?is mat]ial 9 contact %\ld be compos$ ( !oretical sph]es1 result+ 9 a contact ) po9ts only1 !n ! !oretical area r$uc$ %\ld be 9 proportion to ?is am\nt only4 ,! writ] does n believe1 h[ev]1 t ?is condition exi/s 9 practice1 b ?9ks t ! area is r$uc$ v mu* m ?an by ! actual !oretical contact ( ! mat]ial4 ,he sees no reason1 z f> z he has gone1 to d\bt ! accuracy ( ! d$uctions f ?is exp]im5t4 ,reg>d+ ! "q ( ! l5g? ( "t requir$ to raise ! pi/on1 he does n believe t ! position ( 8 critics is entirely correct 9 ?is matt]2 t is1 x mu/ ei!r be conc$$ t ! pi/on area is cut (f f ! s\rce ( pressure1 or t x is 9 contact ) x ?r\gh m or less m9ute *annels ( wat]4 ,if x is cut (f1 !n ! writ]'s cont5tion is prov$ )\t ! ne$ ( ! exp]im5t1 & x is !re=e conclusive t a subm]g$ tunnel is n "u aque\s pressure or ! buoyant action ( wat]4 ,if1 on ! o!r h&1 ! wat] is 9 contact ?r\gh *annels be>+ directly ^u ! pi/on & lead+ to ! cle> wat] *amb]1 any increase 9 pressure 9 ! wat] *amb] mu/ necess>ily result 9 a virtually in/antane\s increase ( ! pressure aga9/ ! pi/on1 & !re=e ! action on ! latt] %\ld foll[ almo/ imm$iately4 ,9 all cases dur+ ! exp]im5ts ! pi/on did n respond until ! pressure 0 approximately twice z great z requir$ 9 cle> wat]1 !re=e ! writ] mu/ conclude ei!r t ! exp]im5ts prov$ x conclusively or t 8 assumption is prov$ )\t ! necessity ( ! exp]im5ts4 ,t is1 ! pressure is virtually n 9 evid5ce until ! pi/on has comm5c$ to move4 ,mr4 ,pruyn has add$ valuable in=mation 9 8 pres5tation ( data obta9$ f specific te/s ( ! be>+ value (1 & friction on1 holl[ /eel piles4 ,^! data l>gely corroborate te/s & obs]vations by ! writ]1 & are comm5d$ to g5]al att5tion4 ,mr4 ,c>t]'s in=mation is also ( special int]e/ to ! writ]1 z mu* ( x is 9 ! l9e ( confirm+ 8 views4 ,mr4 ,c>t] does n yet accept ! !ory ( increas$ pressure t[>d ! top1 b if he w exam9e or exp]im5t ) heavy brac+ 9 deep tr5*es 9 cle> s&1 or mat]ial ) well-def9$ angles ( repose1 he w probably f9d mu* to help him t[>d ! acceptance ( ?is view4 ,! writ] regrets t he has n n[ ! means or appliances = fur!r exp]im5ts ) ! pi/on *amb]1 b he does n believe t reliable results c\ld be obta9$ 9 brok5 /one ) s small a pi/on1 z x is possible t ! po9t ( "o /one only might be 9 contact ) ! pi/on4 ,?is w\ld naturally leave ! base expos$ almo/ :olly to a cle> wat] area4 ,he does n believe1 h[ev]1 t 9 practice ! lay+ ( brok5 /one "u inv]ts w mat]ially *ange ! ultimate pressure unless its cross-section repres5ts a l>ge area4 ,mr4 ,p]ry w f9d ! foll[+ on page #cfi3 ,x %\ld be not$ also t al?\gh ! area subject to pressure is dim9i%$1 ! pressure on ! area rema9+ corresponds to ! full hydro/atic head1 z w\ld be %[n by ! pressure on an air gauge4 ,?is1 ( c\rse1 dep5ds on ! porosity ( ! mat]ial & ! friction ! wat] meets 9 pass+ ?r\gh x4 ,z to ,mr4 ,?omson's discussion1 ! writ] notes ) regret two po9ts3 7a7 t specific data are n giv5 9 _m ( ! int]e/+ cases ( failures ( c]ta9 /ructures or brac+2 & 7b71 t he has n 9 all cases a cle> und]/&+ ( ! pap]4 ,= in/ance1 ! writ] has n advocat$ ! omission ( bottom brac+ or %eet+4 ,he has se5 _m in/ances :]e x has be51 or c\ld h be51 safely omitt$1 b he desires to make x cle> t he does n "u any circum/ances advocate its omission 9 good "w2 b only t1 9 well-design$ brac+1 its /r5g? may be decreas$ z x approa*es ! bottom4 ,ref]5ce is aga9 made to ! diagram1 ,fig4 #ab1 :i* %[s t1 9 mo/ cases ( c(f]-dams 9 comb9$ aque\s & e>? pressure1 !re may be ne>ly equal1 & 9 "s cases ev5 great]1 load+ t[>d ! bottom4 ,! writ] also specifically /ates t 9 air ! diff]5ce betwe5 aque\s & e>? pressure is pla9ly not$ by ! fact t brac+ is ne$$ s frequ5tly to hold back ! e>? :ile ! air is keep+ out ! wat]4 ,! lack ( specific data is especially noticeable 9 ! acc\nt ( ! rise ( ! #f-;ft4 conduit at ,toronto4 ,x w\ld be ( great int]e/ to "k ) c]ta9ly ! weight ( ! pipe p] foot1 & :e!r x 0 prop]ly b$d$ & prop]ly back-fill$4 ,9 all probability ! back-fill+ ov] c]ta9 areas 0 n prop]ly done1 & z ! pipe 0 expos$ to an upw>d pressure ( ne>ly #afjj lb4 p] ft41 ) probably only #ejj or #fjj lb4 ( weight to c\nt]balance x1 x c readily be se5 t x did n con=m ) ! writ]'s g5]al sugge/ion1 t /ructures n compactly1 or only p>tially1 buri$1 %\ld h a l>ge factor ( safety aga9/ ! upw>d pressure4 ,oppos$ to ,mr4 ,?omson's exp]i5ce 9 ?is in/ance is ! fact t (t5times ! tunnels "u ! ,ea/ ,riv] approa*$ v close to ! surface1 ) ! mat]ial above !m s s\py 7ow+ to ! escape ( compress$ air7 t _! upp] surfaces 7 tempor>ily 9 wat]1 yet !re 0 no in/ance 9 :i* !y rose1 al?\gh "s ( !m 7 "u excessive buoyant pressure4 ,x is also ( int]e/ to note1 f ! pap]s descriptive ( ! ,nor? ,riv] ,tunnel1 t1 ) %ield doors clos$1 ! %ield t5d$ to rise1 :ile by op5+ ! doors to take 9 muck ! %ield c\ld be br\ght d[n or kept d[n4 ,! writ] concurs ) ^? :o believe t ! ris+ ( ! %ield ) clos$ doors 0 due to ! slightly great] d5sity ( ! mat]ial bel[1 & 0 n 9 any way due to buoyancy4 ,conc]n+ ! collapse ( ! brac+ 9 ! tunnel built "u a side-hill1 ! writ] believes x 0 due to ! fact t x 0 "u a slid+ side-hill1 & t1 if x _h be5 possible to h back-fill$ ov] & above ?is tunnel to a v l>ge ext5t1 ?is back-fill w\ld h result$ 9 *eck+ ! slid+ ( mat]ial aga9/ ! tunnel1 & ! "w w\ld !reaft] h be5 done ) safety4 ,?is is corroborat$ by ,mr4 ,?omson's /atem5t t ! tunnel 0 subsequ5tly c>ri$ ?r\gh safely by go+ f>!r into ! hill4 ,z to ! angle ( repose1 ,mr4 ,?omson seems to feel t its det]m9ation is s (t5 impracticable t x is n to be reli$ on2 & yet all calculations p]ta9+ to e>? pressure mu/ be bas$ on ?is factor4 ,! writ] believes t ! angle ( repose is n difficult to det]m9e1 & t obs]vations (1 & exp]im5ts on1 expos$ banks 9 simil> mat]ial1 & g5]al exp]i5ce 9 relation !reto1 w enable "o to det]m9e x 9 ne>ly all cases )9 su* reasonably accurate limits t only a small m>g9 ( safety ne$ be add$4 ,eng9e]s are s5t to ,europe to /udy sewage disposal1 wat] purification1 transit problems1 etc41 b are r>ely s5t to an adjo9+ c\nty or ,/ate to look at an expos$ bank1 :i* w\ld p]haps solve a vex$ problem 9 brac+ & result 9 great economy 9 ! design ( p]man5t /ructures4 ,mr4 ,?omson's g5]al views seem to indicate t mu* ( ! subject matt] not$ 9 ! pap] relates to unsolvable problems1 = x appe>s t 9 _m cases he believes ! ,eng9e] to be dep5d5t on 8 educat$ guess1 back$ p]haps by ! exp]i5c$ guess ( ! =eman or practical man4 ,! writ]1 on ! contr>y1 believes t e problem relat+ to "w ( ?is class is capable ( be+ solv$1 )9 reasonably accurate limits1 & t ! "t is n f> di/ant :5 ! eng9e]1 ) 8 /udy ( conditions1 & samples ( mat]ial be=e him1 w be able to solve 8 e>? pressure & e>? resi/ance problems z accurately z ! bridge eng9e]1 ) 8 k ( /ructural mat]ials1 solves bridge problems4 ,! writ]1 9 ! c\rse ( 8 exp]i5ce1 has met ) or be5 int]e/$ 9 ! solution ( _m problems simil> to ! foll[+3 ,:at diff]5ce 9 timb]+ %\ld be made = a tunnel 9 ord9>y1 normally dry gr\nd at a dep? ( #bj ft4 to ! ro(1 z comp>$ ) "o at a dep? ( #ij ft48 ,:at diff]5ce 9 timb]+ or 9 p]man5t design %\ld be made = a horizontally-%eet$ %aft1 #e ft4 squ>e1 go+ to a dep? ( #de ft4 & "o #be by #gj ft41 = in/ance1 go+ to ! same dep?1 assum+ ea* to be brac$ & %eet$ horizontally ) indep5d5t brac+8 ,:at all[ance %\ld be made = ! /r5g? ( int]lock1 assum+ t a circul> bulkhead ( s&1 #cj ft4 9 diamet]1 is to be c>ri$ by /eel %eet-pil+ expos$ ar\nd ! outside = a dep? ( #dj ft48 ,:at av]age pressure p] squ>e foot ( area %\ld be requir$ to drive a section ( a #c by #ae-;ft4 ro( %ield1 z comp>$ ) ! pressure ne$$ to drive ! :ole ro( %ield ) an area f\r times z great8 ,to :at dep? c\ld a #ab by #ab-;94 timb] be driv51 "u gradually add$ pressure1 up to #fj tons1 = in/ance1 9 normal s&8 ,:at frictional resi/ance %\ld be assum$ on a holl[1 /eel1 smoo?-bore pile :i* _h be5 driv5 ?r\gh %>p s& & _h p5etrat$ s(t1 m>%y mat]ial ! be>+ resi/ance ( :i* 0 practically valueless8 ,:at all[ance %\ld be made = ! buoyancy ( a tunnel #bj ft4 9 diamet]1 ! top ( :i* 0 buri$ to a dep? ( #bj ft4 9 s& above :i* !re 0 #dj ft4 ( wat]8 ,x is believ$ by ! writ] t mo/ ( ! au?orities are sil5t z to ! solution ( problems simil> to ! above1 & x is because ( ?is lack ( available data t he has direct$ 8 /udies to !m4 ,! belief t ! results ( ^! /udies1 toge!r ) su* obs]vations & exp]im5ts z relate !reto1 may be ( int]e/1 has caus$ him to set !m =? 9 ?is pap]4 ,he desires to /ate 8 belief t if problems simil> to ! above 7 giv5 = def9ite solution1 n bas$ on ord9>y safe practice1 & )\t conf]5ce1 to a numb] ( eng9e]s prom95tly int]e/$ 9 su* matt]s1 ! results w\ld v>y s widely z to conv9ce "s ( ! critics ( ?is pap] t ! great] dang] lies r 9 ! non-exploration ( su* fields ?an 9 ! sett+ =? ( results ( exploration :i* may appe> to be some:at radical4 ,fur!r1 if ^! views result 9 /imulat+ en\gh int]e/ to lead to ! hope t ev5tually ! ,pressure1 ,resi/ance1 & ,/ability ( gr\nd "u v>y+ conditions w be kn[n )9 reasonably accurate limits & tabulat$1 ! writ] w feel t 8 ef=ts h n be5 9 va94 ,,footnotes3 ,footnote ,h3 ,lat]al ,e>? ,pressures & ,relat$ ,ph5om5a1 ,transactions1 ,am4 ,soc4 ,c4 ,e41 ,vol4 ,,liii1 p4 #bgb4