Analysis of Spatial Effects of Two-row Pile Structure of Foundation Pit Based on Elastic Resistance Method

Transcription

1 Interntionl Journl o ivil & Environmentl Engineering IJEE-IJENS Vol: No: Anlsis o Sptil Eects o Two-row Pile Structure o Fountion Pit se on Elstic Resistnce Metho YUAN Mn ; DING Jihui b ; ZHANG Qin c ollege o ivil Engineering Hebei Universit, oing, Hebei, P.R.hin, 7 erommee@.com; b ingjihui@.com; c xviervon@gmil.com Receive **** Abstrct-- The two-row-pile retining n protecting structure o eep ountion pit is complex three imension sptil problem, while the nlsis n clcultion in tritionl esign ws bse on two-imensionl plne strin theor; the sptil n time eects re not relecte. The concept o erth pressure utilition ctor is propose n clcultion metho is estblishe bse on elstic resistnce metho. Assume tht horiontl isplcement o top bem hs n pproximte unction with simple supporte bem subjecte uniorm lo, the utilition ctor o erth pressure n eormtion o two-row-pile brcing structure re clculte. Prcticl exmples o two-row-pile brcing projects shows tht clcultion metho o utilition ctor o erth pressure in consiering sptil eect propose is esible. Inex Term-- Sptil eect, Deep ountion pit, Utilition ctor o erth pressure, Two-row pile structure. INTRODUTION With the evelopment o ountion pit engineering, the ouble-row pile brcing structures re wiel pplie. Deep ountion pit is complex three imension sptil problem. Through monitoring or the sot soil pit o some high-rise builing, Fook-Hou Lee thought stiness eect o pit corner m gretl ecrese the eormtion o the brcing structure n settlement o soil ler. se on soil plsticit upper boun theor n limit equilibrium nlsis theor, Yng Xue-qing iscusse excvtion ens shieling eect rom soil pressure cte on supporting structure, n gve out soil pressure clculting ormul combine with sptil eect. onsiering sptil mutul interction n eormtions mong ring bem, mile bems, row o piles, brces n ountion soil in the eep excvtion structure, Li Gun-hou set up the -D inite element nlsis moel bse on the mutul eormtion theor; n settle speciic metho to clculte the equivlent ountion stiness n erth pressure. Hn Sen use three methos to clculte the coeicient n intensit o erth pressure, which inclue the metho consiering ngle o internl riction cn be suit or over consolite soil, normll consolite soil n uner consolite soil. Ding Ji-hui n Zhng Qin gve clcultion metho o soil pressure utilition ctor on cntilever supporting structure o eep Excvtion n the conventionl esign metho consiere the sptil eect o eep ountion excvtion. se on elstic resistnce metho, the concept n computtion metho o the soil pressure utilition ctor or supporting structure o eep ountion re introuce, n the sptil istribution o the eormtion re given.. EARTH PRESSURE UTILIZATION FATOR OMPUTATION.. Erth Pressure As shown in Fig., ctive erth pressure on the two-row pile supporting structure is compute s soil volume rtio metho. Accoring to the pile rrngement the erth pressure is compute s ollow. plum rrngement pile: p ( ), pb ( ) () rectngle rrngement pile: p, pb ( ) () L/ L L () ( L/ ) ( q ) K c K () where, is the proportion coeicient, is Rnkine s ctive erth pressure, p is the ctive erth pressure cte on the ront-row-pile, b p is the ctive erth pressure cte on the bck-row-pile, c n re the soil strength inexes. 7- IJEE-IJENS October IJENS

2 h h h Interntionl Journl o ivil & Environmentl Engineering IJEE-IJENS Vol: No: A L L D Pb M Q h h - Õ/ P E SLIP-SURFAE P Ph Pbho h h A F () ouble-row pile M Q P Ph (b) ront-row-pile o E M F Q D Pb Pbho (c) bck-row-pile Fig.. erth pressure computtion igrm Due to the sptil eect o ountion excvtion, ctive erth pressure is given prtl scope to. The rel ctive erth pressure is K () Where, is ctive erth pressure utilition ctor... Deormtion omputtion o Supporting Structure As shown in Fig., the supporting structure o the ountion pit is ivie into two prts to seek solution. The prt o the supporting structure upper the slie plne o the ountion pit is tken s cntilever bem to solve, n the nother prt uner the slie plne o the ountion pit is tken s bem with ierent supporting to solve using elstic resistnce metho (tht is the M metho). Using the M metho, the stiness coeicient o the soil bo is k m. Where m is the rtio s technicl Speciiction to choose vlue. Fig.. M metho computtion igrm As shown in Fig., The prt o the supporting structure uner the slie plne o the ountion pit is stisie the ierentil eqution EI mb p b () Where, p ( q H) c Let mb EI, the eqution () is simpliie EI [( q H ) c ] b x (7) Where, is the lterl isplcement o the pile. b is the clcultion with o the pile. m is the rtio s technicl Speciiction to choose vlue[]. Using to Power Series to solve the eqution (7), the solution orm is n (8) n n Eqn. (8) substituting into Eon. (7) gives ) ( ) Where, ( k ( ) k ()! k ( ) ( ) k ( )! k ( ) ( ) k ( )! k ( ) ( ) k ( )! (9) 7- IJEE-IJENS October IJENS

3 Interntionl Journl o ivil & Environmentl Engineering IJEE-IJENS Vol: No: k ( ) ( ) k ( )! ( q h) c EI The unknown constnt i ( i,,, ) is ecie b bounr conitions. The bounr conitions o the excvtion surce o the ountion pit re EI( '') M, EI( ''') H () Eqn. ( ) substituting into Eqn. (9) gives H / EI, M / EI () The unknown constnt n re ecie b bounr conitions o the pile bottom. The bounr conition o the pile bottom is simpliie ree en, ixe hinge n ixe en ccoring to the epth burie uner the soil. The re Free en: EI ( ''), EI ( ''') () h Fixe hinge: ( ) h h EI, ( '') EI () h Fixe en: EI ( ), EI ( ') () h h Accoring to the rel engineering, the bounr conition o the pile bottom is selecte, n the eormtion n internl orce o the supporting structure uner the slie plne o the ountion re solve s ollow. The ngle o rottion: ' ' ' ' ' () The bening moment: M EI EI[ ] () The sher orce: V EI EI[ ] (7) Pssive erth pressure: p mb mb[ ( ) ( ) ( ) ( ) ( )] (8) The eormtion n internl orce upper the slie plne o the ountion is me s cntilever bem uner istribute los. Using the superposition metho the isplcement curve o the top o supporting structure cn be obtine. Assuming tht top bem pplies xil orce n bening moment to the pile top o ront-row-pile n bck-row-pile, s shown in Fig. (b) n (c). The horiontl isplcement n ngle o rottion o the pile top o ront-row-pile re equl to those o bck-row-pile, the xil orce n bening moment the pile top o ront-row-pile n bck-row-pile re obtine... Erth Pressure Utilition Fctor omputtion Knowing the mesure (llowe) isplcement o the top o the retining structure w, using conition w w, the eqution o utilition ctor o erth pressure cn be obtine, n thn solve this eqution, cn be obtine. Knowing the mesure(llowe) horiontl isplcement curve o the top o the retining structure, s the bove metho, the sptil istribution o erth pressure utilition ctor cn be obtine. I the mesure (llowe) horiontl isplcement curve o the top o the supporting structure re not hven, the sptil istribution o utilition ctor o erth pressure is solve through ssuming the simple supporte top bem subjecte horiontl uniorm los. The horiontl pproximte isplcement o the top bem hs Ax( l lx x ) (9) Where, A is unknown constnt which is ecie s the mesure (llowe) isplcement o the mile bem. Accoring eqn. (9) n prt., the sptil istribution o erth pressure utilition ctor cn be solve.. ENGINEERING EXAMPLE As shown in Fig., The builing ountion pit in Hnn Hebei,pit epth is 8.m, prtl.m, the supporting orm is ouble-row piles. The pile rius is mm, pile length is.m. The soil lers long pile length re: mixe ill soil: 7.N/m, c kp, h.8m; silt cl: 9.N/m, c.p,., h.m; sn cl: 9.N/m, c 7.kP, 9., h.m; silt cl: 8.N/m, c.kp, 8., h.m; cl: 9. N/m, c P,., h.m; ine sn: 8.9 N/m, c.p,, h.m. The elstic moulus o the weighte men vlue o soil lers is 89.P. pile: concrete is, reinorcing br is φ, top bem: with thick cm cm, concrete, rrngement o piles n testing point re shown Fig... The pile length o the bck-row-pile upper slie plne h. m, the volume proportion coeicient., 7- IJEE-IJENS October IJENS

4 /m /m Interntionl Journl o ivil & Environmentl Engineering IJEE-IJENS Vol: No: equivlent stiness EI 98kN.m, m kn/m. The bottom bounr conition o ront-row-pile n bck-row-pile re simpliie ixe en. omputtion results re shown in Fig.~ Fig. 7. the ront n bck-row pile is greter 8.mm thn mesuring results, n the bottom o the pit is less thn rnge -mm. As shown in Fig.,the computtion eormtions o the simple supporte top bem long north sie o ountion pit is lrger thn mesuring eormtion, but ner the corner two results is ver ner x / m.. Disp. o top bem. [] Limite equilibrium metho ouble-row pile _ M- metho Erth pressure cse.. Fig.. The sptil istribution o the ctive erth pressure utilition ctor o north sie Pit Fig.. Pile rrngement o Fountion Pit - / mm / mm 8 Front-row-pile -- M metho ck-row-pile -- M metho Front-row-pile -- mesuring ck-row-pile -- mesuring 8 8 Front-row-pile -- M metho ck-row-pile -- M metho Front-row-pile -- mesuring ck-row-pile -- mesuring 8 Fig.. Mile Prt Displcement o North Sie Pit x /m /m....8 Mesuring M metho Fig.. Top Deormtion o north sie Pit As shown in Fig.,the. computtion results re correspon to mesuring lw, the spee o eormtion is ster thn mesuring results o the ront-row-pile n bck-row-pile. omputtion isplcement o the top o Fig. 7. Mile Prt Displcement o South Sie Pit The sptil istribution o the ctive erth pressure utilition ctor o north sie Pit is shown in Fig.. the ctive erth pressure utilition ctors given b reerence[], which two-row pile structure o ountion pit is simpliie cntilever wll n the limite equilibrium metho is opte, re close to the pper s results. Accoring to the sptil istribution o the ctive erth pressure utilition ctor, the two-row pile structure esign o ountion pit is optimie. Accoring to the mesuring isplcement o the mile prt in the south o ountion pit, the utilition ctor o ctive erth pressure is.8, n using this result the isplcement o the mile prt is computte shown in Fig. 7. The computtion n mesuring isplcement re ner uner o the ountion pit surce, n the computtion isplcement o the top structure is lrger mm. There is worl o ierence between the computtion n mesuring isplcement upper o the ountion excvtion surce. 7- IJEE-IJENS October IJENS

5 Interntionl Journl o ivil & Environmentl Engineering IJEE-IJENS Vol: No:. ONLUSION se on elstic resistnce metho o the two-imensionl plne strin problem, the concept n computtion metho o the soil pressure utilition ctor or supporting structure o two-row-pile ountion pit re introuce, n the sptil istribution o the eormtion re given. Assume the horiontl isplcement o the top bem hs the sme unction orm with the simple supporte bem subjecte to the uniorm lo, thereore, utilition ctor o ctive erth pressure, retining structure eormtion n sptil istribution o inner orce on ouble-row-pile retining n protecting structure re clculte. The prcticl exmples o ouble-row-pile supporting projects shows tht the isplcement unction o the simple supporte top bem is nerer to the mesuring results, there is little ierence between the computtion n mesuring isplcement upper o the ountion excvtion surce. REFERENES [] Ding Ji-hui, Zhng Qin. lcultion Metho o Soil Pressure Utilition Fctor on ntilever Supporting Structure o Deep Excvtion. Interntionl Workshop on Architecture, ivil n Environmentl Engineering, AEE(Wuhn, hin),.. (in hinese) [] Fook-Hou Lee,Kwet-YewYong,Kevin. N. Qun,etc. Eect o orners in Structte Excvtions: Fiel Monitoring n se Histories [J]. Journl o Geotechnicl Engineering. 998, 9-9. [] Hn Sen, Zheng Yi. Stu on the omputtion Methos or oeicient o Erth Pressure in Fountion Pit rcing [J]. Soil Engineering n Fountion., 9(): -. (in hinese) [] JGJ -99 Technicl Speciiction or Retining n Protection o uiling Fountion Excvtions, eijing: hin Architecture Innustr Press, 999. (in hinese) [] Li Gun-hou, Fng Ying-gung n Shi Hung-n. Sptil mutul eormtion nlsis metho or row o piles o eep excvtion [J]. Rock n Soil Mechnics. 7,8(8): (in hinese) [] Nie Qing-ke, Ling Jin-guo. Design Theor n Appliction on Two-row pile suporting strcture o eep Fountion Excvtion[M]. eijing: hin Architecture Innustr Press, 8. (in hinese) [7] Yng Xue-qing, Liu Zu-e. Reserch bout sptil eect o eep pit supporting[j]. hinese Jounl o Geotechnicl Engineering, 998.,():7-78. (in hinese) 7- IJEE-IJENS October IJENS