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1、河海大學(xué)碩士學(xué)位論文復(fù)合地基中剛性樁刺入及沉降變形理論分析姓名:仇亮申請學(xué)位級(jí)別:碩士專業(yè):巖土工程指導(dǎo)教師:施建勇20060501摘要?jiǎng)傂詷稄?fù)合地基理論研究的重點(diǎn),主要集中在兩個(gè)方面:一.樁土共同作用下的荷載傳遞規(guī)律,二.下臥層的應(yīng)力及變形特性。本文從剛性樁在飽和軟粘土體中的貫入問題入手,對剛性樁復(fù)臺(tái)地基的位移場和應(yīng)力場作了相應(yīng)的研究,得到了一些有意義的結(jié)論。主要工作包括如下方面:1.以應(yīng)變路徑法模擬樁端的準(zhǔn)靜態(tài)深刺入過程.以其中應(yīng)變完備解答為基礎(chǔ),采用Drucker--Prager屈服準(zhǔn)則及流動(dòng)準(zhǔn)則,推導(dǎo)了樁端塑性區(qū)域內(nèi)各應(yīng)力分量的理論表達(dá)式;結(jié)合平衡方程以及有無附加應(yīng)力影響下的塑性區(qū)
2、邊界條件,給出了塑性區(qū)域內(nèi),特殊路徑下,包括體積應(yīng)力在內(nèi)的應(yīng)力分量顯式解答。2.結(jié)合符合柔性基礎(chǔ)下剛性樁復(fù)合地基中土體附加應(yīng)力分布規(guī)律,采用應(yīng)變路徑法模擬樁端刺入,描述了考慮附加應(yīng)力影響下的樁端及樁端附近區(qū)域土體的應(yīng)力應(yīng)變變化過程。并分析了反映軟土特性的重要指標(biāo)如摩擦角、剛度指數(shù)等對樁端應(yīng)力分布的影響。3.結(jié)合現(xiàn)有的側(cè)摩阻力經(jīng)驗(yàn)表達(dá)式,推導(dǎo)樁身應(yīng)力平衡方程,考慮剪切應(yīng)力影響下的樁間土位移協(xié)調(diào)方程。假定樁相對土體不可壓縮,給出了剛性樁復(fù)合地基沉降的理論解答。并分析了土體參數(shù)、置換率等因素對復(fù)合地基性狀的影晌。關(guān)鍵詞:剛性樁復(fù)合地基,柔性基礎(chǔ),應(yīng)變路徑法,刺入變形,下臥層沉降A(chǔ)bstractT
3、hestudyofcompositegroundofrigidpileisconcentratedonthefollowingtwomainpoints:thefirstistheloadtransferlawbetweenpileandsoil,thesecondisthebehaviorofthesoilresistanceatthepiletip.Startingwiththepenetrationofthepileintothesaturatedclays,Thenonlinearbehaviorofthesoilresistanceatthepiletipinthestudyis
4、predicted.Theworkincludestheseveralmainpointsasfollows:1Thispaperdescribesthefundamentalsofthestrainpathmethodandpresentssolutionsfortheeffectsofquasi-staticundrainedpenetrationofpiles.Onthebasisofclosesolutionsofthestrainrates,theclayobeysaDrucker-Prageryieldcriterion,andexhibitsDOstrainhardening
5、orsofteningduringplasticflow.Theelastic—plasticboundaryandapproximatesolutionsforpredictingtotalstresscomponentsinplasticsoilCanbeobtained.Explicitsolutionsofthetotalstressandvolumetricstressinplasticareaarecomputedbyintegratingequilibriumequationsalongspeciallines.2.Basedonthestrainpathmethod,Con
6、sideringthedistributionofthesubsidiarystressofthecompositefoundationundertheflexiblepilecapcondition,predictionofstressesandstrainsaheadofasimplerigidpileduringundrainedpenetrationinisotropicallyuncompressiblesoftclaysisattained,Thispaperalsoidentifiesimportantfactorssuchasangleoffrictionandshearm
7、oduleaffectingpenetrationstressinsurroundingsoilsofthepilelip3Withreferencetopresentexpressionofthefrictionatthepilesoilinterfaceattainedbyexperiencemethods,thispaperderivestheequilibriumconditionofthepileandther