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1、湖南大學(xué)碩士學(xué)位論文基樁豎向變形與承載力機(jī)理研究姓名:何俊翹申請(qǐng)學(xué)位級(jí)別:碩士專業(yè):巖土工程指導(dǎo)教師:趙明華2002.4.8塑塑盔堂堡主堂垡堡墨一——基樁豎向變形與承載力機(jī)理研究(摘要)研究生:指導(dǎo)教師:何俊翹趙明華教授豎向荷載下基樁的承載機(jī)理及沉降分析國(guó)內(nèi)外已有大量研究,工程中多以承載力作為基樁的設(shè)計(jì)控制指標(biāo)。然而,對(duì)于那些對(duì)沉降極為敏感的超靜定結(jié)構(gòu),往往需要對(duì)樁頂沉降進(jìn)行控制。1本文結(jié)合湖南省交通廳“茅草街大橋主墩樁基礎(chǔ)按樁頂變形控制基樁承載力研究”課題,通過深入分析豎向荷載作用下基樁的荷載傳遞過程、變化規(guī)律和荷載一沉降特性等機(jī)理,提出了~種新
2、的基樁荷載傳遞模型,對(duì)樁側(cè)摩阻力的計(jì)算采用隨土體變形變化的三折線模型,對(duì)樁端土抗力的計(jì)算采用雙折線模型。其綜合考慮了樁側(cè)摩阻力的深度效應(yīng)、不同樁側(cè)土類的影響,以及樁端阻力的非線性特性等,可較全面地模擬樁一土相互作用的實(shí)際情況,并適用于不同的成樁工藝。以改進(jìn)模型為基礎(chǔ),分別考慮樁頂沉降處于彈性、彈塑性或塑性等狀態(tài),導(dǎo)得了以樁頂沉降量控制基樁豎向承載力的一系列公式,其計(jì)算簡(jiǎn)單,應(yīng)用方便。并就本文提出的計(jì)算模型和分析方法開發(fā)出相應(yīng)的計(jì)算程序,可用于指導(dǎo)工程實(shí)踐。此外,本文還完成了茅草街大橋大型基樁靜載荷試驗(yàn),得到了一系列有益的成果。最后,以基于改進(jìn)模型的
3、計(jì)算結(jié)果與現(xiàn)場(chǎng)靜載荷試驗(yàn)結(jié)果進(jìn)行了對(duì)比分析,其結(jié)果基本吻合。關(guān)鍵詞:基樁承載力、荷載傳遞模型、沉降計(jì)算、靜載荷試驗(yàn)塑墮奎堂墮主蘭垡笙奎——StudyontheBehaviorofDeformationandBearingCapacityofVerticallyLoadedPiles(ABSTRACT)HeJunqiaoSupervisedbyProf.ZhaoMinghuaRecently,substantiveresearcheshavebeendoneonthebearingmechanismandsettlementanalysisofpil
4、esunderverticallyloads.Whilebearingcapacityisusuallythedominatingparameterindesign,thetopsettlementofpiles,especiallythoseinstaticallyindeterminatestructuresthataresensitivetosettlement,alsoneedstobecontrolled.Combinedwiththescientificresearchtask‘‘ResearchonControllingtheBear
5、ingCapacitybyVirtueoftheTopSettlementofPileFoundationofMaocaojieBriage”financedbytheCommunicationDepartmentofHunanProvince,adetailedanalysisoftheloadtransfermechanismofverticallyloadedpileshasbeenmadeandanewloadtransfermodelisproposedinthispaper.Thedeptheffectoftheshaftresista
6、nce,theinfluenceofdissimilarsoiltypes,aswellasthenonlinearresponseofthebaseresistance,areconsideredinthismodel,whichcancomprehensivelysimulatetheactualityofthepile—soilinteractionandbeapplicabletodifferentconstructionmethods.Basedontheimprovedmodelandrespectivelyconsideringthe
7、topsettlementinelastic,elastic-plasticorplasticstatus,aseriesofformulaswerededucedforhowtocontroltheverticalbearingcapacityofpilesbymeansofthetopsettlementvalues.Correspondingexploitedcomputingprocedure,isintroducedinthispaperaswell.Besides,theinstrumentedpiletestofMaocaojieBr
8、idgewasaccomplishedandasetofrewardingresultswasobtained.Atlas