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1、分類號密級變截面與等截面管樁復(fù)合地基承載特性對比研究研究生姓名:黃禮勝指導(dǎo)教師姓名、職稱:劉杰教授學(xué)科專業(yè):巖土工程研究方向:地基處理湖南工業(yè)大學(xué)二〇一四年六月八日萬方數(shù)據(jù)萬方數(shù)據(jù)萬方數(shù)據(jù)摘要本文依托國家自然科學(xué)基金資助的“階梯型混凝土預(yù)制管樁單樁承載性能及接管關(guān)鍵技術(shù)研究”項目,在較系統(tǒng)地分析傳統(tǒng)等截面管樁復(fù)合地基在實踐中所存在的不足的基礎(chǔ)上,通過室內(nèi)模型試驗及數(shù)值的模擬等手段,對比研究了階梯形變截面管樁與等截面管樁復(fù)合地基的工作性狀,總結(jié)了階梯形變截面管樁復(fù)合地基的優(yōu)點。主要研究內(nèi)容如下。(1)基于室內(nèi)復(fù)合地基大比例模型靜載試驗,對比
2、研究了階梯形變截面管樁與等截面管樁復(fù)合地基的工作性狀。獲得了如下結(jié)論:階梯形變截面管樁單樁剛度明顯要大于等截面管樁的單樁剛度;階梯形變截面管樁復(fù)合地基中的樁-土應(yīng)力比及樁側(cè)摩阻力要高于等截面管樁復(fù)合地基中的樁-土應(yīng)力比及樁側(cè)摩阻力;在相同荷載作用下,階梯形變截面管樁復(fù)合地基的沉降及樁端反力明顯低于等截面管樁復(fù)合地基的沉降及樁端反力。因此,采用階梯形變截面管樁復(fù)合地基技術(shù),對充分利用淺層土的承載能力來改善單樁的荷載傳遞性狀,提高復(fù)合地基的承載能力,降低地基沉降具有很好的效果。(2)基于FLAC3D建立了階梯形截面管樁復(fù)合地基數(shù)值模擬模型,室
3、內(nèi)復(fù)合地基大比例模型靜載試驗結(jié)果驗證了數(shù)值模擬模型的正確性與合理性,為階梯形變截面管樁復(fù)合地基承載及沉降性狀的全面分析奠定了理論基礎(chǔ)。關(guān)鍵詞:階梯形變截面管樁,復(fù)合地基,荷載–沉降,樁土應(yīng)力比,樁身荷載傳遞規(guī)律I萬方數(shù)據(jù)ABSTRACTThethesisissupportedby“Studyonsinglepilebearingcapabilityandconnectionkeytechnologyofstepssectionconcreteprecastpipepile”program,whichisfoundedbyNationalN
4、aturalScienceFounding.Thedeficienciesinthepracticehavebeendiscoveredbysystematicalanalysisoncompositefoundationoftraditionaluniformsectionpipepile.Workpropertiesofladder-shapedvariablecross-sectionanduniformsectionpipepileincompositefoundationhavebeencontraststudybyindoor
5、modeltestandnumericalsimulation.Theadvantagesoftheladder-shapedvariablecross-sectionpipepileincompositefoundationissummarized.Themainresearchcontenthasbeendrawnasfollows.(1)Onthebasisofindoorlargescalemodelstaticloadtestoncompositefoundation,workpropertiesofladder-shapedv
6、ariablecross-sectionanduniformsectionpipepileincompositefoundationhavebeencontraststudy.Conclusionshavebeendrawasfollows:thestiffnessofladder-shapedvariablecross-sectionsinglepileissignificantlygreaterthanthatofuniformsectionsinglepile;thepile-soilstressratioandpilesidefr
7、ictionofladder-shapedvariablecross-sectionpipepileincompositefoundationisgreaterthanthatofuniformsectionpipepileincompositefoundation;undersameloading,thesedimentationandthepileendresistanceofladder-shapedvariablecross-sectionpipepileincompositefoundationisobviouslylessth
8、anthatofuniformsectionpipepileincompositefoundation.Therefore,compositefoundationtechnologyoflad