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1、中國科學(xué)院武漢巖土力學(xué)研究所碩士學(xué)位論文柔性基礎(chǔ)下剛性樁復(fù)合地基樁土應(yīng)力分布研究姓名:姜志全申請學(xué)位級別:碩士專業(yè):巖土工程指導(dǎo)教師:李廷芥;倪光樂20040601論文摘要在道路工程中,經(jīng)常采用CFG樁、素砼樁等剛性樁復(fù)合地基處理軟土路基。在取得良好處理效果的同時,也出現(xiàn)了如沉降過大、沉降差過大甚至路基失穩(wěn)等工程問題。本文從彈性理論中點荷裁的Bous§inesq解和Minfilin解出發(fā),得到各種荷載分布形式下的Boussinesq解和Mindlin解,從而推導(dǎo)出地面荷載、樁頂荷載、樁側(cè)摩阻力和樁端阻力在
2、復(fù)合地基內(nèi)任一點打生的附加應(yīng)力和沉降。本文將復(fù)合地基劃分為若干復(fù)合單元,每個復(fù)合單元包括若于樁身單元和二t單元。樁身單元和土單元存在著相互作用,在允許樁土相對滑移的前提下,建立樁頂土體沉降與樁頂沉降的協(xié)調(diào)方程、樁底二}二體沉降與樁端沉降的協(xié)調(diào)方程、樁土相對位移與樁側(cè)摩阻力的物理方程、樁身力的平衡方程、樁身壓縮和樁頂沉降與樁端沉降之差的協(xié)調(diào)方程。根據(jù)這些融調(diào)方程組,在給定一組初始樁側(cè)摩阻力系數(shù)的條件下,運用迭代計算,最終可求出復(fù)合地基中的樁頂荷載、樁側(cè)摩阻力、樁頂沉降及樁問土的受力和沉降。利用本計算模型對某
3、橋頭引道復(fù)合地基進(jìn)行了計算分析.計算值與實測值吻合良好。通過選取某一路基斷面,利用本計算模型對柔性基jifl{下復(fù)合地基樁土應(yīng)力分柑狀態(tài)進(jìn)行了計算分析,揭示了柔性基礎(chǔ)下剛性挫復(fù)合地基搬:土應(yīng)力分西-規(guī)律。計算結(jié)果和實{91
4、j結(jié)果的一致性流明利用本模型分析復(fù)合地基中應(yīng)力分布理論上是可行的,計算精度是可信的。關(guān)鍵詞:復(fù)合地基Boussinesq解Mindlin解沉降應(yīng)力分粕AbstractCompositefoundationsuchasCFGpile,concretepilecompositefounda
5、tionetc.isoftenusedtoimprovesubgradebearingcapacityinroadengineering.Becauseofinadequateanalysisinconsolidationmechanismofcompositefoundation,aseriesofengineeringproblemssuchasexcessivesettlementandseRlementdifferenceofsubgrade,roadbedslidingfailurearebro
6、ughtout.Inthisthesis,additioralstressandsettlementincompositefoundation,whicharecausedbyloads,loadsonthepilecap,sidefrictionalstressandrestraintsofpilehead,aredevelopedbasedonBoussinesqfommlasandMindlinformulas.Inthisthesis,thecompositefoundationisdivided
7、intoacertaincompositecells.Eachcompositecellincludesacertainpileshaftcellsandsoilcell.Undertheconditionoftheslidebetweenpileandsoilaroundpileistakedintoaccount,fiveequationsareestablished,includingtheequationofcompatibilitybetweenthesettlementofpilecapsoi
8、landthesettlementofpilecap;theequationofcompatibilitybetweentheseRlementofpileheadsoilandthesettlementofpilehead;thephysicalequationbetweenthesettlementofsoilaroundpileshaftandthesettlementofpileshaft;theequationofequilibriumbetweenloadsonthepilecap,sidef
9、rictionalstressandrestraintsofpilehead;theequationofcompatibilitybetweenthedeformationofthepilebodyandthesubtractionbetweenthesettlementofpilecapandthesettlementofpileheap.Withiterativecalculationmethod,loadsofpilec