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1、北京交通大學(xué)碩士學(xué)位論文降雨入滲對(duì)京九線粉土路基邊坡穩(wěn)定性的影響分析姓名:胡磊申請(qǐng)學(xué)位級(jí)別:碩士專(zhuān)業(yè):巖土工程指導(dǎo)教師:劉建坤20080601中文摘要摘要:降雨往往是誘發(fā)京九鐵路非飽和土路基邊坡失穩(wěn)的主要原因之一,這與雨后土體含水量的變化有關(guān),土體含水量的變化引起非飽和土抗剪強(qiáng)度參數(shù)的變化,從而影響土體邊坡的穩(wěn)定性。針對(duì)降雨入滲土坡的穩(wěn)定問(wèn)題,本文首先應(yīng)用Geostudi02004中的SEEP/W模塊建立了一個(gè)考慮水力滲透系數(shù)特征曲線和土一水特征曲線的非飽和土有限元計(jì)算模型,求解出不同降雨條件下的土體瞬態(tài)含水率,總結(jié)出了不同條件下的
2、降雨對(duì)土體瞬態(tài)含水率的影響規(guī)律。在此基礎(chǔ)上,應(yīng)用Geostudi02004中的SLOPE/W模塊,分別采用Bishop極限平衡法、Janbu極限平衡法、Spencer極限平衡法等計(jì)算出了不同降雨條件下非飽和土體邊坡穩(wěn)定性系數(shù)。主要結(jié)論為:在同樣的設(shè)計(jì)邊坡穩(wěn)定性系數(shù)下,降雨強(qiáng)度越大,降雨持續(xù)時(shí)間越長(zhǎng),降雨后土體邊坡穩(wěn)定性系數(shù)下降越快,邊坡越不穩(wěn)定;土體的初始含水率越高,降雨后土體邊坡穩(wěn)定性系數(shù)下降越慢;土體中邊坡安全系數(shù)與天氣條件之間存在滯后關(guān)系;降雨對(duì)邊坡的表層滑動(dòng)面穩(wěn)定性影響非常大,對(duì)深層滑動(dòng)面定性影響相對(duì)較??;降雨過(guò)程中邊坡的臨
3、界滑動(dòng)面由較深位置向較淺位置轉(zhuǎn)變。關(guān)鍵詞:非飽和土含水量安全系數(shù)基質(zhì)吸力降雨入滲分類(lèi)號(hào):ABSTRACTABSTRACT:TherainfalliSoneofthemajorfactorscausingtheunsaturatedsoilroadbedslopefailurein111eB蜘ing--KowloonRailwayLine.Thisisrelatedtothechangeofwatercontentinsoil.Ifthewatercontentischanged,theshearstrengthofthesoilbo
4、dywillbereduced,whichwillaffectthestabilit)roftheroadbedslope.Inordertosolvetheproblemofslopestabilityunderrainfallinfiltration,thispaperpresentsafiniteelementanalysismodelofunsaturatedsoilwhichconsidershydraulieconductivitycurveandsoil--watercharacteristiccurvebyusing
5、SEEP/WmoduleinGeostudio2004.Inthismodel,themainvariableismoistureratio.Themoistureratiounderdifferentrainingcondintioniscalculated.So,usingtheSLOPE/WmoduleinGeostudio2004,theslopestabilitycoefficientoftheunsaturatedsoilcanbecalculatedbasingonBishopEquilibriumbalancemet
6、hod,JanbuEquilibriumbalancemethodandSpencerEquilibriumbalancemethodetc.Themianconclusionisasfollows:whenthedesignedslopestabilitycoefficientisone,therainfallmorestrongly,theslopestabilitycoefficientdropmorequickly,therainingtimeislonger,thestabilityissmaller.Butthestab
7、ilitycoefficientfallmoreslowlywhenthefirstmoistureratioishigher.Changesinslopestabilitylagbehindthechangeofweather;Infiltrationaffectthestabilityofshallowslipsurfacegreatly,thestabilityofdeepslipsurfacerelativelylittle;Intheprocessofrain,thecriticalslipsurfacechangesfr
8、omdeepsurfacetorelativeshallowsurface.KEYWORDS:unsaturatedsoils,watercontent,slopeafety,matrixsuction,raininfiltratio