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1、華中科技大學(xué)碩士學(xué)位論文雙向增強體復(fù)合地基的樁土應(yīng)力比研究姓名:王熹申請學(xué)位級別:碩士專業(yè):巖土工程指導(dǎo)教師:鄭俊杰20070601摘要復(fù)合地基法近幾十年來在國內(nèi)外得到了廣泛應(yīng)用,近年來雙向增強體復(fù)合地基法在地基處理中應(yīng)用較多,但對其作用機理及設(shè)計理論的研究還較少。本文對雙向增強體復(fù)合地基(以樁承式格柵加筋路堤為主)的樁土應(yīng)力比進(jìn)行了研究。首先,對樁承式格柵加筋復(fù)合地基的網(wǎng)材受力情況作了研究。選取相鄰四根樁之間的網(wǎng)材為研究對象,分析了網(wǎng)材的受力組成并進(jìn)行求解,得到了網(wǎng)材受力的解析計算式。分析了各參數(shù)對網(wǎng)材受力的影響,得到了一些變化規(guī)律。認(rèn)為網(wǎng)材拉應(yīng)力隨格柵抗拉強度E、
2、最大沉降S、路堤土重度γ以及路堤土換算高度H的增加而增加,gm隨樁間距l(xiāng)的增加而減小。并在最后提出了修正及建議。接著,對樁土應(yīng)力比作了研究。選取單樁影響范圍的復(fù)合土體為研究對象,假定樁間土上部水平加筋材料受上覆土壓力作用后變形為二次拋物面,考慮水平加筋材料對樁頂?shù)淖饔昧?,通過建立整體平衡方程,推導(dǎo)出了加筋路堤下樁式復(fù)合地基的樁土應(yīng)力比的解析表達(dá)式。分析了各參數(shù)對樁土應(yīng)力比的影響,樁土應(yīng)力比n隨著樁間距l(xiāng)、最大沉降量S、路堤土換算高度H以及路堤土重度γ的增大而增大,隨樁半徑r、m樁間土應(yīng)力發(fā)揮系數(shù)λ、地基土承載力標(biāo)準(zhǔn)值f的增大而減小。sk最后,通過既有工程實例的實測數(shù)據(jù)
3、,對推導(dǎo)出來的樁土應(yīng)力比計算公式進(jìn)行驗證,并得到了計算公式中修正系數(shù)α在疏樁和密樁兩種情況下的取值范圍。本文的成果可為雙向增強體復(fù)合地基的理論研究及工程應(yīng)用提供有價值的參考。關(guān)鍵詞:雙向復(fù)合地基土工格柵樁土應(yīng)力比加筋墊層路堤IAbstractThecompositefoundationmethodhasbeenextensivelyusedathomeandabroadinthepastdecades.Thebi-axiallyreinforcedcompositefoundationmethodhasbeenmoreappliedingroundtreatment,
4、butthemechanismanddesigntheoryhasseldomstudied.Thisthesisdealswiththepile-soilstressratioofbi-axiallyreinforcedcompositefoundation(pile-supportedgeosynthetics-reinfoecedembankment).Firstly,thestressesofgeogridinpile-supportedgeogrid-reinforcedcompositefoundationwereanalyzed.Thegeogridco
5、veringfourpileswastakenasasimplemodel,theconstituentofstresseswasdiscussedandtheanalyticsolutionofgeogridstresswasobtained.Theinfluenceofallparametersongeogridstresseswasinvestigated.Thefollowingconclusionsweredrawn:thestressesofgeogridincreasewhenthevaluesoftensilestrengthofgeogridE,th
6、emaximumsettlementS,unitweightofembankmentgmsoilγ,theequaliventheightofembankmentHincrease,decreasewhenthepilespacinglincreases,andsomesuggestionsweremade.Secondly,thepile-soilstressratiohadbeenstudied.Thecompositesoilmasswithintheinfluencescopeofsinglepilewastakenasasimplemodel,andthea
7、ssumptionthatthegeosyntheticsabovethesoilbetweenpilesdeformedasaparaboloidaftertheloadingoftheoverlyingsoilwasmade.Aftertakingtheactionofthegeosyntheticstothepiletopintoaccount,byestablishingtheglobalequilibriumequation,theanalyticsolutionofthepile-soilstressratioofpile-support