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1、分類號TU4學(xué)位論文非飽和重塑黃土變形特性試驗研究程海濤指導(dǎo)教師姓名長安大學(xué)劉保健教授申請學(xué)位級論文提交日學(xué)位授予單答辯委員會主席顧安全教授二OO五年五月摘要公路路基是公路建筑物的主體,路基沉降問題的研究從我國開始修建高等級公路就引起了重視。然而目前還沒有一種理論上可靠、實用上簡單的沉降計算方法。這將直接影響公路工程的建設(shè)與理論的發(fā)展。因此本文就非飽和重塑黃土應(yīng)力、應(yīng)變和時間三維關(guān)系及黃土流變特性等方面展開一些討論,并試圖提出一種簡單實用的填土體沉降過程計算方法。根據(jù)室內(nèi)固結(jié)試驗,本文分析了非飽和重塑黃土的割線模量,認(rèn)為應(yīng)力~應(yīng)變曲線呈良好的雙曲線關(guān)系;仿照割線模
2、量定義提出了割線應(yīng)變速率概念;從流變學(xué)角度分析了土體的變形特性;通過反復(fù)對比,認(rèn)為雙曲線與ln0It)一Int兩種曲線能較好地描述應(yīng)變隨時間的變化過程;而£一Int曲線與ln(eIt)一£曲線在應(yīng)力水平較低時呈良好的線性關(guān)系,但當(dāng)應(yīng)力水平較高時則呈明顯的非線性關(guān)系;通過參數(shù)分析與理論推導(dǎo),提出了雙曲線模型、Kelvin一雙曲線模型與ln0It)一Int模型(對數(shù)模型)。最后,應(yīng)用上述模型對蘭海高速公路路堤沉降過程進(jìn)行了計算,通過與實測沉降過程對比,證明上述模型計算土體沉降過程是可行的。關(guān)鍵詞:非飽和重塑黃土、流變特性、割線模量、沉降過程AbstractHighwa
3、ysubgradeisthemainbodyofthehighwaystructures.Thestudyofthesubgradesettlementisexcitedattentionfromthebeginningofexpresshighwayconstruction.Howeverthereisstillnoonereliableandsimplemethodtocalculatethesettlement.Thiswillinfluencethehighwayconstructionandthedevelopmentofthetheory.Asares
4、ult,thepaperwilldiscusstherelationshipamongstress,strainandtimeofunsaturatedremoldingloessandtheologicalcharacteristicofloess.Asimpleandpracticalmethodcalculatingthesettlementprocessoffluwillbeputforward.Accordingtotheconsolidationtestsindoors,thispaperanalyzesthesecantmodulusoftheuns
5、aturatedremoldingloess,thecurveofstressandstraincanbedescribedwithhyperboliccurve;thedefinitionofsecantstrainrateisputforth;thedeformationbehaviorsofsoilareanalyzedintermsofrheology;contrastingtheresultwiththetestdata,thepaperapprovesthatthehyperboliccurveandthelll(£/t)一Intcurvecandes
6、cribethedevelopmentprocessofstrainwithtime;the£一Intcarveandtheln(EIt)~£curvearelinearunderlowstressandbecomeapparentnon—linearwhenthestresslevelishigh;throughtheanalysisofthetheirparametersandtheoreticalderivation,threecomputationalmodelingsareestablished:hyperbolamathematicmodel,Kelv
7、in-hyperbolamathematicmodelandln(£It)~I(xiàn)ntmodel(109isticmodel).AtlastthesettlementprocessoftheroadembankmentofLan—Halexpresshighwayiscalculatedwiththecomputationalmodelingsgiveninthepaper.Contrastedwiththepracticalsettlementprocess,thecomputationalmodelingsarefeasibletocalculatethesett
8、lemen