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1、...頁眉鄧肯模型參數(shù)k、n、Rf整理方法研究張波(西安地質(zhì)礦產(chǎn)勘查開發(fā)院,陜西,西安710100.)摘要:對四種石渣料進行三軸CD試驗,采用全部法(全部試驗點)、70~95法(應力水平70~95%的試驗點)及分段法(小應變試驗點求參數(shù)k、n,應力水平70~95%的試驗點求參數(shù)Rf)三種方法來求取Duncan-Chang模型參數(shù)k、n、Rf,并采用三種方法求取的參數(shù)擬合應變應變曲線與試驗曲線對比,研究了不同求取方法的優(yōu)劣。結(jié)果表明:三軸試驗應力應變曲線并不完全符合雙曲線關(guān)系,ε1/(σ1-σ3)~ε1關(guān)系曲線
2、表現(xiàn)出明顯的雙線性,轉(zhuǎn)折點應變約為1%;石渣料雖然是無粘性土,但其粘聚力并不為零,在工程中應予適當考慮;全部法和70~95法求取的參數(shù)擬合曲線與試驗曲線較為吻合,擬合效果較好,但考慮到應力應變軟化問題,70~95法求取的參數(shù)能較好的模擬試驗曲線,分段法求取的參數(shù)雖然符合物理力學意義,但由于求取參數(shù)k、n僅采用小應變的試驗點,擬合曲線與試驗曲線差別較大,建議采用應力水平70~95%的試驗點求取Duncan-Chang模型參數(shù)k、n、Rf。關(guān)鍵詞:三軸試驗;石渣料;Duncan-Chang模型;應力-應變Dunc
3、anmodelparametersk,n,Rfsortingmethod/ZhangBo,(Xi’anInstituteofGeologicalAndMineralexploration,Xi’anShannxi710100,China)Abstract:ThefourkindsofgravelmaterialfortriaxialCDtests,usingallmethods(alltestpoints),70-95method(stresslevel70~95%oftestpoints)andsectio
4、nmethod(smallstraintestpointdemandparameterk,n,thestresslevelof70to95%ofthetestpointsrequestparameterRf)arethreewaystostrikeaDuncan-Changmodelparametersk,n,Rf,andtheuseofthreemethodsofparameterfittingtostrikeastrain-straincurvesandtestcurvescomparativestudy
5、oftheprosandconsofdifferentmethodstostrike.Theresultsshowedthat:Triaxialstress-straincurvedoesnotfullycomplywiththehyperbolicrelationship,ε1/(σ1-σ3)~ε1curveshowedaclearbilinear,theturningpointisabout1%strain;carbidematerialalthoughnoviscoussoil,butitscohesi
6、onisnotzero,theprojectshouldbeproperlytakenintoaccount;alllawandtostrikethelawfrom70to95parameterfittingcurveismoreconsistentwiththeexperimentalcurve,fitbetter,butconsideringthestressstrain-softeningproblems,70to95lawparameterscanstrikeabettersimulationcurv
7、e,althoughtheparametersofsub-strikelawinlinewiththephysicalandmechanicalsense,buttostrikeaparameterk,nusingonlyasmallstrainoftestpoints,theproposedcurvetogetherwiththeexperimentalcurvesvarygreatly,thestresslevelisrecommended70to95%ofthetestpointstostrikeDun
8、can-Changmodelparametersk,n,Rf.Keywords:triaxialtests;carbidematerial;Duncan-Changmodel;stress-strain1引言土的本構(gòu)模型研究是目前巖土工程的重要課題之一,目前主要有非線性彈性模型及彈塑性模型[1]。前者中的Duncan-Chang模型[2]是基于Kondner[3]應力應變符合雙曲線的假定下建立的,以