發(fā)布時間：2018-02-22 21:24

  本文關鍵詞： 黃土 擾動狀態(tài)概念 本構模型 力學響應 非線性彈性擾動狀態(tài)本構模型 彈塑性擾動狀態(tài)本構模型 分級單屈服面模型　出處：《長安大學》2016年博士論文　論文類型：學位論文

【摘要】：對于黃土-泥巖接觸面滑坡,通過有限元數值模擬對其進行變形預測的關鍵在于對該類滑坡發(fā)生起關鍵作用的土體的本構模型的選取。本文總結了國內外學者關于土本構模型和擾動狀態(tài)概念的研究成果,以陜北延煉黃土-泥巖接觸面滑坡滑帶附近不同受力條件的Q_2和Q_1黃土為研究對象,分別進行三軸固結不排水試驗和直剪試驗,獲得其力學參數及硬化響應和軟化響應的應力應變關系,基于擾動狀態(tài)概念建立了Q_2和Q_1黃土的非線性彈性本構模型和彈塑性本構模型,使用MATLAB編寫了模型程序,并通過觀測響應對模型進行驗證、分析和評價。主要獲得以下結論:(1)使用直接法和間接法建立了非線性彈性擾動狀態(tài)本構模型。其中,彈性模型和非線性彈性模型用于描述無擾動狀態(tài),孔洞模型、靜水應力模型、極限漸進應力模型、彈性模型和雙曲非線性彈性模型用于描述完全擾動狀態(tài),共10種組合模型。對黃土軟化響應的模擬結果表明:基于直接法建立的非線性彈性擾動狀態(tài)本構模型可準確擬合觀測響應,與參考狀態(tài)模型的選取無關,但直接依賴于觀測響應;基于間接法建立的模型的模擬響應與觀測響應存在一定的誤差,但間接依賴于觀測響應,誤差大小與參考狀態(tài)模型的選取有關。對于Q_2黃土,無擾動狀態(tài)選取非線性彈性模型,完全擾動狀態(tài)選取極限漸進應力模型的組合模型模擬觀測響應的效果較為理想;對于Q_1黃土,無擾動狀態(tài)選取線彈性模型和非線性彈性模型,完全擾動狀態(tài)選取孔洞模型、靜水應力模型、極限漸進應力模型和雙曲非線性彈性模型的組合模型模擬觀測響應的效果較為理想。(2)建立了彈塑性擾動狀態(tài)本構模型。對于Q_2和Q_1黃土的硬化響應,分別采用描述各向同性硬化和關聯塑性的分級單屈服面HISS-δ_0模型和HISS-δ_0擴展模型直接定義;對于Q_2和Q_1黃土的軟化響應,無擾動狀態(tài)分別采用HISS-δ_0模型和HISS-δ_0擴展模型定義,完全擾動狀態(tài)模型采用孔洞模型,擾動函數以塑性應變?yōu)閿_動變量。對于Q_2黃土,還需分別考慮總應力路徑和有效應力路徑。共建立Q_2黃土總應力路徑下未疊加擾動模型、Q_2黃土有效應力路徑下未疊加擾動模型、Q_2黃土總應力路徑下疊加擾動模型、Q_2黃土有效應力路徑下疊加擾動模型、Q_1黃土未疊加擾動模型和Q_1黃土疊加擾動模型共6種彈塑性擾動狀態(tài)本構模型。通過觀測響應對模型程序進行驗證,表明6種彈塑性擾動狀態(tài)本構模型均能較好的描述Q_2和Q_1黃土的硬化響應和軟化響應,體現了彈塑性擾動狀態(tài)本構模型對Q_2和Q_1黃土力學響應模擬的合理性和適用性。同時,總應力路徑模型較有效應力路徑模型的模擬效果更合理。(3)HISS-δ_0擴展模型是由HISS-δ_0模型簡化的符合Q_1黃土受力條件的二維界面模型。HISS-δ_0模型和HISS-δ_0擴展模型需要確定的參數較多,但均可通過三軸固結不排水剪切試驗和固結排水直剪試驗確定。HISS-δ_0模型的屈服面在I_1-J_2~(1/2)平面內呈連續(xù)光滑封閉曲線,在主應力空間呈棗核型。其主要參數硬化參數α、極限常數γ和相變常數n均可控制屈服面向外擴張的程度,極限常數γ和β可控制屈服面的破壞包線,但極限常數β無法控制屈服面的擴張。HISS-δ_0擴展模型的屈服面在τ-σ_n平面內亦為連續(xù)光滑封閉曲線,其主要硬化參數α_i、極限常數γ_i和相變常數n_i均可控制屈服面向外擴張的程度,極限常數γ_i可控制屈服面的破壞包線。(4)Q_2和Q_1黃土通過模型程序計算得到的屈服面為HISS-δ_0模型和HISS-δ_0擴展模型封閉曲面中剪切屈服面的一部分。屈服面隨塑性加載不斷擴張,硬化參數亦不斷變化。HISS-δ_0模型屈服面受應力路徑、含水率和圍壓的影響較大,也受模型參數g控制線型變化規(guī)律。HISS-δ_0擴展模型受含水率的影響較大。(5)經典塑性模型(Mohr-Coulomb、Drucker-Prager、von Mises、Tresca)和修正劍橋模型均為HISS模型的特殊形式。M-C模型和D-P模型的破壞包線最為接近,但均低于HISS模型的破壞包線。HISS模型與M-C模型的破壞包線在總應力路徑下比有效應力路徑下更接近。
[Abstract]:For the Loess mudstone interface landslide, the key lies in the deformation prediction of soil plays a key role in the occurrence of landslide constitutive model is selected by finite element numerical simulation. This paper summarizes the domestic and foreign scholars on the soil constitutive model and disturbed state concept research results, in Northern Shaanxi loess mudstone contact Yanlian the surface conditions of the landslide zone near Q_2 and Q_1 loess under different as the research object, respectively, the three axis consolidated undrained test and direct shear test, the mechanical parameters and the hardening and softening response of the stress-strain relationship, based on the disturbed state concept established Q_2 and nonlinear elastic constitutive model of Q_1 loess and the elastoplastic constitutive model, using MATLAB to compile the program model, and the model is verified by observing the response, analysis and evaluation. The main conclusions are as follows: (1) the use of the direct method and indirect method construction The nonlinear elastic disturbed state constitutive model established. The elastic model and nonlinear elastic model is used to describe the non disturbance state, pore model, hydrostatic stress model, the ultimate progressive stress model, hyperbolic elastic model and nonlinear elastic model is used to describe completely the disturbed state, a total of 10 kinds of combination model. The simulation results showed the softening of loess response: direct method of nonlinear elastic disturbed state constitutive model can accurately fit the observed responses based on the selected reference model has nothing to do with the state, but in response to direct observation on response response simulation and observation; indirect method to build the model of certain error based on indirect but depends on the observation error and response. The reference state model selection. For Q_2 loess, undisturbed state selection of nonlinear elastic model, completely disturbed state selection should be gradual limit force model The model to simulate the observed response of ideal effect; for Q_1 loess, undisturbed state selection of linear elastic model and nonlinear elastic model, completely disturbed state selected hole model, hydrostatic stress model, the limit should be gradual combination model of force model and the hyperbolic nonlinear elastic model to simulate the observed response of the ideal effect (2) was established. Elastoplastic disturbed state constitutive model for hardening Q_2 and Q_1 loess response, were used to describe the isotropic hardening and the associated plastic hiss HISS- Delta HISS- Delta _0 model and extended _0 model direct definition; Q_2 and Q_1 for softening response of loess, undisturbed state respectively by HISS- Delta _0 model HISS- and delta _0 extended model definitions, completely disturbed state model by the hole model, the perturbation function with plastic strain as disturbance variables. For Q_2 loess, also need to separately consider the total stress path and effective Stress path. Build Q_2 loess should always be disturbance model is not superimposed stress path, the effective disturbance model of Q_2 loess is not superimposed stress path, Q_2 loess total stress path superposition disturbance model, loess Q_2 effective stress path under superimposed disturbance model, Q_1 model and non disturbance superposition Loess loess Q_1 superimposed disturbance the model consists of 6 types of elastoplastic disturbed state constitutive model. By observing the response of the model validation procedures, showed that 6 kinds of hardening elasto-plastic disturbance description Q_2 and Q_1 loess state constitutive model can better response and softening response, reflecting the elastoplastic disturbed state constitutive model response simulation rationality and the applicability of Q_2 and Q_1 in Loess Mechanics. At the same time, the total stress path model is effective to simulate the effect of stress path model is more reasonable. (3) HISS- _0 model is simplified by delta HISS- Delta _0 model with Q_1 loess stress condition of the two dimension Many parameters need to be determined in the extended model _0 model and interface model.HISS- Delta HISS- Delta _0, but can be through the three axis consolidated undrained shear test and consolidated drained direct shear test yield surface.HISS- Delta _0 model identified in I_1-J_2~ (1/2) in the plane of a continuous smooth closed curve in the principal stress space was date karyotype. The main parameters of hardening parameters, limit constant gamma and constant n control for phase change can yield expansion degree, limit constant gamma and beta can control the yield surface failure envelope, but the limit constant cannot control the yield surface expansion of.HISS- delta extended _0 model yield surface in tau Sigma _n plane is also continuous and smooth a closed curve, the hardening parameter alpha _i, constant _i and constant phase limit n_i can control the yield oriented expansion degree, constant _i control limit yield surface failure envelope. (4) Q_2 and Q_1 loess through the model program The calculated yield surface model in a part of a closed surface shear yield surface for _0 model and HISS- HISS- Delta Delta _0. The yield surface with plastic loading expansion, hardening parameters have been changed.HISS- Delta _0 model yield surface stress path, influence of water content and confining pressure is bigger, but also by the model parameters G control of linear variation of.HISS- Delta _0 larger extension model is affected by water content. (5) classical plasticity models (Mohr-Coulomb, Drucker-Prager, von, Mises, Tresca) broken wire and modified Cambridge model are the special form of HISS model.M-C model and D-P model is the most close, but lower than that of HISS model failure envelope of.HISS model and M-C model of the failure envelope in the total stress path than the effective stress path under the closer.

【學位授予單位】：長安大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：P642.131
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本文編號：1525343