基于扰动状态概念的黄土本构模型研究

发布时间：2018-02-22 21:24

  本文关键词： 黄土 扰动状态概念 本构模型 力学响应 非线性弹性扰动状态本构模型 弹塑性扰动状态本构模型 分级单屈服面模型　出处：《长安大学》2016年博士论文　论文类型：学位论文

【摘要】：对于黄土-泥岩接触面滑坡,通过有限元数值模拟对其进行变形预测的关键在于对该类滑坡发生起关键作用的土体的本构模型的选取。本文总结了国内外学者关于土本构模型和扰动状态概念的研究成果,以陕北延炼黄土-泥岩接触面滑坡滑带附近不同受力条件的Q_2和Q_1黄土为研究对象,分别进行三轴固结不排水试验和直剪试验,获得其力学参数及硬化响应和软化响应的应力应变关系,基于扰动状态概念建立了Q_2和Q_1黄土的非线性弹性本构模型和弹塑性本构模型,使用MATLAB编写了模型程序,并通过观测响应对模型进行验证、分析和评价。主要获得以下结论:(1)使用直接法和间接法建立了非线性弹性扰动状态本构模型。其中,弹性模型和非线性弹性模型用于描述无扰动状态,孔洞模型、静水应力模型、极限渐进应力模型、弹性模型和双曲非线性弹性模型用于描述完全扰动状态,共10种组合模型。对黄土软化响应的模拟结果表明:基于直接法建立的非线性弹性扰动状态本构模型可准确拟合观测响应,与参考状态模型的选取无关,但直接依赖于观测响应;基于间接法建立的模型的模拟响应与观测响应存在一定的误差,但间接依赖于观测响应,误差大小与参考状态模型的选取有关。对于Q_2黄土,无扰动状态选取非线性弹性模型,完全扰动状态选取极限渐进应力模型的组合模型模拟观测响应的效果较为理想;对于Q_1黄土,无扰动状态选取线弹性模型和非线性弹性模型,完全扰动状态选取孔洞模型、静水应力模型、极限渐进应力模型和双曲非线性弹性模型的组合模型模拟观测响应的效果较为理想。(2)建立了弹塑性扰动状态本构模型。对于Q_2和Q_1黄土的硬化响应,分别采用描述各向同性硬化和关联塑性的分级单屈服面HISS-δ_0模型和HISS-δ_0扩展模型直接定义;对于Q_2和Q_1黄土的软化响应,无扰动状态分别采用HISS-δ_0模型和HISS-δ_0扩展模型定义,完全扰动状态模型采用孔洞模型,扰动函数以塑性应变为扰动变量。对于Q_2黄土,还需分别考虑总应力路径和有效应力路径。共建立Q_2黄土总应力路径下未叠加扰动模型、Q_2黄土有效应力路径下未叠加扰动模型、Q_2黄土总应力路径下叠加扰动模型、Q_2黄土有效应力路径下叠加扰动模型、Q_1黄土未叠加扰动模型和Q_1黄土叠加扰动模型共6种弹塑性扰动状态本构模型。通过观测响应对模型程序进行验证,表明6种弹塑性扰动状态本构模型均能较好的描述Q_2和Q_1黄土的硬化响应和软化响应,体现了弹塑性扰动状态本构模型对Q_2和Q_1黄土力学响应模拟的合理性和适用性。同时,总应力路径模型较有效应力路径模型的模拟效果更合理。(3)HISS-δ_0扩展模型是由HISS-δ_0模型简化的符合Q_1黄土受力条件的二维界面模型。HISS-δ_0模型和HISS-δ_0扩展模型需要确定的参数较多,但均可通过三轴固结不排水剪切试验和固结排水直剪试验确定。HISS-δ_0模型的屈服面在I_1-J_2~(1/2)平面内呈连续光滑封闭曲线,在主应力空间呈枣核型。其主要参数硬化参数α、极限常数γ和相变常数n均可控制屈服面向外扩张的程度,极限常数γ和β可控制屈服面的破坏包线,但极限常数β无法控制屈服面的扩张。HISS-δ_0扩展模型的屈服面在τ-σ_n平面内亦为连续光滑封闭曲线,其主要硬化参数α_i、极限常数γ_i和相变常数n_i均可控制屈服面向外扩张的程度,极限常数γ_i可控制屈服面的破坏包线。(4)Q_2和Q_1黄土通过模型程序计算得到的屈服面为HISS-δ_0模型和HISS-δ_0扩展模型封闭曲面中剪切屈服面的一部分。屈服面随塑性加载不断扩张,硬化参数亦不断变化。HISS-δ_0模型屈服面受应力路径、含水率和围压的影响较大,也受模型参数g控制线型变化规律。HISS-δ_0扩展模型受含水率的影响较大。(5)经典塑性模型(Mohr-Coulomb、Drucker-Prager、von Mises、Tresca)和修正剑桥模型均为HISS模型的特殊形式。M-C模型和D-P模型的破坏包线最为接近,但均低于HISS模型的破坏包线。HISS模型与M-C模型的破坏包线在总应力路径下比有效应力路径下更接近。
[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.

【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P642.131
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本文编号：1525343