将非饱和土广义有效应力变量法应用于三剪强度准则,得到非饱和土广义有效应力三剪强度准则。在该准则基础上推导出广义有效变量法下的三剪破坏应力比和新的屈服面方程。引入S-R分解法理论,在有限变形弹塑性理论的框架下,建立了适用于正常固结非饱和黏性土的三剪有限变形弹塑性本构模型。所建本构模型与非饱和土常规三轴试验对比结果表明,有限变形本构模型模拟结果与试验点吻合较好,验证了该本构模型对岩土材料进行有限变形弹塑性分析的可行性。所建本构模型与小变形本构模型对比结果表明,在初始压实度、净围压、基质吸力都相同的情况下,所建本构模型计算结果比小变形本构模型计算结果更加精确。真三轴固结排水试验数值模拟结果表明,其他条件相同的条件下,土体偏应力和体积变形量与中间主应力影响系数呈正相关。
The generalized effective stress variable method for unsaturated soils was applied to the triple-shear strength criterion to obtain the generalized effective stress triple-shear strength criterion for unsaturated soils. Based on this criterion, the three-shear destructive stress ratio and the new yield surface equation under the generalized effective variable method were derived. Subsequently, by introducing the S-R decomposition theorem within the framework of finite deformation elastoplastic theory, a three-shear finite deformation elastoplastic constitutive model suitable for normally consolidated unsaturated cohesive soils was established. Comparison between the established constitutive model and the conventional triaxial test of unsaturated soil shows that the simulation results of the finite deformation constitutive model are in good agreement with the test points, which verifies the feasibility of this constitutive model for finite deformation elastoplastic analysis of geotechnical materials. Comparison between the established constitutive model and the infinitesimal strain constitutive model shows that the calculation results of the established constitutive model are more accurate than the calculation results of the infinitesimal strain constitutive model under the same conditions of initial compaction, net confining pressure and matrix suction. The numerical simulation results of the true triaxial consolidation and drainage test show that, all other conditions being equal, the deviatoric stress and volumetric deformation of the soil body is positively correlated with the influence coefficient of the intermediate principal stress.
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