工程中典型应力路径下土的应力-应变特性分析

ANALYSIS OF STRESS-STRAIN BEHAVIOR OF CLAY ALONG TYPICAL STRESS PATHS IN PRACTICAL PROJECTS

分别采用Mohr-Coulomb模型、修正剑桥模型和UH模型预测正常固结土在常规三轴压缩、三轴伸长和平均主应力p减小的压缩工况中典型路径下土的变形特性。Mohr-Coulomb模型为理想弹-塑性模型,屈服之前为弹性变形,屈服之后为变形无限增大的弹-塑性变形。修正剑桥模型能够较好地模拟压缩路径条件下正常固结土的应力-应变关系,但模型较高地估计了伸长路径条件下土的强度。UH模型为适用于正常固结土和超固结土的弹-塑性模型,其建模简单,参数与剑桥模型相同。对于正常固结土,UH模型能够退回到剑桥模型。通过采用基于SMP强度准则的变换应力方法,模型能够合理描述土的三维应力状态的特性。

The Mohr-Coulomb model, the modified Cam-clay model UH model were used to model the stress-strain relationships under the triaxial compression, extension and compression with decreasing principal stress conditions. The result predicted by the Mohr-Coulomb model, as a perfect elasto-plastic model, was elastic stress-strain relationship when stress point was in yield surface and is elasto-plastic stress-strain relationship with the constant stress and infinite increasing deformation when stress point was on yield surface under the triaxia｜ compression condition. The modified Cam-clay model could be used to predict the behavior of the normally consolidated clay in the triaxial test well, but it over-estimated the strength of clay under the extension condition. The UH model for the normally consolidated clay and over-consolidated clay had the same parameters as those in the modified Cam-clay model. For the normally consolidated clay, the UH model was the same as the modified Cam-clay model. By applying the transformed stress method based on SMP criterion, the UH model could describe the property of clay in three- dimension stress space.