上海结构性软黏土本构模型与试验验证

天然上海软黏土具有很强的结构性,传统的剑桥模型无法合理地对其进行描述,改进后的运动硬化结构模型不仅引入了描述土体结构性的状态变量,可以反映土体塑性应变发展过程中所产生的结构损伤对其力学行为的影响,还对原始运动硬化结构模型中的形状参数、塑性模量公式等进行了改进,能更好地描述上海软黏土的力学行为。基于改进之后的运动硬化结构模型,通过天然上海软黏土等压固结三轴不排水剪切试验对该模型进行参数标定,进而对偏压固结三轴不排水剪切试验与加-卸载等向压缩试验进行预测。结果表明:改进后的运动硬化结构模型可以更好地模拟上海软黏土在三轴试验中的结构损伤、应力路径以及应力应变关系,同时对加-卸载过程中土体的滞回特性也有较好的模拟效果。

Constitutive Model and Experimental Verification of Shanghai Structured Soft Clay

The natural Shanghai soft clay has a strong structure, which cannot be reasonably described by the traditional Cam-clay model. The modified kinematic hardening structure model introduces the state variables to describe the structure of soil, which can reflect the influence of structure degradation on the mechanical behavior of soil during the development of plastic strain. Furthermore, the shape parameter and plastic modulus formula of the original model are improved, which can better describe the mechanical behavior of Shanghai soft clay. Based on the modified kinematic hardening structure model, the model parameters are calibrated by isotropic consolidation undrained triaxial tests of natural Shanghai soft clay, and then be used for predicting the soil behavior under anisotropic consolidation undrained triaxial tests and loading-unloading isotropic compression tests. The results show that the modified kinematic hardening structure model can better simulate the structure degradation, stress path and stress-strain behavior of Shanghai soft clay in triaxial tests. It also has a good simulation effect on the hysteretic characteristics of soil in the process of loading-unloading.