非饱和黏性土的应力-应变关系研究

为了绕过吸力这一复杂的变量建立尽量简便实用的非饱和土本构模型,在双曲线模型的基础上将含水率引入硬化参数中.提出在试验前让土样恢复到原始应力状态下的理论,并依据该理论对三轴试验方法进行改进.为了很好的研究各个含水率下原状土的应力-应变关系,利用重塑土实现原状土的模拟.试验结果表明:重塑非饱和黏性土的应力-应变关系基本符合Kondner提出的双曲线模型.在研究双曲线模型中的参数a和b的规律性的基础上,建立了100、150、200与250 kPa 4种围压状态下参数a和b与含水率的函数关系,并实现了对补做的一组含水率为24.52 %的应力-应变关系的预测.通过实测数据与预测结果对比,发现预测误差比较小,能达到较好的预测效果.

Research on stress-strain relation of unsaturated cohesive soil

Based on a hyperbolic model of soil, water content instead of matrix suction is introduced into the hardening parameter of the model to develop a constitutive model on unsaturated soil as simple and feasible as possible. A theory which the disturbed soil sample renews primary stress state before test is put forward, and the test method is improved by it. In order to study stress-strain relation for different water contents, the test simulates undisturbed soil with remolded soil. The test result shows that stress-strain relation of remolded unsaturated cohesive soil essentially accords with hyperbolic model which Kondner put forward. On the basis of studying rule for parameters a and b in the hyperbolic model, functions between parameters a and b and the water contents under confining pressures of 100, 150, 200 and 250 kPa are established. And then the stress-strain relation which the water content is 24.52 % is predicted. The contrast between testing data and predicted results shows that predicted error is relative small, and the results satisfy the demand of expectation.