Abstract:

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.

Key words: unsaturated cohesive soil, triaxial compression test, stress-strain relation