Abstract: In order to study the mechanical behavior of soil-structure interface under the constant stress increment ratio stress paths

the simple shear tests of interface between high plasticity clay and concrete face were carried out

from the tests

the stress-strain relation curves under different stress paths were obtained. Five main phenomena were found

firstly

the high plasticity clay could well suitable to large deformation

and had strain-hardening behavior obviously

as well as

the little dilatancy; secondly

there was no correlation between stress paths and shear strength but the stress-strain relations were influenced by stress paths; thirdly

the little stress increment ratio

the higher increase speeding of shear stress and breaking strength under the condition of same initial normal stress; the fourth

the relations between normal strain and normal stress in simple shear test was consistent with which in the single-direction compression test

if there was no dilatancy; the last

the curve of relation between stress ratio and shear strain could be well simulated by hyperbola. Based on the test result and generalized potential theory

a bi-potential surface elasto-plastic model for soil-structure interface was created

in which the soil-structure interface problem was regard as a two-dimensional mathematical question in stress field

and plastic state equations were used to replace the traditional field surface. Studying shown that the proposed model which could reflect the infection of stress paths and initial normal stress on mechanical behavior of interface had a universal character and could be used in FEM

so it was good to be promoted and applied in the interface studying field.