By test of swelling pressure and expansion rate with cutting ring sample under different restrained pressures

it is shown that the restrained pressure has obvious influence on expansive soil’s expansibility; the greater restrained pressure is

the smaller expansibility is. On this basis

experiments in three kinds of different restrained conditions of expansive soil are designed:(1) the lateral

upside and downside of the expansive soil are restrained.(2) the lateral and downside of the soil are restrained

while the upside is unrestrained.(3) the lateral of the soil is restrained

upside and downside unrestrained. The test results indicate that different restrained conditions have obvious influence on expansive soil’s physical and mechanical characteristics such as moisture content

density

void ratio and shear strength. Furthermore

expansive soil is more easily deformed along unrestrained surface. Furthermore

when the upside and downside of expansive soil are unrestrained

the expansive soil’s moisture content is close to its liquid limit after sopping water. The study will provide important basis for the control of the expansive soil.