In order to study the real strength characteristics of expansive soil,the low stress shear strength of remolded expansive soils under the constant amplitude dry wet cycle cyclic conditions was tested by using the conventional direct shear test.The change relationship between the low stress shear strength parameters of the remolded expansive soils,the number of cycles and the amplitude of the cycle were studied.The nonlinear function of the cohesion with the variables that contains the initial moisture content,cycle amplitude and number of cycles was established.The test results showed that under the same cycle amplitude and initial control water rate condition,the cohesion of expansive soil decayed with the increase of the number of cycles.Under the same cycle number and the initial control water rate,the cohesion of expansive soil decayed with the increase of the amplitude of the cycle.The relationship between the internal friction angle,the amplitude of cycles and the cycle times could not be expressed by a function.The nonlinear cohesive strength attenuation function was obtained by simple laboratory test,which can be used to calculate the cohesion of expansive soil under the condition of amplitude dry wet circulation.
