The Experimental Study On The Mechanical Characteristics Of Expansive Soil Considering The Stress History

The strength of the expansive soil will be affected by the change of its constraint conditions after excavation or disturbance. In practical engineering, due to the changes in initial stress field, the rebound deformation will occurs after the expansive soil surface excavated to slope. The conventional limit equilibrium stability analysis which doesn’t take the elastic deformation of expansive soil in, will also not take the reduction of the strength parameters in consideration. Ignoring that the soil is the typical stress path dependence of material properties, the stress history and stress path of the soil has great influence in characteristics of stress-strain. The excavation and unloading stress path is a kind of loading mode different from the the conventional loading,so take it distinct The soil samples with typical expansive properties in Hefei was selected to take the geotechnical tests in laboratory, and the liquid limit, plastic limit, free expansion rate, preconsolidation stress and a series of indicators was got to make the initial judgment of expansive soil. he effect of stress history on the mechanical characteristics of swelling soil was explored by the different consolidation ratio of direct shear test and conventional three axis test. The results show that the shear strength is higher relative as the overconsolidation ratio of soil:the influence of stress path on the mechanical characteristics of swelling soil was explored by the test of three conventional triaxial test and unloading path, and the results show that the shear strength of expansive soil will have a certain degree of attenuationunder the unloading path. Through the analysis of the qualitative test, the conclusion is that expansive soil strength parameters and stress history&stress path is relevance. Finally, by using the tests datas and access to relevant information, the parameters of the Deng Kenzhang model was get. The conventional triaxial test and the unloading triaxial test were simulated and analyzed by using the finite element software ABAQUS.