UNDRAINED CYCLIC ACCUMULATIVE DEFORMATION OF SATURATED SOFT CLAY CONSIDERING INFLUENCE OF DEVIATION ANGLE OF PRINCIPAL STRESS AXIS
(1. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China；2. School of Civil Engineering and Architecture，Anhui University of Science and Technology，Huainan，Anhui 232001，China；3. Key Laboratory of Geotechnical
and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China)
Abstract：The traditional model based on triaxial cyclic loading test could not reflect the phenomenon of initial principal stress axis deviation of soil element under gravity stress. The cyclic loading test data for building the constitutive model considering the influence of deviation angle of principal stress axis can be obtained by the dynamic hollow cylinder shear test. The equipment for making the soft clay hollow cylindrical sample is manufactured according to the physico-mechanical properties of the 4th layer of saturated soft clay in Shanghai. Under the constant deviation angle of principal stress axis，the cyclic loading waveform equation and the total stress loading equation which could control the static shear test are deduced. The undrained shear tests and dynamic tests of the 4th layer of saturated soft clay in Shanghai are carried out under different constant deviation angles of principal stress axis. After discussing the rules that the deviation angle of principal stress axis affects the cyclic accumulative strain and the undrained shear strength，the explicit model is put forward which could reflect the deviation angle of principal stress axis. The model parameters are of physical significance and are easy to be obtained. The explicit model is validated based on undrained cyclic test data. It will be more effective to calculate the long-term settlement of subgrade under traffic loading with the proposed explicit model.
2011, Vol. 30 
