Study On Dynamic Properties Of Anisotropic Saturated Clay

Earthquake is a kind of catastrophe. Specially, it will induce more heavy disaster in clay site because of amplification of seismic ground motion. However, there are coverd by deep and thick soft soil layers in coastal areas and inland cities in China. So, seismic site response analyses is a very important problem. But, soil behavior is complex under dynamic loading. Thus, 'How to determine stress-strain relationship' becomes the key of the problem.Firstly, based on previous researches and anisotropic clay in actual engineering, a series of undrained cyclic stress controlled triaxial tests were performed on typical Hangzhou soft clay by GDS dynamic triaxial system. The effects of initial static deviator stress, cyclic stress ratio, loading cycles, loading frequency and overconsolidation ratio on strain and pore-pressure were investigated.Secondly according to experimental data, this paper proposed a cyclic degradation model and a empirical equation of plastic strain, and determined the parameters in the models. And then, the empirical models were incorporated into Iwan's series-parallel model to account for cyclic degradation and cumulative plastic strain during cyclic loading individually. Subsequently, the dynamic stress-strain relationship of saturated soft clay is described with modified Masing's rules. As compared with experimental data and other models, the present model is proved to be reasonable and effective.Finally, in the present paper, the dynamic behavior of soil layers was described by modified Iwan's series-parallel model. And then, based on principles of one-dimensional nonlinear propagation, a program is worked out to analyze velocity(accelerogram) time history and spectra of seismic motion by an explicit technique. As compared with input data and other solutions, some useful conclusions were gotten.