Constitutive model for effective stress based on logarithmic skeleton curve considering reversible pore pressure

The equivalent linearization method which is often used for seismic response analysis is difficult to simulate the variation of the pore pressure of saturated sandy soil, and there are few constitutive models. Almost the existing constitutive models for effective stress have not been verified by the observed records of strong motion in actual liquefiable sites. A time-domain nonlinear constitutive model for effective stress which is used in the time-domain one-dimensional nonlinear seismic response analysis of liquefiable sites with saturated sand is obtained based on the logarithmic dynamic skeleton curve, Chen long-wei's hole pressure growth model and reversible overstatic pore water pressure. The constitutive model can reasonably simulate the variation of pore pressure of saturated sand layer under the action of strong motion and the softening characteristics of soils caused by the increase of pore pressure, and is also embedded in the program Soilresp1D to realize the dynamic response analysis of liquefiable soil layer sites. It can be seen from the comparison among the simulated results of liquefiable site with saturated sand by the proposed time-domain nonlinear constitutive model for effective stress of and those by Feng Wan-ling's pore pressure growth model and the strong ground motion records of the actual liquefiable sites that the constitutive model for effective stress based on the logarithmic dynamic skeleton curve and the reversible overstatic pore water pressure is feasible, and the numerical simulated results are reasonable. In addition, by the seismic response of the site with saturated sand layers, the effects of liquefaction on the peak and the response spectra of ground acceleration and shear strength of the saturated sand layers are analyzed, and the characteristics of influence are discussed.