Dynamics of nonlinear porous media with applications to soil liquefaction

This paper provides a description of the extension of Biot's theory for dynamic behavior of saturated porous media into the nonlinear regime that was introduced by the second author in 1980. It also provides a finite element implementation of this extension and two numerical applications involving the seismic behavior of saturated soil deposits. In the first numerical application, the dynamic interaction between liquefying soil and a structure sitting on the ground surface is examined, with emphasis on the interplay between the seismic loading rate and the (evolving) characteristic frequency of the soil-structure system. The attenuation of seismic energy as the seismic waves pass through softened soil is also discussed. The second numerical application involves the seismically induced liquefaction of stochastically spatially variable soils. It is explained why more pore-water pressure is generated in a heterogeneous soil than in a corresponding uniform soil. Comparisons are also provided with experimental centrifuge data.