Investigation of the influence of permeability coefficient on the numerical modeling of the liquefaction phenomenon

The soil permeability coefficient plays a key role in the process of numerical simulation of the liquefaction phenomenon. Liquefaction causes a considerable increase in soil permeability, due to the creation of easier paths for water flow. The work presented in this paper tries to investigate the effects of permeability coefficient on the results of numerical modeling of the liquefaction phenomenon. To do this, a fully coupled (u-P) formulation is employed to analyze soil displacements and pore water pressures. Two different versions of a well-calibrated critical state bounding surface plasticity model, which possesses the capability to utilize a single set of material parameters for a wide range of void ratios and initial stress states for the same soil, are used to model the behavior of saturated sand. To demonstrate the accuracy of the numerical model, two different finite element programs, which apply different numerical algorithms, are employed and validated by records of a centrifuge test. The obtained results indicate that by considering a constant value for the soil permeability coefficient, pore pressure variations and soil displacements cannot be simulated simultaneously. Therefore, variation of the permeability coefficient should necessarily be taken into account in the course of numerical analysis of liquefaction in order to achieve acceptable prediction of both pore pressures and displacements.