Numerical modelling of liquefaction tests of partially saturated sands in CSSLB

The undrained behavior of partially saturated sands under repetitive loading has been investigated by many researchers experimentally. The research to date demonstrate that partially saturated sands do not liquefy however, significant amount of excess pore water pressures may develop especially in loose sand specimens with degrees of saturation above 80%. Cyclic Simple Shear Liquefaction Box (CSSLB) was developed by Eseller-Bayat et al. to perform cyclic simple shear tests on large specimens using a shaking table. In this study, based on the experimental results, the behavior of loose to dense partially saturated sand specimens to cyclic simple shear strains under drained and undrained conditions was modelled numerically in finite difference software program FLAC^3D (Itasca Consulting Group). The CSSLB was first modelled and the sand specimen was numerically tested under drained conditions. Then Finn and Byrne liquefaction models were used to simulate the liquefaction behavior of sands. Sand specimens with different degrees of saturation (40–83%) were tested under several cyclic simple shear strain amplitudes and the excess pore water pressures were numerically obtained. Finally, excess pore water pressure ratio (r_u) values were compared both in numerical and experimental tests. The results were also compared with the excess pore water pressures generated in fully saturated sand specimens.