A numerical study of the effect of boundary conditions on liquefaction

Abstract

Cyclic triaxial tests are one of the common methods to study the liquefaction behaviour of granular material. Here, the liquefaction behaviour of densely packed granular material is studied using numerical experiments with the discrete element method, for 2D particle assemblies. Cyclic biaxial loading is imposed via two boundary conditions, viz. using prescribed velocity for rigid platens and a penalty method that imposes corrective forces on the boundary particles that deviate from an affine velocity field. Simulations are performed for different void fractions of the assembly and for both boundary conditions. The initial void ratio and the boundary conditions are found to influence the liquefaction resistance of the assembly. The number of cycles for liquefaction increases with a greater constraint on the boundary. Further, the initiation to liquefaction occurs due to a gradual weakening of the force chain structure over the entire assembly. Also, particle rolling may play an important role in the rearrangement of particles and needs further exploration.