Abstract: This paper describes an investigation of the reverse shear behavior of granular soil with fines by using the discrete element method(DEM) simulations of biaxial shear tests. The fundamental mechanisms underlying the so-called reverse behavior are scrutinized from both macroscopic and microscopic perspectives. The numerical simulation results show that the promotion of liquefaction resistance with increasing confining pressure tests mainly on the fact that as the confining pressure increases, both fine and coarse grains are to join the force chains more effectively, increasing the effective contacts between particles and thus enhancing the packing density of soil specimen as well as the stiffness of soil skeleton. The migration of fine particles in the soil skeleton plays a considerably important role in the liquefaction of granular soil with fines. It is found that during shear fine particles will be continuously dislodged into voids; and some coarse particles will also be removed from the soil skeleton due to the loss of the supporting effect from fine particles until the soil specimen is completely liquefied. In addition, fine particles are found to be mainly in weak force chains; while coarse particles are generally in strong force chains, and this has made fine particle more easily migrate in the soil skeleton as compared with coarse particles.

Key words: granular soil with fines, reverse shear behavior, discrete element method(DEM), coordination number, force chain