A numerical model is developed to simulate saturated granular soil, based on the discrete element method. Soil particles are represented by Lagrangian discrete elements, and pore fiuid, by appropriate discrete elements which represent alternately Lagrangian mass of water and Eulerian volume of space. Macroscale behavior of the model is verified by simulating undrained biaxial compression tests. Micro-scale behavior is compared to previous literature through pore pressure pattern visualization during shear tests. It is demonstrated that dynamic pore pressure patterns are generated by superposed stress waves. These pore-pressure patterns travel much faster than average drainage rate of the pore fiuid and may initiate soil fabric change, ultimately leading to liquefaction in loose sands. Thus, this work demonstrates a tool to roughly link dynamic stress wave patterns to initiation of liquefaction phenomena. A numerical model is developed to simulate saturated granular soil, based on the discrete element method. Soil particles are represented by the Lagrangian discrete elements, and pore fiuid, by appropriate discrete elements which represent alternately Lagrangian mass of water and Eulerian volume of space. Macroscale behavior of the model is verified by simulating undrained biaxial compression tests. Micro-scale behavior is compared to previous literature through pore pressure pattern visualization during shear tests. It is said that dynamic pore pressure patterns are generated by superposed stress waves. These pore-pressure patterns最终 成为 liquefaction in loose sands. eventually, leading to liquefaction in loose sands.