Abstract: Cemented sand and gravel material has received widespread attention for its superior properties.In order to explore its destructive characteristics under the coupling of seepage-stress, based on a new mesoscopic discrete model, the lattice discrete particle model, a numerical simulation model of cemented sand and gravel material under coupling of seepage and stress is established.Combined with results of the triaxial compression test, the model parameters are calibrated.By comparing the results of the wedge splitting test under different water pressures, the applicability of the model is verified.The results show that with the increase of water pressure, the peak load and the corresponding crack opening displacement decrease, and the cyclic loading times before failure are reduced.Through mesoscale failure mechanism analysis, it is found that with the increase of water pressure, the process zone of crack propagation becomes shorter, water is more easily to inject into the crack tip, and the failure mode of material tends to be brittle failure.It provides a calculation model and reference for the failure behavior analysis of cemented sand and gravel dams and cofferdams under the hydromechanical coupling situation.