Effects of non-plastic fines on liquefaction properties of saturated silt using discrete element modeling

This paper presents a numerical investigation using the three-dimensional discrete element method (DEM) to evaluate the macro-scale properties of saturated silt in a cyclic triaxial test. The three-dimensional particle model generated based on scanning electron microscopy (SEM) images of silt was imported into the discrete element program PFC3D and a rigid block model with different fines content was established. The effect of non-plastic fines content on the liquefaction properties of silty rigid block model was studied. The DEM results show that: (1) In the initial stage of dynamic stress loading, the axial strain of the sample develops slowly, and the stress -strain hysteresis loops almost overlap. With the increase of the number of cycles, the axial strain fluctuates violently, and the hysteresis loop becomes larger and develops toward the transverse axis. After the initial liquefaction, the dynamic elastic modulus and strength of the sample decrease significantly. (2) When the fines content increases from 0 to 30%, the liquefaction resistance of silt decrease with the increase of fines content. When the fines content increases from 30% to 100%, the liquefaction resistance of silt increases with the increase of fines content. (3) Under the same cyclic stress ratio, the number of cycles required for silt to liquefy decreases initially and then increases with the increase of fines content, and the critical fines content is 30%. The DEM results were compared with experimental results from the laboratory cyclic triaxial tests to provide insights into the underlying mechanism that governs the effects of fines content value on the liquefaction properties of silt.