The effect of particle size and degree of saturation on liquefaction potential of sandy soil

In recent years, studies on strength characteristics of unsaturated soils due to the importance of suction in these types of soils has been more focused on cohesive fine-grained soils or compacted sandy soils and limited research on liquefaction of loose unsaturated sandy soils and the effect of particle size on this behavior have been done. In this paper, it has been aimed to investigate the effect of particle size and degree of saturation on liquefaction resistance of loose unsaturated sandy soils by performing a series of cyclic triaxial tests at undrained conditions on three types of sand with different grain size distribution. The results show that variation of pore water pressure and liquefaction resistance in studied sands are largely dependent on particle size and intergranular voide ratio, so that #131 Firoozkooh sand has the lowest liquefaction resistance in saturated state due to its higher intergranular voide ratio. Also, according to the obtained results, increasing the size of sand grains reduces the matric suction created in the soil mass due to reduction in degree of saturation. Increase of number of cycles to liquefaction and consequently the liquefaction resistance of the stadied sands samples due to decrease of saturation, especially in sands with finer grains, is another result of this study.