Effect of Loading/Unloading on the Earth Pressure Coefficient at Rest for Sand by DEM Analysis

Abstract The earth pressure coefficient at rest ( K 0 ) is an important parameter reflecting the relationship between the horizontal and the vertical stresses in the stratum. In the K 0 test, the relative density of soil sample will vary during loading/unloading, and K 0 value will also change accordingly during the test. Besides, different stress paths may lead to different change laws of K 0 in the test. Nevertheless, the physical mechanism about these issues is still unclear. To reveal the mechanism above from micro to macro, the Discrete Element Method (DEM) is used to simulate K 0 tests of sand with different loading/unloading processes to reflect the influence of stress paths. The results show that the contact fabric controls the stress transmission in the sample and finally makes K 0 change with loading/unloading. In addition, the overconsolidated sand has a larger K 0 than the normal consolidated sand, and the influence of stress history on K 0 is obviously enhanced during unloading.