Effects of Sample Preparation Method on Sand Liquefaction Mechanical Properties with Discrete Element Simulation

Abstract:

PFC2D software was used to simulate sand samples prepared by moist tamping method and deposition method. Undrained cyclic loading tests were performed on samples to analyze the microstructure changes during the dynamic loading process. The test results indicated that the long axis direction of sand particles tended to distribute horizontally on the compression side but vertically on the extension side when cyclic loading was applied. Although the distribution of the normal directions of particle contacts was contrary to the long axis direction， both anisotropy coefficients were increased gradually with the increasing of cyclic number. Besides， the coordination number of the samples decreased and finally fluctuated within the range of 0-3 after liquefaction. The samples obtained from moist tamping method exhibited less anisotropy than the deposition samples. Thus， the former one required more loading cycles to reach liquefaction， which implies the layered samples owned higher resistance to liquefaction. The differences in liquefaction resistance between two samples were more obvious for dense sand than medium-dense sand.

Key words:sand liquefaction;sample preparation method;numerical simulation;sand fabric