Physical experiment and numerical simulation of sand-structure interface's direct shear

The physical experiment and numerical simulation of sand-structure interface direct shear were conducted by using DRS-1high normal stress residual shear apparatus and PFC2D (Particle Flow Code in 2 Dimensions) software. The macroscopic representation and inherent mechanism of the mechanical properties of sand-structure interface were obtained. The results show that the strain softening weakens and strain hardening heightens as the roughness increasing under certain normal stress. At same time, the shear displacement corresponding to the peak shear stress reduces gradually. The influence of surface roughness reduces as normal stress increaseing. For the same structure, shear strength at the sand-structure interface meets Mohr-Coulomb criterion. In a certain normal stress conditions, soil particles shear dilation is one of the main reasons which cause the shear strength of the sand-structure interface to change without considering the particle breakage. When the relative roughness R (which is defined as the ratio of peak-valley distance to average particle size, R=H/d50) is smaller, soil particles shear dilation caused by interface constraint and the peak shear stress are all smaller. Both soil particles shear dilation caused by interface constraint and the peak shear stress increase as the relative roughness R increasing. When R increases to a certain degree, soil particles shear dilation caused by interface constraint becomes small. So the peak shear stress reduces too. ©, 2015, China University of Mining and Technology. All right reserved.