Effects of stress paths on triaxial compression mechanical properties of QH-E lunar soil simulant studied by DEM simulation

In this paper, three different stress paths [conventional triaxial compression (CTC), constant principal stress triaxial compression (PTC), and hydrostatic compression (HC)] are chosen to investigate the effects of stress paths on the mechanical properties of QH-E lunar soil simulant by using discrete element method simulation. The results show that under HC path, only volumetric change occurs, the volumetric strain increases quickly first, and then increases slowly and becomes more and more flat as the confining stress increased gradually to the conventional level. Under CTC and PTC paths, QH-E lunar soil simulant generates strain softening and shear dilatancy, the shear dilatancy parameters (linear shear dilatancy, residual shear dilatancy and residual shear dilatancy point) with confining stress show a good linear relationship, the value of linear shear dilatancy is larger than that of residual shear dilatancy, and the slope of regression line under CTC path is higher than that of PTC path, which indicates that the increase speed of volumetric strain under CTC path is faster than that of PTC path. Under the same confining stress, the peak deviatoric stress under CTC path is larger than that of PTC path, and a higher confining stress leads to a greater difference between CTC and PTC paths obtained the peak deviatoric stress. The results provide important information for understanding the stress path-dependent mechanical properties of lunar soil simulant. Graphical Abstract