Influence of stress paths including principal stress rotation on critical state of dense sand

Traditional research about the critical state of sand is mainly focused on the uniqueness and linearity of the critical state line. But stress path and principal stress rotation, as two important factors, have always been neglected, not to mention being studied simultaneously. And the principal stress rotation of sand cannot be observed in laboratory test. In order to make up for the shortage and combine the traditional stress path and stress path that reflects principal stress rotation, this paper conducts numerical simulations of biaxial tests and simple shear tests for dense sand by using particle flow code. According to the results, it is found that: (1) the critical state line is unique and not affected by the stress path, principal stress rotation drainage condition, initial void ratios and confining pressures; (2) the critical state lines in both effective pressure-deviatoric stress space and effective pressure-specific volume space change from a straight line under low critical values to a curve under high critical values. Then the simplification of stress path is relatively inappropriate. Different stress paths, especially which include unconventional and specific paths will greatly influence the characteristics of critical state line. Therefore, the study about effects of different stress paths on critical state is valuable and should be paid great attention to.