NUMERICAL INVESTIGATION OF DIFFUSE INSTABILITY IN SANDY SOIL USING DISCRETE ELEMENT METHOD UNDER PROPORTIONAL STRAIN PATH LOADING

Abstract

THE LOOSE SANDY SOIL CAN MANIFEST STATIC LIQUEFACTION PHENOMENON UNDER UNDRAINED CONDITION AND THE ONSET OF INSTABILITY IS WITHIN THE FAILURE LINE, AND THERE IS NO OBVIOUS SHEAR BAND. THIS TYPE OF FAILURE MODE, VERY DIFFERENT FROM LOCALIZED INSTABILITY THAT OCCURS IN DENSE SAND, IS CALLED THE DIFFUSE INSTABILITY. IN THIS PAPER, A SERIES OF PROPORTIONAL STRAIN TESTS AND FULLY DRAINED TESTS UNDER DIFFERENT INITIAL VOID RATIO AND DIFFERENT STRAIN INCREMENT RATIO ARE SIMULATED USING THE DISCRETE ELEMENT METHOD. THE INFLUENCE OF STRAIN INCREMENT RATIO AND THE INITIAL VOID RATIO TO AFFECT THE INSTABILITY OF SANDY SOIL ARE DISCUSSED IN DETAIL. THE DEVELOPMENT MECHANISM OF PORE WATER PRESSURE IN PROPORTIONAL STRAIN TESTS IS ANALYZED BY COMPARING WITH THE VOLUMETRIC CURVE OF FULLY DRAINED TEST. A UNIFIED MECHANISM OF DIFFUSE INSTABILITY OF SANDY SOIL IN PROPORTIONAL STRAIN TESTS IS EXPLAINED, AND A PARAMETER TO REFLECT THE LIQUEFACTION POTENTIAL OF SANDY SOIL IS PUT FORWARD.