AXIAL COMPONENT OF PLASTIC MODULUS OF SAND UNDER SLOW PERIODIC LOAD

Abstract

Soil deformation under slow periodic load is of particular importance to predict the functionality of soil structure in a variety of engineering practices. However, lacking quantification on plastic deformation hinders the deformation analysis of soil subjected to slow periodic load. The axial component of plastic modulus is pivotal and is determined to calculate axial plastic strain and overall soil deformation. In this study, a static triaxial compression system was designed to perform a series of static cyclic triaxial tests and cyclic confined compression tests on a silica sand. The results showed that plastic strain increments decreased gradually, as the loading cycle proceeded, and finally only the elastic strain increment existed. The empirical equation of axial component of plastic modulus was formulated considering the effects of stress states, void ratios, and loading cycles. In combination with the description of elastic modulus, the axial strain increment in each loading cycle was formulated. In addition, in the unloading process of loading cycle, the volume contraction phenomenon was explained by unloading plastic strain and microscopic particle motion based on the present results.