Influence of Particle Breakage on Drained Shear Strength of Calcareous Sands

摘要

The consolidated drained triaxial shear tests have been performed in this work to investigate the shearing behavior of calcareous sands sampled from the South China Sea, with the focus on analyzing the influence of particle breakage on the materials shear strength. At approaching the failure limit state, the intense particle breakage and rearrangements prevented the shear stress from increasing further. Depending on the initial packing density, the loose sand sample exhibited the strain-hardening response, while the dense sand sample exhibited the strain-softening response with clear shear dilatancy after the peak shear strength has been reached. However, when the confining pressure increased, particle breakage occurred more thoroughly, and the sharpness of the peak stress disappeared gradually. For the series of tests, an upper limit of relative particle breakage existed, beyond which the confining pressure and relative density had little influence on the breakage of particles. The shear strength of calcareous sands was found to be determined by the combined effects of interparticle friction, sample dilatancy, and particle breakage. Under low confining pressures, the shear strength was mainly controlled by particle friction and sample dilatancy, while under high confining pressures, the effect of particle breakage was dominant. In this process, the volumetric strain evolved from dilation to contraction and the sample dilatancy angle decreased gradually. After breakage, the particle shape transformed from highly angular to subrounded.