Evolution rules and effects of particle breakage for quartz sand in triaxial shear tests under high pressures

The particle breakage of sand under high stress is obviously different from that under the normal stress. The existing studies on the evolution rules and models of particle breakage for quartz sand under high stress are relatively limited. A series of consolidation drained (CD) and consolidation undrained (CU) triaxial shear tests are conducted under the confining pressures of 2~8 MPa to investigate the evolution rules of particle breakage for quartz sand and its effects on sand strength. The relationship curves of deviated stress-axial strain under various stress levels are obtained as well as the relative breakage during shear process. Then the evolution rules of particle breakage are analyzed, the Hardin's, Lade's and Wang's particle breakage models are adopted to describe the rules, and the applicability of each model is discussed. Finally, the critical relative breakage of quartz sand that affects sand strength under high pressures is given based on the relationship between the relative breakage and the effective failure internal friction angle.