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Title:: Shear Dilatancy and Shear Shrinkage Characteristic of Sand and Its Influence on Shear Strength

Author(s):: XU Cheng-shun; LI Yan-mei; GENG Lin; DAI Jin; Key Laboratory of Urban Security and Disaster Engineering, Beijing University of Technology

Keywords:: saturated sand soil; pure torsional shear test; excess pore water pressure; volume strain; shear dilatancy and shear shrinkage; shear strength

Abstract:: In order to study the shear dilatancy and shear shrinkage characteristic of saturated sand soil and its influence on shear strength, the Hutuo River fine sand was selected and the hollow cylindrical torsional shear apparatus was used to carry out a series of experimental research on the drainage and undrained pure torsional shear under different initial densities and different consolidation pressures. The shear dilatancy and shear shrinkage characteristics of sand soil were studied under the condition that the total stress remained unchanged. The stress-strain relationship, hardening and softening, shear dilatancy and shear shrinkage characteristics and strength of sand soil with different densities and different effective confining pressures under the action of monotonic shear load in the drainage and undrained tests were discussed. The results show that the effects of sand density and consolidation pressure on shear dilatancy and shear shrinkage characteristics of sand soil are significant. The shear dilatancy and shrinkage characteristics of sand soil have significant effects on the drainage, undrained strength and stressstrain relationship. Due to the influence of shear dilatancy and shear shrinkage characteristics, the undrained shear strength of sand soil may even be higher than that of drained shear strength. The research results can provide experimental data for future constitutive models and numerical simulations.