Experimental study on shear characteristics of sand under high pressure

For mastering the strength and deformation properties of sand under high pressure, DRS-1 high pressure direct shear test system was used in shear test of Fujian standard sand under 12 to 15 MPa. Through analysis of the test results, we obtained that shear properties of standard sand under high pressure show strain hardening, it is consistent with Duncan-Chang hyperbolic model. There is a proportional relationship between shear stress τ and vertical stress σ _n while ε s becomes infinite, which is obtained from the relationship between ε _s/τ and ε s. Under high pressure, the friction coefficient of standard sand´s shear failure surface increases with shear strain. The value does not change with vertical stress σ _n and the final stable value is about 0.46. Shear properties of standard sand under high pressure show volume contraction which can also simulated by Duncan-Chang hyperbolic model. The relationship between volume contraction ε ν and σ _n is similar to Mohr Coulomb criterion when the sand sample is damaged.