Loading Rate Effects on Compressive Strength of Maha Sarakham Salt

Abstract

Uniaxial and triaxial compression tests are performed to assess the loading rate effect on the strength and deformability of the Maha Sarakham salt.  The salt specimens with a nominal dimension of 5.4´5.4´5.4 cm³ are compressed to failure using a polyaxial load frame.  The lateral confining pressures are maintained constant at 0, 3, 7, 12, 20 and 28 MPa while the axial stresses are increased at constant rates of 0.001, 0.01, 0.1, 1.0 and 10 MPa/s until failure occurs.  The salt elasticity and strength increase with the loading rates.  The elastic modulus varies from 15 to 25 GPa, and the Poisson’s ratio from 0.23 to 0.43.  The elastic parameters tend to be independent of the confining pressures. The distortional strain energy at dilation and at failure from various loading rates varies linearly with the mean strain energy.  The proposed empirical criteria are applied to determine the safe maximum withdrawal rate of a compressed-air energy storage cavern.