Experimental investigation on strength and deformation properties of anhydrite under conventional triaxial compression

Experiments were carried out to study the strength and deformation properties of anhydrite under conventional triaxial compression by servo-controlling testing machine. The experimental results indicated that failure surface was shear failure under low confining pressure; when the confining pressure up to 10 MPa, anhydrite behaves obvious plastic flow characteristic; under confining pressure of 18 MPa, these was no obvious failure surface, that is shown volume expansion. It is approximately linear relationship between peak strength and confining pressure. The peak strain and elastic modulus varieties under different confining pressures were also analyzed. The results indicate that the peak strain and elastic modulus increase with confining pressure increase. Protracted Mohr circle envelope curve using triaxial compression results. Regression analysis strength criteria and shear strength parameters c.., the presented results can be expected to provide useful references to the analysis of underground engineering.