Studies on the Mechanical Properties of Zhoucheng Fault Gouge of Honghe Fault Zone under High Pressures

The mechanical properties of Zhoucheng fault gouge of Honghe fault zone were studied under high pressure in triaxial compression equipment with solid confining medium and at strain rate of 4.4×10-5s-1. It shows that the stress-strain curves of gouge exhibit linear and nonlinear deformation characteristics which correspond to the different deformation mechanisms of compact, yield and cataclastic flow of gouge specimen. The relations between the failure strength (σc) of gouge and the confining pressure (σэ) areσc = 23.7э30.56 (for the dry gouge)σc = 10.4э30.62 (for the moist gouge).The moisture content is an important factor which influences the deformation characteristics and the failure strength of gouge. The effective elastic moduli, Eed and Eem, of dry and moist gouge and the initial elastic modulus, Eom, of moist gouge increase with increasing confining pressure, and the initial elastic modulus, E0d, of dry gouge is nearly constant. The acoustic emission events occurre during the deformation. Under high pressure the progressive failure processes take place in the gouge specimen, so the deformation of gouge is favorable to stable sliding of the active fault.