Water pressure could stimulate rock crack and accelerate the process of rock failure

this has an important influence on the deformation characteristics and failure mechanism of rock. A hydro-mechanical coupling test of sandy rock is conducted at different confining pressures by MTS815 Flex Test GT rock mechanics test system and PCI-Ⅱ acoustic emission (AE) system. The experimental results are displayed as follows: AE activity represents different characteristics with the loading time and stress changing during the total loading process. With the increase of water pressure

the AE activity is more concentrated and strength is higher after the stress reaches the peak strength of rock. But concentration and strength reduce with the increase of confining pressure. At the same confining pressure

the AE counts and energy increase as the water pressure increases. As the water pressure increases

the number of cracks enhances and the degree of concentration of crack is higher in the 3-D location of AE figures when the rock is unstable failure. At the same time

the failure angle decreases on the macroscopic failure morphology. These results reveal that the mechanism of rock failure changes from suppression of shear to suppression of tension rift; its plasticity is weakened and brittleness is enhanced under hydro-mechanical coupling process.