The physical processes triggering the fluid flow within the stressed rock are highly complex and not fully understood. In order to investigate the gas transport behaviors due to the deformation of rock, the peridotite sample from Sudbury, Canada, was subjected to the temperature-pressure effects using a special rock mechanic testing machine. It is shown that when the sample was ruptured by uniaxial compression, the connective cracks instantaneously occurred accompanied by a swarm of AE activities, which suddenly decrease the fluid pore pressure. This change can be able to drive the gas back to the emerging crack due to the gas pressure gradient within the damage zones. Once the fracture network is filled with backflow gas, gas pressure rose back quickly. The dominant components of mixed gases are carbon dioxide and methane. In addition, a large mounts of gas can be ejected from the deformed sample subjected to the confining pressure. The feature for the gas emission determined by the changes in pore structure of rock is also discussed and analyzed.
High in-situ stress in hard rock tunnel regularly triggers various types of failure such as flaking, spalling and possibly bursting of wall rock, during underground excavation at great depth (Diederichs, et al. 2004; He, et al., 2009). These disasters adversely affect both the safety and the productivity of underground coal mines all over the world. Generally, the high in-situ stress induced by compaction or thermal process tends to develop the pore pressure in fluid-filled rock systems. It is referred as abnormally pressured or overpressured. Although the pore fluid pressure applied to the rock system can relieve the rock matrix from part of the higher insitu stress, yield or failure of the rock is controlled by effective stress rather than total stresses.