CONFINING PRESSURE EFFECT ON THE PERMEABILITY AND MECHANICAL BEHAVIOR OF SANDSTONE UNDER A CERTAIN PORE WATER PRESSURE CONDITION

In geotechnical engineering, the mechanical behavior of rocks under various In-situ conditions (stress state including axial stress, confining pressure, pore water pressure) have always been an important topic. Therefore, the confining pressure effect on the permeability and mechanical behavior of different size sandstone samples under a certain pore water pressure condition was studied. The permeability of different sizes samples shows roughly the same exponential de-creasing law with the increase of confining pressure. In the mechanical behavior test, both the loading Young's modulus E+ and the unloading Young's modulus E- increased continuously with increasing confining pressure, while the unloading Poisson's ratio .- decreased to a certain value and then remained almost constant.