EXPERIMENTAL STUDY ON THE INFLUENCE OF TEMPERATURE AND DAMAGE DEGREE ON THE PERMEABILITY OF SANDSTONE

The permeability of rock is related to the stability and safety of many underground projects. The temperature, stress, and self-damage in the environment of deep rock structures have a great influence on the permeability. Therefore, it is necessary to study the permeability of damaged rock under different temperatures and stresses. Permeability tests of sandstone of different damage degrees under different confining pressures and real-time temperatures were conducted by GCTS high-temperature and high-pressure dynamic rock triaxial apparatus and automatic gas permeability test system. The results show that the relation between the permeability of sandstone with different damage degrees and confining pressures exhibited a negative growth in the form of a power function. In transiting from a low confining pressure to a high confining pressure, the permeability of the highly damaged sample greatly dropped. The relation between the permeability of rock of different damage degrees and temperature was negative. The permeability of the highly damaged specimen was decreased slowly as the temperature went down. With the increase of the damage degree, the permeability of sandstone decreased slowly and then increased under a low confining pressure, and increased gradually under a high confining pressure. In addition, under low confining pressures, the difference of the permeability between the samples of higher damage degrees was larger.