Abstract: Underground rock mass is often under the coupling action of seepage field and stress field. In the aim of analyzing sandstone’s deformation characteristic, permeability characteristic, acoustic emission characteristic and fractal dimension characteristics based on the spatial distribution of acoustic emission under the same seepage pressure and different confining pressures, the author conducted triaxial seepage and acoustic emission tests on sandstone from a project under construction. Results show that 1) the compressive strength and deformation capacity of sandstone increase with the increasing of confining pressure; 2) permeability evolution is similar under different confining pressures, decreasing first and then increasing as strain grows, and decreasing gradually as confining pressure rises; 3) the evolution process of acoustic emission reflects the variation trend of permeability, which changes during the penetration test process, and the larger the confining pressure is, the more acoustic emission lags behind; 4) based on columnar fractal theory, the fractal dimension of sandstone decreases gradually during the test process, indicating that the sandstone undergoes a damage evolution process from disorder to order, and the larger the confining pressure is, the smaller the corresponding fractal dimension is. The above findings could help understand the variation mechanism of the permeability of sandstone.

Key words: sandstone, triaxial test, osmosis, acoustic emission, fractal characteristics