Abstract: Water-bearing sandstone is widely distributed in the roof of primary mining coal seam of Ningdong coal field, which is prone to deformation and instability. In this experiment component of water-bearing sandstone is quantitatively analyzed, and time relationship between drying and water suction of sandstone is also studied. Research shows that this kind of sandstone is rich in clay minerals, and the variation of moisture content tends to keep stable six hours after being dried and soaked respectively; moreover, uniaxial compressive strength and elastic modulus of the sandstone decrease on the scale of exponential function with the increase of moisture content. The results of acoustic emission characteristics experiment show that count peak of acoustic emission of sandstone samples corresponds to the peak stress under the condition of being dried and lags behind with the increase of moisture content which shows “delaying” characteristics; in the mean time, pulse count decreases significantly with the peak of energy. According to these, technical thoughts are put forward to predict and forecast the stability of such kind of sandstone roof.

Key words: uniaxial compression, water-bearing sandstone, strength deterioration, AE characteristics