Experimental study on effect of water on creep acoustic emission characteristics of coal containing pores

Water is the main factor affecting the stability of coal and rock. In order to comprehensively analyze the influence of water on the creep acoustic emission characteristics of coal and rock around the borehole, single-hole samples with water contents of 0, 4%, 8% and saturated water content were prepared in the laboratory in this paper. The grading loading creep acoustic emission test was carried out to obtain the creep acoustic emission law of coal and rock around the borehole under different water content. According to the creep acoustic emission test under graded loading under different water contents, the creep acoustic emission law of coal and rock around the borehole under different water content was obtained. The test results show that: ① The change of water content affects the creep mechanical properties of the surrounding rock mass, and the creep transient strain and steady-state strain increase exponentially with the increase of water content, and the strain increase of saturated water sample is greater. Obviously, the maximum increase of instantaneous strain and steady-state strain reaches 44.5% and 28.6%. ② The water content affects the cumulative ringing count and axial strain during the creep process. The axial strain increases with the increase of water content, and the cumulative ringing count increases linearly with the increase of axial strain. The higher the rate, the greater the increase of the cumulative ringing count. Under different stress levels, the increase and decrease of the accumulative ringing count of the samples with water contents of 4%, 8% and saturated water content basically maintained at 43%, 53% and 74%. ③ The acoustic emission ringing rate has a trend of increasing-decreasing-stabilizing in each stage of creep. As the water content increases, the acoustic emission activity decreases significantly, and the creep curve is temporally relative to the acoustic emission data. There will be a hysteresis effect. The research provides guidance for gas drainage, borehole protection and acoustic emission detection.