Experimental Study on Acoustic Emission of Coal and Rock underSeepage-creep Coupling Action

In order to explore the acoustic emission and damage characteristics of coal and rock under seepage-crreep coupling action, creep acoustic emission tests were carried out with four different groups of seepage pressure and confining pressure. The research results showed that the cumulative flow curves corresponded to the creep curves and can be divided into three stages of the initial, steady state and acceleration; affected by the mutual influence of the seepage and creep action and under the same confining pressure, the greater the seepage pressure of coal and rock, the greater the instantaneous strain of them, the higher the creep rate, the greater the amount of seepage and the more active the acoustic emission; under the same seepage pressure, the greater the confining pressure, the smaller the instantaneous strain of coal and rock, the lower the creep rate, the smaller the amount of seepage and the active degree of the acoustic emission decreased; in the seepage-creep process, the acoustic emission presented an overall U-shaped change, the volume compression was transformed to the volume expansion period, the acoustic emission was extremely active, this indicated that the coal and rock were in a transition period of their internal structure adjustment and damage state at this time; the damage based on the Weibull distribution function indicated that the coal and rock were all had a damage threshold value under different confining pressures, and when the damage exceeded this threshold value, the coal and rock entered the accelerated creeping deformation stage, and the damage threshold value tended to increase with the increase of the confining pressure.