Experimental Study on The Influence of Effective Stress on Stress Sensitivity of Coal Permeability

Abstract

In order to study the influence of effective stress on the sensitivity of coal permeability stress, three groups of low permeability dense coal samples were selected in the range of confining pressure of 2 MPa ~ 4 MPa. Under the influence of single factor of effective stress, the cross-contrast seepage experiment of coal samples under different effective stress conditions was carried out by using steady seepage method, and the variation characteristics of effective stress sensitivity of coal samples were systematically analyzed by using permeability damage rate and permeability curvature. The results show that: (1) under various confining pressures, with the increase of effective stress, the damage rate of coal permeability decreases according to the law of negative exponential function, and the greater the effective stress, the greater the damage rate of coal permeability; (2) The effective stress is constant, the smaller the confining pressure is, the greater the curvature of permeability is, the greater the influence of effective stress on coal seam permeability is, and the stronger the sensitivity is.