Experimental Study On The Law Of Coal Deformation And Permeability In Gas Emission

In the process of gas emission, the stress changing, pore pressure changing and coal desorpting gas can cause coal deformation. The deformation affects coal pores and fractures in the body and then the permeability of coal. Study the laws of coal deformation and seepagegas during the process of gas emission, provide important theoretical basis for exploring the mechanism of coal and gas outburst and other dynamic disasters.The paper study the briquettes made by 9# Tiexin coal mine, use self-developed desorption-seepage-stress deformation test apparatus, make the experiments of coal mass deformation under stress, the experiments of coal mass deformation under stress-seepage and the experiments of coal mass deformation under desorption-seepage-stress. Explore deformation and permeability law under the action of seepage,stress,desorption during the process of coal gas emission by changing confining pressure, axial pressure and pore pressure of coal samples.By experimental results of deformation under the action of stress:When the effect of coal stress is only considered, the deformation changes linearly with pressure. By experimental results of deformation under the action of stress and seepage:When the effect of pore pressureis only considered, the deformation increases with the increasing of pore pressure, the relationship can be expressed in a quadratic function, the permeability of coal firstly increases and then decreases with the increase of pore pressure; Under the effect of confining pressure and pore pressure, the relationship of coal strain, pore pressure and confining pressure can be expressed in functional form ?= Ap²+Bp+C?₃²+D?₃+E; By experimental results of deformation under the action of stress-seepage-desorption:Under the effect of stress, seepage and desorption, with the decrease of pore pressure, coal samples shrink, lateral strain decreases faster than longitudinal strain; When the confining pressure decreases, lateral deformation which desorption and seepage caused increases gradually, but the longitudinal strain decreases; It can be expressed in quadratic function of the relationship between strain and pore pressure in the test the pore stress range; permeability increases with the decrease of the pore pressure, and decreases with the increase of confining pressure. Compare deformation under the action of the stress-seepage and deformation under the action of stress-seepage-desorption, it can get:the relationship between pore pressure and desorption deformation can be described as Langmuir equation; The permeability of coal under the action of desorption-seepage is smaller than the action of seepage, coal permeability will increase gradually during the process of gas emission.