Experimental study on effect of effective stress on permeability of coal

Abstract

In order to study the influence mechanism of effective stress on permeability, the coal permeability test experiment under simultaneous loading of axial and confining pressure was carried out using the self-developed coal-rock gas adsorption-desorption-seepage platform. The mean effective stress parameter is introduced to characterize the loaded state of the coal body. At the same time, in order to eliminate the influence of the individual differences of the specimens, the effective stress sensitivity coefficient is defined, and the control mechanism and variation law of the effective stress on the permeability of the coal body are discussed in depth. The results show that when the gas pressure remains constant, the coal permeability decreases gradually with the increase of the effective stress, and its variation law conforms to the negative exponential relationship. With the increase of effective stress, the sensitivity coefficient gradually decreases, and it conforms to the power function relationship. At the same time, a mathematical model of coal sample permeability and effective stress is constructed based on the sensitivity coefficient.

Keywords

• permeability
• synchronous loading
• effective stress
• sensitivity coefficient
• mathematical model