Research on energy evolution characteristics and stability of coal pillar-roof structure

Abstract

The occurrence of coal mine accidents is mostly caused by the instability and failure of the coal pillar and its overlying roof rock layer. To study the influence of different coal-rock height ratios on the deformation failure and energy evolution mechanism of the coal pillar-roof system, uniaxial loading and cyclic loading and unloading tests are conducted on coal-rock structural body with coal-rock height ratios of 1∶3, 1∶2, 1∶1, 2∶1, and 3∶1, respectively. The relationship between deformation and energy evolution of coal-rock structural body are analyzed, and the stability of coal-rock structural body are quantitatively evaluated through the load-unload response ratio. The test results show that the peak strength of coal-rock structural body under uniaxial loading and cyclic loading gradually decreases with the increase of coal-rock height ratio. The peak strength of coal-rock structural body under cyclic loading test is lower than that in uniaxial loading test. The higher the coal-rock height ratio, the smaller the reduction rate of the peak strength of the structural body under cyclic loading; the input energy, elastic energy and dissipative energy of the composite increase nonlinearly with the increase of stress. The coal-rock height ratio is positively proportional to the average elastic strain, average elastic energy, average residual strain, average dissipative energy, total residual strain and loading and unloading response, and inversely proportional to the total elastic strain, total elastic energy and total dissipative energy of the composite during cyclic loading.

Keywords

• rock layer instability
• coal-rock height ratio
• coal-rock structural body
• deformation characteristic
• failure characteristics
• energy evolution mechanism
• surrounding rock control