Abstract
Stress is one of the main factors influencing coal and gas outbursts. The apparent effects of the crustal stress, the structural stress, and the mining-induced stress increase as the depth of mining increases. At present, there have been few studies of the relationship between the comprehensive analyses of the crustal stress, mining-induced stress, and coal gas. The in situ measurement of the relationship between stress-related behaviors and coal gas under the influence of mining was conducted through experimental analysis of surrounding rock support and coal and gas outburst control and optimization of surrounding rock support materials and system construction. The results showed that the mining-induced stress first increased to a peak value, then gradually decreased, and tended to stabilize as the footage progresses. Stress appears at 96 m ahead due to mining; after 57 m of advancing, there is a large increase until it passes through this area. The stress in front of the working face increases linearly, and the increase range is obviously larger than that of the coal body in a certain range on both sides. The support anchoring force gradually decreased and tended to be stable after rapidly increasing to a maximum value. The deep displacement of the roof increased linearly and tended to be stable after reaching an accumulated displacement which can reach 16-28 mm. The residual gas pressure in front of mining operations decreased rapidly, and beyond 15 m on each side of the roadway, it decreased significantly. The residual gas pressure and gas content were consistent with the gas desorption index of drill cuttings due to the influences of gas predrainage and mining. The stress along the direction of the roadway and the residual gas content, the residual gas pressure, and the gas desorption index of drill cuttings conform to the logarithmic functional relationship. The research results provide a basis for the comprehensive prevention and control of coal and gas outbursts from multiple angles considering stress, coal, and gas.
Highlights
With the development and exploitation of mines to greater depths, it is difficult to predict and control deep coal mining disasters because of the high crustal stress, high permeability, and high gas pressure and gas content, as well as the additional attributes of strong disturbance and timeliness in deep mining
It is generally believed that coal and gas outbursts are the result of comprehensive action of the crustal stress, gas, and physicomechanical properties of coal, in which the crustal stress is a stimulating factor high-pressure gas plays a decisive role in the development of outbursts and the physicomechanical properties of coal form obstacles to outbursting [2]
The derivative effect under the influence of mining can lead to rock bursting and coal and gas outbursts, so the stress evolution characteristics induced by mining have been widely studied
Summary
With the development and exploitation of mines to greater depths, it is difficult to predict and control deep coal mining disasters because of the high crustal stress, high permeability, and high gas pressure and gas content, as well as the additional attributes of strong disturbance and timeliness in deep mining. The derivative effect under the influence of mining can lead to rock bursting and coal and gas outbursts, so the stress evolution characteristics induced by mining have been widely studied. The relevant laws and regulations have given quantitative provisions as to the basic parameters of coal and gas outbursts and the characteristics of a coal body, but the influence of stress-related factors has not been quantified. Under this background, it is essential to measure and analyze the mining stress, support stress, surrounding rock deformation, and coal gas parameters based on the optimization of stope support and study the relationship between coal stress and coal gas under the influence of mining
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