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Abstract
In China, coal‐gas outburst is seriously affecting safety of the coal mine. To improve the safety status of underground coal mining, this work investigated the evolution process and occurrence mechanism of coal‐gas outburst under the coupling action of stress and gas. Results show that increasing either gas pressure or in‐situ stress can make coal destroy and destabilize, and the contribution of gas pressure to coal failure is twice that of in‐situ stress. In ultradeep coal mining, coal‐gas outburst may occur even under the condition of low gas pressure due to large in‐situ stress. Moreover, the larger the mining depth is, the lower the gas index is required for disaster occurrence. The results have certain guiding significance for coal energy mining and the control of coal‐gas outburst in deep coal mining.
Highlights
With the development of society, people’s demand for mineral resources has gradually increased, and coal mining has gradually shifted to the deep part of the earth, leading to more and more dynamic disasters during the production, which poses a threat to the safety of energy and miners’ lives [1, 2]
Gas dynamic disasters are still one of the important research directions of safety science, and the frequency of occurrence is increasing, which poses a threat to the safety of miners’ lives and property. It is beneficial for controlling the occurrence of disasters to reveal stress-gas coupling function and the occurrence law of gas dynamic disaster under the condition of deep mining. e main conclusions of this paper are as follows: (1) e maximum circular stress at the crack tip showed a trend of decrease with the increase of the angle between the crack and the maximum principal stress and increases linearly with the increase of gas pressure and ground stress. e destructive capacity of increasing the same gas pressure on the coal body is about twice of that of the ground stress and had a negative power function relationship with the friction coefficient of coal
(2) In the process of dynamic disaster, crack propagation and penetration of coal under the joint action of ground stress and gas pressure is an important gestation stage. e superposition of large tectonic stress and mining stress in the geological structural zone can cause crack expansion and penetration, leading to fully broken of the coal body, which is prone to dynamic phenomena
Summary
With the development of society, people’s demand for mineral resources has gradually increased, and coal mining has gradually shifted to the deep part of the earth, leading to more and more dynamic disasters during the production, which poses a threat to the safety of energy and miners’ lives [1, 2]. From the aspects of coal cracks gestation and propagation as well as the fracture mechanics, massively studied coal and gas outbursts and similar dynamic disasters are caused by coal destabilization. Zhao et al [23] used a 3D mesoscopic monitoring software for dynamic evolution of the coal surface microstructure as the main research equipment to examine the propagation law of cracks on the coal surface under impact load He and Wang [24] further analyzed the general law of the deformation and failure process of a composite from the aspects of both damaged crack evolution process and the mechanics of interactions of different media. En, based on the theory of strain energy density factor, the influence of in-situ stress, gas pressure, and physical and mechanical properties of coal on the internal crack growth of the coal body is studied. Our conclusions can provide a theoretical basis for more accurate prediction of coal and gas outburst and more reasonable determination of predictive indicators
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