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保护层开采是高突矿井瓦斯治理的主要方式及开采方法,然而其卸压增透效果当前无法量化表征,缺乏评价体系。基于平板流体模型增透率理论,结合平煤十矿地质条件,通过离散单元法建立保护层开采数值模型,获得保护层开采不同距离时采空区下方的增透率图谱及被保护层的应力分布。结果表明:保护层开采过程中,采面前方15 m处支撑压力会出现应力峰值,随着采面的推进,增透率与现场瓦斯流量呈现正相关关系;在采空区下方,被保护层卸压及增透效应明显,且卸压区范围与增透率分布集中区域基本一致,均随采空区范围的扩大而增大。该研究成果证实了增透率理论可作为保护层开采卸压增透指标,为现场保护层回采设计、瓦斯抽采设计范围的确定提供更加科学的依据。
The mining of protective layer is the main method and mining method of gas control in high-outburst coal mine. However, the effect of pressure relief and permeation enhancement is not quantifiable at present and lacks the evaluation system. Based on the permeability theory of flat plate fluid model and the geological conditions of Pingdingshan No. 10 mine, a numerical model of protective layer mining was set up by discrete element method to get the maps of the permeability underneath the gob and the stress of the protected layer distributed. The results show that during the mining process of protective layer, the stress peak appears at the support pressure of 15 m in front of the mining face. As the mining face advances, the permeability increases positively with the on-site gas flow rate. Under the goaf, The pressure relief and antireflection effects are obvious, and the range of pressure relief zone and the distribution of permeability increase are basically the same, both of them increase with the expansion of the area of goaf. The results of this study confirm that the theory of permeability can be used as an indicator of depressurization and permeability enhancement in the protective layer mining and provide a more scientific basis for the design of on-site protective layer recovery and the determination of the design range of gas drainage.