采动条件下被保护层瓦斯卸压增透机理研究

保护层开采作为一种典型的煤与瓦斯安全开采形式在煤矿生产中具有重要的意义。通过由半无限开采积分模型求解得到的岩体内部位移场表达式并与相似模拟被保护层沉降曲线对比，研究发现理论模型可以较好地反映煤层实际变形。建立了“两带”裂隙分布模型及其简化力学模型，通过正交设计的全应力应变渗透试验发现，瓦斯渗透主要分为3个过程，发现瓦斯渗透急剧变化在体积应变达到0.015处，对比理论体积应变分布曲线，得出体积应变沿沉降范围总体上呈对称分布，在中心区域存在一个体积应变大于0.015的范围，可见其正处于渗透率急剧增加阶段，其卸压增透效果最好。研究结果为被保护层瓦斯卸压增透计算提供了参考。

Mechanism of unloading-induced permeability increment of protected coal seam under mining

Protective coal seam mining has great significance in coal production as a typical form of safe mining of coal and gas simultaneously. The displacement field expression within the rock mass can be solved by means of the semi-infinite integral model, and the actual deformation of coal seam can be better explained by the theoretical model through contrast to subsidence curves of protected coal seam of similar simulation tests. A two-zone crack distribution model as well as the simplified mechanical model is established. It is found that there are three processes of gas permeability from the orthogonal design of the complete stress-strain penetration tests, which has a dramatic change in the volumetric strain of 0.015. The law of symmetrical distribution of volumetric strain along settlement range can be obtained by comparing the theoretical volumetric strain distribution curve, which has a sharp increasing penetration rate in the range, which is larger than 0.015. The results will be useful for the calculation of gas permeability induced by the pressure relief of protected coal seam.