近全岩保护层开采理论研究及工程实践

Theoretical research on protective seam mining in full rock stratum and engineering application

保护层开采是解决高瓦斯低透气性突出煤层的有效办法。在不具备常规煤层保护层开采条件的工程背景及技术难题基础上,提出近全岩保护层开采的技术思路。基于平煤十二矿主采煤层工程地质条件,总结了近全岩保护层开采优化设计原则,通过分析煤层膨胀变形率、应力变化特征及现有装备水平和经济技术因素,优化得出保护层与被保护层间距为12 m、保护层开采厚度为1.9 m;基于己14-31010近全岩保护层工作面煤岩体揭露情况,优选出综采液压支架、采煤机和刮板输送机等关键近全岩开采装备;设计了采煤机配合爆破预裂的破煤(岩)方式,并针对性设计单排眼和三花眼的辅助爆破工艺。实施己14-31010近全岩保护层工作面开采后,己15-31010被保护层工作面瓦斯压力由1.80 MPa降低至0.35 MPa,残余瓦斯含量仅1.28 m3/t,抽采率提高至66%,表明近全岩保护层开采瓦斯治理效果显著。

Protective seam mining is an effective way to mine out the outburst coal seams with high gas concentration and low permeability. In this paper, the technical idea of mining protective seam in rock stratum was put forward based on the engineering background and technical problems which are impossible to use conventional coal seam protective seam mining. The optimization design principle for mining protective seam in rock stratum was summarized on the basis of engineering geological condi- tions of coal seam of Pingdingshan No.12 coal mine. By analyzing the swelling deformation rate, the stress variation of coal seam, the utilization of equipment and economic and technical limitations, it was found that the optimal distance between the protective seam and the protected seam was 12 m and the optimal mining thickness of protective seam was 1.9 m. Based on the coal and rock exposure status of Ji14-31010 protective seam face in rock stratum, the key rock stratum mining equipment, such as the fully-mechanized hydraulic support, the coal cutter and the scraper conveyor were optimally selected. Acoal （rock） breaking method combining the coal cutter and pre-splitting blasting was proposed and the auxiliary blasting technologies of blast holes in a single row and three crossing rows were designed specifically. After mining Ji14-31010 protective seam in rock stratum was employed, the gas pressure of Ji14-31010 protected seam was decreased from 1.80 MPa to 0.35 MPa; the residual gas content was only 1.28 m3/t; the extraction rate was increased to 66%. Therefore, mining protective seam in rock stratum achieved a significant gascontrol effect.