中国煤的燃烧变质作用与煤层自燃特征

我国西北地区烧变岩分布范围广、孔隙裂隙发育、富水性强，是当地的主要含水层，其中的隐伏火烧区烧变岩地表遗迹不明显、发现难度大，煤矿开采一旦导通烧变岩含水层将导致水害事故，同时会破坏烧变岩含水层水资源。为治理隐伏火烧区烧变岩水害并保护烧变岩含水层水资源，分析我国烧变岩分布特征及烧变岩水对煤矿开采影响，研究隐伏火烧区烧变岩探查和治理技术，开展隐伏火烧区烧变岩含水层水害治理的示范应用，结合现场监测数据分析评价陕西柠条塔煤矿南翼隐伏火烧区含水层水害治理和水资源保护效果。结果表明：我国烧变岩主要分布于以昆仑山−秦岭−大别山为界的北方地区，隐伏烧变岩主要分布在鄂尔多斯盆地东北部、伊犁盆地南缘，被第四系松散层覆盖；隐伏火烧区烧变岩含水层与风化基岩含水层大多直接接触且连为一体，水力联系密切；烧变岩水害防治措施主要有留设烧变岩含水层防隔水煤柱、疏降烧变岩含水层积水和帷幕截流，其中截水帷幕可有效解放烧变岩含水层压覆的煤炭资源，解除烧变岩水害威胁并保护烧变岩含水层宝贵的地下水资源；通过精确探查出隐伏火烧区范围、布设注浆钻孔，将隐伏火烧区烧变岩含水层隔离为若干个含水体，断绝截水帷幕内外的水力联系，可保障工作面不受烧变岩水威胁，同时实现烧变岩水资源保护；柠条塔煤矿S1232工作面和S1233工作面隐伏火烧区烧变岩含水层治理后，其回采期间涌水量降至20 m³/h以内，工作面得以安全回采，截水帷幕内侧水位下降，外侧水位逐渐抬升，烧变岩水资源得到有效保护。

Combustion metamorphism and spontaneous combustion characteristics of coal seams in China

Burnt rocks are extensively distributed in northwestern China, featuring well-developed pores and fractures and abundant water, emerging as primary aquifers in this region. The burnt rocks in concealed burnt areas in this region show inconspicuous surface remains, complicating their identification. Penetrating burnt rock aquifers in coal mining will lead to water hazard and destroy water resources in these aquifers. To prevent and control water hazard in burnt rocks within concealed burnt areas and preserve water resources in burnt rock aquifers, this study analyzed the distributions of burnt rocks in China and the effects of water in them on coal mining. Furthermore, it delved into technologies for the exploration and water hazard control of burnt rocks in concealed burnt areas and conducted exemplary application. By combining the field monitoring data, it analyzed and evaluated the performance of water hazard control and water resource preservation in the concealed burnt area on the south flank of the Ningtiaota Coal Mine in Shaanxi Province. The results are as follows: (1) China’s burnt rocks are primarily found across the northern region bounded by the Kunlun-Qinling-Dabie mountains. Among them, concealed burnt rocks, covered by Quaternary unconsolidated strata, are primarily distributed in the northeastern Ordos Basin and on the southern margin of the Yili Basin. (2) The burnt rock aquifers and weathered bedrock aquifers in the concealed burnt areas are almost directly connected and integrated, exhibiting intimate hydraulic connections. (3) The measures to prevent and control the water hazard in burnt rocks principally include setting up coal pillars for water containment in burnt rock aquifers, draining the accumulated water in burnt rock aquifers, and cutting off water via grouting curtains. Grouting curtains allow for effectively mining coal resources overlain by burnt rock aquifers, removing the water disaster threat from burnt rocks, and preserving precious groundwater resources in burnt rock aquifers. (4) By pinpointing concealed burnt areas and drilling grouting holes, burnt rock aquifers in the concealed burnt areas can be isolated as several water-bearing bodies, thus cutting off the hydraulic connections inside and outside a grouting curtain. This approach can remove the threat that burned rock water poses to mining faces and preserve the water resources within burned rocks. (5) Water hazard control was conducted for burnt rock aquifers in the concealed burnt area where mining faces S1232 and S1233 of the Ningtiaota Coal Mine are located, reducing the water inflow to below 20 m³/h during coal mining and ensuring the safe coal mining of the mining faces. Furthermore, the water level decreased inside the grouting curtain and gradually increased outside the curtain, effectively preserving the water resources within burnt rocks.