柠条塔井田南翼隐伏火烧区特征及富水性评价

Characteristics and water abundance evaluation of concealed burning area in southern of Ningtiaota Coal Mine

煤层火烧区在我国西部煤炭区大面积分布,当火烧区内烧变岩含水层与其他含水层有较强水力联系时,会对煤矿安全开采构成严重威胁。以柠条塔井田南翼东南角1^(-2)上煤隐伏火烧区为例,基于以往各类水文地质资料,恢复了保德组沉积前古地形并分析了隐伏火烧区地层特征和补径排水文地质特征;采用因子分析法提取了反映隐伏火烧区含水层的富水性特征因子,通过GIS空间叠加方式得到隐伏火烧区复合含水层富水性综合分区。结果表明:1^(-2)上煤层自燃时代为早白垩世末至上新世期间,古冲沟的发育为煤层的自燃和烧变岩的形成提供了有利条件;隐伏火烧区内烧变岩含水层和风化基岩含水层基本连为一体,构成统一含水层;1^(-2)上煤覆岩组合关系可分为3类:即烧变岩-风化基岩、煤层-烧变岩-风化基岩、煤层-烧变岩-正常基岩-风化基岩组合;强富水性区主要分布于火烧区的北部与西部小范围内,中等富水性区沿北西-南东向呈带状分布于火烧区内,隐伏火烧区东部及北部区域富水性相对较弱,弱富水性区域均分布于隐伏火烧区外。与井下探放水钻孔涌水量对比,该富水性分区评价结果与实际吻合较好。

Coal seam fire area is widely distributed in western coal area of China. When there is a strong hydraulic connection between the burned rock aquifer and other aquifers in the coal seam fire area, it will pose a serious threat to the safe mining of coal mine. Taking the 1^(-2)upper coal concealed burning area in the southeast corner of Ningtiaota Coal Mine as an example, based on various past hydro-geological data, the ancient topography before the deposition of Baode Formation was restored, and the stratum characteristics of the concealed fire area and the geological characteristics of the compensation channel drainage were analyzed. The factor analysis method is used to extract the characteristic factors reflecting the water abundance of burnt rock and weathered bedrock aquifer, and the comprehensive water-rich zone of burnt rock and weathered bedrock aquifer is obtained through GIS superposition method. The results show: the 1^(-2)upper coal seam burned from the early Cretaceous to the Pliocene,the development of ancient gullies provides favorable conditions for the formation of spontaneous combustion and burning metamorphic rocks in coal seams;the burnt rock aquifer and weathered bedrock aquifer in the concealed burning area are basically connected together to form a unified aquifer;the overburden rock combination relationship on 1^(-2)upper coal concealed burning area can be divided into three types, namely burnt rock-weathered bedrock combination, coal seam-burnt rock-weathered bedrock combination, coal seam-burnt rock-normal bedrock-weathered bedrock combination. Strong water abundance areas are mainly distributed in a small area in the north and west of the burning area, the medium water abundance areas are distributed in the burning area in a belt along the northwest-southeast direction;the eastern and northern areas of the concealed burning area are relatively weak in water abundance;the weak water abundance areas are distributed outside concealed burning area. Compared with the water inflow of underground water exploration and release boreholes, the evaluation of water abundance is in good agreement with the practice.