煤层顶板巨厚基岩含水层空间富水性评价

Evaluation of spatial water enrichment of ultra-thick bedrock aquifer in coal seam roof

我国西部侏罗系煤田煤层顶板含水层垂向非均质性强,富水性差异大,使得导水裂隙带波及含水层深度不同时,工作面涌水量不同,水害威胁程度各不相同。为科学描述垂向不同深度含水层富水性对涌水的影响,将含水层简化为多层层状结构,由此概化出含水层空间富水结构表达模型。以彬长矿区亭南煤矿煤层顶板洛河组含水层为例,提出影响含水层空间富水性差异的含水系统、流动系统和地质构造3个方面,确定出含水层厚度、冲洗液消耗量、岩心采取率、中粗砂岩占比、地层埋深、水化学矿化度、褶皱构造7个主控因素,并采用AHP层次分析法确定各主控因素对富水性的影响权重,形成空间富水性评价模型。绘制含水层垂向各层状结构的主控因素专题图,并将其信息统一归一化处理,采用空间多源信息融合技术叠加,得出含水层上段、下段的富水性分区。评价结果表明,洛河组含水层上段可划分为“强、较强、中等”3个区,下段划分出“强、较强、中等、较弱、弱”5个区,对比表明上段富水性整体好于下段,并通过井田范围内不同层段含水层抽水试验成果进行拟合验证。由此得出,该富水性评价模型可充分反映含水层不同空间位置(平面、垂向)的富水性差异,对于导水裂隙带仅波及含水层部分层段条件下的顶板水害危险性评价有指导作用。

The aquifer of the coal seam roof in the Jurassic coalfield is highly heterogeneous in western China and has large differences in water richness.When the depth of the water-conducting fissure zone affects the aquifer is different,the amount of water inflow from the working face is different,and the threat of water damage is different.In order to scientifically describe the difference in the water inrush of the mine due to the difference of the vertical water yield property of the aquifer,the aquifer is simplified into a multi-layered structure,and an expression model for the spatial water rich structure of the aquifer is generalized.Taking Luohe Formation aquifer in the coal seam roof of the Tingnan coal mine in Binchang mining area as an example,the three main controlling factors affecting the water yield property of the aquifer were proposed:aquifer system,flow system and geological structure,the seven main controlling factors of aquifer thickness,flushing fluid consumption,core extraction rate,proportion of medium-coarse sandstone,stratum burial depth,water chemical salinity,and fold structure were determined,and the weights of each factor were determined by AHP analytic method.Finally,a mathematical model for evaluating the water-rich aquifer is formed.In this paper,the information of the main control factors of different vertical horizons is unified to normalized,using the multi-source information fusion technology to superimpose and establish a water yield property evaluation model for aquifer.The evaluation results show that the upper section of Luohe Formation aquifer can be divided into 3 zones:strong,relatively strong,and medium,and the lower sectioncan be divided into 5 zones:strong,relatively strong,medium,relatively weak,and weak.The comparison shows that the upper section has better water richness than the lower section,and it is verified by fitting the results through the pumping tests of aquifers in different intervals within the range of the well field.It can be concluded that the model can fully reflect the difference of water yield property of different spatial positions(horizontal and vertical)of the aquifer,and it can guide the evaluation of the water hazard risk of the roof under the condition that the water-flowing fractured zone only affects the partial layer of the aquifer.