再论煤层顶板涌(突)水危险性预测评价的“三图-双预测法”

Further research on “three maps-two predictions”method for prediction on coal seam roof water bursting risk

针对煤层直接顶板隔水层缺失或沉积较薄、且上覆充水含水层富水性较弱条件下的顶板水害评价预测,在"三图-双预测法"理论与方法指导下,分别从顶板冒裂程度和含水层富水性强度2个方面入手再次讨论了顶板含水层涌(突)水危险性评价方法。顶板冒裂程度以导水裂缝带扰动破坏上覆含水层距离作为评价指标;含水层富水性评价方法则进一步提升,以富水性指数法为依托,一方面充分挖掘地质和水文地质勘查数据中与含水层富水性相关的信息,包括渗透系数、砂岩厚度、冲洗液消耗量、岩芯采取率和脆塑性岩厚度比等,并将其作为主控地质因素,另一方面将数量有限的单位涌水量作为含水层富水性的实测指标对富水性指数法的评价结果进行校正,解决了在水文地质勘查程度较低情况下含水层富水性合理准确评价与分区难题。在此基础上运用Visual Modflow的DRN边界子模块对天然状态下和采取防治水措施状态下工作面的涌水量进行了动态预测。最后以台格庙矿区为例,说明了特殊水文地质结构条件下煤层顶板涌(突)水危险性评价和涌水量预测方法的具体实施步骤。

In terms of the conditions of missed or thin coal seam direct roof impermeable layer and poor water yield capacity of roof aquifer,on the basis of ＂three maps-two predictions＂method,the roof aquifer water bursting risk evaluation method is further investigated from two aspects,one is roof caving and fractured degree,the other is roof aquifer water yield capacity. The roof caving and fractured degree is represented by the height of water-conducting zone. While the aquifer water yield capacity evaluation method is largely promoted on the theoretical basis of water-richness index method. On the one hand,the geology and hydrogeology investigation information,such as permeability coefficient,sandstone thickness,flushing fluid consumption,core recovery percentage and the thickness ratio of friable rocks to plastic rocks are used and regarded as the main controlling factors of water yield capacity. On the other hand,the fewmeasured specific water yields are used to calibrate the evaluation result of the water-richness index method. The new method works out the problem of roof aquifer water yield capacity evaluation on the condition of low hydrogeology investigation. In addition,the mine inflow of the mining workface is estimated on natural and artificial interference conditions by the DRN boundary condition of the Visual Modflow software. Finally,the Taigemiao coal field is taken as an example to show the detail operation steps of roof aquifer water bursting risk evaluation and mine inflow prediction.