基于导水裂缝带的地下水动态模拟及预测

Simulation and prediction on groundwater system dynamics in water flowing fractured zone

为研究煤炭地下气化过程中形成的导水裂缝带对地下水流场的影响,以FLAC 3D模型模拟导水裂缝带发育结果为基础,利用Visual Modflow构建分时段气化区地下水流数值模型来模拟气化过程中地下水渗流场的变化特征,并预测矿井涌水量。结果表明:上含水系统地下水渗流场特征在点火之后至燃烧结束变化不甚明显,气化过程未对上含水系统产生影响;顶板隔水层被导通的初始阶段,导通区域会形成明显的"反降落漏斗",导通沟通了气化层与顶板含水层之间的水力联系,随着时间的推移形成与顶板含水层相似的地下水渗流场特征。三维数值模拟法预测矿井涌水量为164m^3/d,可以作为矿井排水方案的设计依据。

In order to study the influence of water flowing fractured zone formed by underground coal gasification on groundwater flow field, basing upon development results of water flowing fractured zone simulated by FLAC3D, the author used Visual Modflow establishing a multi-scenario 3D numerical model of groundwater flow to simulate variation characteristics of groundwater flow field in gasification process and predicte mine inflow. The results showed that the characteristics of the groundwater seepage field in the upper aquifer system had no obvious change from ignition to combustion ending, process of gasification had no effluence to upper aquifer system, con- ducting regime formed obviously inverse falling funnel in the initial phase of conducting the roof aquifuge which leading to hydraulic connection between gasification layer and roof aquifer, as time went on, the roof aquicluge formed the characteristics of groundwater flow field that similar to the roof aquifer. The three dimensions numerical model predicted mine water inflow was 164 m^3/d, which could be used for design consideration of mine drainage scheme.