我国东部隐伏矿区煤层开采会引起新生界底部含水层（简称“底含”）地下水间接补给基岩面下砂岩含水层，这不仅会导致地面沉降，同时也增加了矿井排水量，排泄量的确定为矿井水害防治和沉降量的预测提供了一定的依据。以淮南煤田板集矿为例，通过对9煤顶板砂岩含水层疏放导致与上覆“底含”补给关系的分析，构建了“底含”数值模型，获得了其水文地质参数，采用水均衡原理计算并评价其排泄量。结果表明：研究区“底含”可划分为5个水文地质单元区块，渗透系数为0.433~0.824 m/d，弹性释水率为1.8×10⁻⁶~3.6×10⁻⁶ m⁻¹；在砂岩水疏放条件下，不同阶段“底含”排泄量约占疏放水总量的1/4，其来源主要为侧向补给和静储量消耗；因此，通过基岩风化带的注浆，封堵“底含”与煤层顶板之间的水力通道，是治理“底含”水补给砂岩水的有效措施。

The coal seam mining in the east of China will cause the groundwater of the bottom aquifer of the Cenozoic (referred to as “bottom aquifer”) to indirectly recharge the sandstone aquifer under the bedrock surface, which will not only lead to ground settlement, but also increase the mine drainage. The drainage amount is indeed a certain basis for the prevention and control of mine water damage and the prediction of settlement amount. Taking Banji Mine in Huainan Coalfield as an example, a numerical model of “bottom aquifer” was constructed by analyzing the relationship between the sandstone aquifer of 9^# coal roof and the overlying “bottom aquifer” recharge, its hydrogeological parameters were obtained, and its output was calculated and evaluated by water balance principle. The results show that the “bottom aquifer” in the study area can be divided into 5 hydrogeological unit blocks, the permeability coefficient is 0.433-0.824 m/d, the elastic water release rate is 1.8×10⁻⁶-3.6×10⁻⁶ m⁻¹. Under the condition of sandstone water drainage, the “bottom aquifer” discharge at different stages accounts for about 1/4 of the total drainage water, and its sources are mainly lateral recharge and static reserve consumption. Therefore, through the grouting of weathering zone of bedrock, the hydraulic channel between the bottom and the roof of coal seam is an effective measure to control the recharge of sandstone water from the bottom water.