浅埋煤层顶板突水是由于导水裂隙带贯穿隔水层而引起的，随着煤层群的下行开采，土层与基岩层的协同隔水机理亟待明确。为了分析隔水土层在煤层群下行开采工程背景下的破坏机理，以便准确预测煤矿顶板突水问题，以陕北神府矿区韩家湾煤矿2⁻²、3⁻¹和4⁻²煤下行开采为研究背景，通过原位钻孔取心试验得出不同埋深的隔水土层性质的差异；通过建立上层位隔水土层渗透扩展力学模型来描述裂隙发育形态；采用土−岩复合隔水层力学模型，在“给定变形”条件下计算下层位隔水土层处于整体稳定状态时的力学判据。研究表明，隔水土层根据其性质不同可以分为上层位隔水土层和下层位隔水土层；通过比较总载荷与上层位隔水土层抗拉强度的大小，当总载荷小于等于上层位隔水土层抗拉强度时裂隙不再向下发育从而得出裂隙发育长度；在“给定变形”条件下，当下层位隔水土层长边中部位置处产生的拉应力小于或等于拉伸强度阈值时，下层位隔水土层整体结构处于稳定状态，不会产生拉伸破坏；根据韩家湾煤矿地质情况进行数值模拟，模拟结果与理论分析结果相吻合。研究可为相似地质条件下顶板突水预测提供参考。

The roof water inrush of shallow buried coal seam is caused by the water flowing fractured zone through the aquifuge. With the downward mining of coal seam group, the mechanism of synergistic water isolation between soil layer and bedrock layer needs to be clarified. In order to analyze the failure mechanism of aquiclude under the background of downward mining of coal seam group, so as to accurately predict the water inrush problem of coal mine roof, taking the downward mining of 2⁻², 3⁻¹ and 4⁻² coal seams in Han Jiawan Coal Mine of Shenfu Mining Area in Northern Shaanxi as the research background, the differences in the properties of aquiclude at different depths were obtained by in-situ borehole coring experiments. The development form of cracks is described by establishing the mechanical model of seepage expansion of upper aquifuge soil layer. Using the mechanical model of soil-rock composite aquiclude, the mechanical criterion of the lower aquiclude in the overall stable state is calculated under the condition of ‘given deformation’. The research shows that the aquiclude can be divided into upper aquiclude and lower aquiclude according to its different properties. By comparing the total load with the tensile strength of the upper aquifuge, when the total load is less than or equal to the tensile strength of the upper aquifuge, the crack no longer develops downward to obtain the crack development length. Under the condition of ‘given deformation’, when the tensile stress generated at the middle position of the long side of the aquiclude is less than or equal to the tensile strength threshold, the overall structure of the lower aquiclude is in a stable state, and no tensile failure will occur. According to the geological conditions of Han Jiawan coal mine, the numerical simulation results are consistent with the theoretical analysis results. The research can provide reference for roof water inrush prediction under similar geological conditions.