覆岩离层注浆减沉技术是保护矿区地表建(构)筑物的重要手段之一，其中注浆层位选择与其下方隔浆层完整性是决定地表减沉效果的关键因素。采用理论分析、工程试验以及现场监测等手段，对覆岩离层注浆层位判别及其下方隔浆层稳定性进行了研究。通过理论分析方法对覆岩离层注浆过程中的隔浆层变形特征进行了研究，建立了基于弹性地基梁理论的隔浆层挠曲线方程，并根据岩层破坏程度，分区计算了隔浆层下方岩体的弹性地基系数，得到了注浆压力作用下隔浆层的最大弯曲下沉值；基于岩层破坏条件给出隔浆层稳定性分析方法，计算了注浆前后隔浆层下方自由空间的高度，并依据隔浆层最大弯曲下沉值与其下方自由空间的关系，对固支梁及弹性地基梁状态下的隔浆层完整性进行了判别；在此基础上，综合考虑注浆地层条件及隔浆层稳定性，提出了一种新的覆岩离层注浆层位判别方法。该方法通过计算导水裂隙带及各关键层高度确定潜在注浆层位，然后依据隔浆层完整性分析对各潜在注浆层位的可行性进行判别，最后引入安全系数对其稳定性进行评价。以某矿11090工作面为工程应用实例，依据该判别方法确定了合理注浆层位，在距煤层139.1 m处成功实施覆岩离层注浆充填，结合地表实测数据及地表下沉预计结果，该工作面实施注浆后，地表最大下沉值为230 mm，下沉系数为0.12，减沉率达到77.6%。附近民房的最大倾斜值约为0.8 mm/m，水平变形值为0.7 mm/m，有效保护了矿区地表村庄民房，同时保障了井下采掘工作的正常进行，验证了注浆层位判别方法的合理性，为覆岩离层注浆层位设计及矿区地表沉陷控制提供了参考。

The technology of bed separation grouting subsidence reduction is one of the important means of protecting surface buildings and infrastructures in mining areas, the selection of the grouting layer and the integrity of the slurry-resisting overburden below are the key factors affecting the effectiveness of subsidence reduction. By means of theoretical analysis, on-site test and field monitoring, the determination of grouting layer in separation grouting and the stability of the Slurry-resisting overburden are studied. The theoretical analysis method was used to study the deformation characteristics of the slurry-resisting overburden in the separation grouting technique. A deflection curve equation for the slurry-resisting overburden based on the elastic foundation beam theory was established, and the elastic foundation coefficient of the rock mass below the slurry-resisting overburden was calculated according to the degree of rock damage zoning. The maximum bending subsidence value of the grout slurry-resisting overburden under grouting pressure was obtained; based on the failure condition of strata, the stability analysis method of the slurry-resisting overburden is given, the height of the free space below the slurry-resisting overburden before and after grouting was calculated, and based on the relationship between the maximum bending subsidence value of slurry-resisting overburden and the free space below, the integrity of the slurry-resisting overburden in the state of fixed-support beams and elastic foundation beams was judged; on this basis, a new discrimination method of the grouting layer is proposed by considering the grouting stratigraphic conditions and the stability of the slurry-resisting overburden. This discrimination determines the potential grouting layers by calculating the height of the water conducting fracture zone and each key strata, and then distinguishes the feasibility of each potential grouting layer according to the integrity analysis of the slurry-resisting overburden, the safety factor is introduced to evaluate its stability. Taking the 11090 working face as an engineering application example, the reasonable grouting layer was determined through the discrimination method, and the overburden bed separation grouting is successfully implemented at 139.1 m from the coal seam. Combined with the measured data from the surface observation station and the estimated surface subsidence, the maximum surface subsidence value after grouting was 230 mm, the subsidence coefficient was 0.12, and the subsidence reduction rate reached 77.6%. The maximum inclination value of nearby residential houses is about 0.8 mm/m, and the horizontal deformation value is 0.7 mm/m, effectively protecting the surface buildings and infrastructures, while ensuring the normal progress of underground mining, verifying the rationality of the grouting layer discrimination method, and providing reference for the design of separation grouting layer and the control of surface subsidence in the mining area.