随着我国华北型煤田开采深度逐年增加，大部分矿井已面临由上组煤转向深部及下组煤开采阶段，奥陶纪灰岩岩溶水害威胁呈上升趋势，底板突水危险逐年增加，而目前规范和规程中的底板突水系数法虽然应用较广泛，但并未充分考虑到奥灰顶部实际阻水能力，其评价方法存在一定的局限性。在现有奥灰顶部地质及水文地质条件认识的基础上，提出了部分矿区奥灰顶部存在阻水性能较好的风化充填带可作为隔水层利用的理念，将煤系隔水层厚度、风化充填带厚度、注浆改造段厚度和底板扰动破坏深度视为底板突水系数判别式的影响因素，建立了改造奥灰顶部岩层段厚度的判别准则，论述了底板破坏深度在判别准则中的重要性，并以韩城矿区桑树坪煤矿11号煤层3105工作面开采为典型案例，通过构建的17组数值模拟方案，分析得出了煤层开采深度对底板扰动破坏深度影响最大、开采厚度最小、开采宽度则存在尺寸效应等结论;同时将模拟数据与全国相似矿区实测样本结合，给出了采深、采宽和采高3因素影响的预测模型，并对其进行了验算和适用性分析，结果表明新模型拟合方程的误差均值、百分比、方差和均方差均优于统计公式，具有预测精度高、误差小、适用性广等特点，基本满足工程实际需要。其研究成果可用于奥灰顶部含水段的注浆改造实际工程中，对深部下组煤安全带压开采提供有利的技术保障。

As the mining depth of North China coal field increases year by year,most of the mines have been faced with the stage of coal mining from the upper coal group to the deep and lower coal groups. The threat of karst water disaster in the Ordovician limestone is on the rise,and the floor water inrush hazard increases year by year. However, although the floor water inrush coefficient method in the current code and regulation is widely used,it does not fully take into account the actual water blocking capacity of the Ordovician limestone top,and its evaluation method has some limitations. Therefore,based on the existing understanding of the geological and hydrogeological conditions on the top of Ordovician limestone,this paper puts forward the idea that the weathered backfill zone with good water resist- ance at the top of Ordovician limestone in some mining areas can be used as the aquifuge. The thickness of coal meas- ure aquifuge,the thickness of weathered backfill zone,the thickness of grouting reconstruction section and the destruc- tion depth of bottom plate disturbance are considered as the influencing factors of the discriminant of bottom plate wa- ter inrush coefficient,and the criteria for judging the thickness of the reconstruction of the strata section at the top of Ordovician limestone are established. The importance of the failure depth of the bottom plate in the discriminant crite- rion is discussed. And taking the mining of No. 11 coal seam in Sangshuping Coal Mine of Hancheng Mining Area as a typical case,through the 17 sets of numerical simulation schemes constructed,it is analyzed and concluded that the depth of coal seam mining has the greatest influence on the destruction depth of bottom plate disturbance,the mining thickness is the smallest,and the mining width has size effect;at the same time,combining the simulated data with the measured samples of similar mining areas in China,the prediction model of the influence of mining depth, mining width and mining height is given,and the verification calculation and applicability analysis are carried out. The results show that the error mean value,the percentage,variance and mean square deviation of the new model fitting equation are superior to the statistical formula,and have the characteristics of high prediction accuracy,small error and wide ap- plicability,which basically meets the practical needs of engineering. The research results can be used in the practical project of grouting in the water-bearing section of the Ordovician limestone top,and provide favorable technical guaran- tee for seat belt pressure mining of deep lower group coal.