煤炭资源的需求与日俱增，华北型煤田的浅部和上组煤已经被开采的日渐匮乏，其深部和下组煤的开采在许多煤矿已经成为发展的必然选择。开采下组煤的难题，除了顶部采空区的透水灾害外，煤层底板突水才是最严重的症结所在。为了解决这个难题，一般采用的方法是进行工作面或者区域注浆，加固底板的阻水能力；或人工疏导降压，对于奥灰顶部风化壳的天然阻水能力并没有给予重视并利用。事实上，古地壳运动后奥灰顶界面经历了长时间的风化剥蚀和侵蚀，形成了一些溶蚀孔洞和裂隙，但经过众多因素的影响，这些岩溶空间被黏土等弱透水性物质充填，并经过上覆岩层的压实作用，形成了具有天然阻水能力的岩层。因此，对其进行的研究意义重大。 本文以陕西韩城桑树坪煤矿为工程背景，针对奥灰顶部岩层展开阻水能力分析与预测研究，主要内容如下： 1、 分析了矿区的基础地质、水文地质资料和区域地下水、井田下组煤底板主要含水层（奥陶系灰岩含水层）的含、阻水条件，认为区域内奥陶系顶部灰岩可以作为相对阻水层，并定义了本文的研究段厚度。 2、 结合地质背景资料和构造发育理论，对奥陶系顶部进行综合研究，得出了奥灰顶部阻水能力的指标体系，包括岩性组合及结构、地质构造、钻孔岩芯采取率、冲洗液消耗量、充填压实程度和阻水厚度指标。 3、 运用ArcGIS软件与AHP法结合，通过确定阻水性指标，绘制各指标专题图，计算各指标权重并进行专题图叠加，建立反映各种指标因素对其产生的叠加影响的评价模型，这个模型所得出的计算值能更直观反映出奥灰顶部的阻水能力。 4、 运用分级地图上常用的自然分级法，结合矿井生产实践，对其进行分级得出相应的阈值，并得到了研究区阻水能力分区，其评价结果与其构造分布呈一定相关性。通过地质构造跟钻孔数据对所得的阻水能力分区进行工程验证，效果比较理想。

To continue to promote economic progress, and with the growing demand for coal resources, the shallow and deep of North China coal have been mined on a group of increasingly scarce, the deep coal mining have become the inevitable choice of development to many coal mines. In addition to the flooding disaster at the top of the mined-out area, water bursting is the most serious problem in the deep coal mining. The general approach to solve this problem is to grout Face and area, reinforce bottom impermeability, and grooming reduced water pressure artificially. The natural impermeability of the top of Ordovician limestone hadn’t given great attention and been used. In fact, after the ancient crustal movement, Ordovician limestone top interface experienced a long period of weathering and erosion, formed some corrosion holes and cracks, but after a number of factors affecting, these karst space is filled with clay and other low permeability material, and after overburden compaction, this becomes rock which has a natural water-blocking ability. Therefore, understanding the performance of North China coal strata water blocking for solving coal mining group has an important significance. The evaluation of impermeability in Ordovician limestone top is set in Sangshuping coal mine of Hancheng Anthracite Mining Group, results are as follows: (1) Analyze the Geological data base and Hydrogeological data of the Mine, hydrogeology condition and impermeability of Ordovician limestone aquifer，Comprehensive research consider that the top of Ordovician limestone can be seen as relative aquifuge, meanwhile define the thickness of layer in this dissertation. (2) Comprehensive research about Geological background and geologic structure export a indicator system for evaluation of impermeability in the top of Ordovician limestone, including lithologic and structural, geological structure, drill core taken rate, fluid consumption，the degree of compaction and the thickness. (3) Based on Analytic Hierarchy Process(AHP) by using ArcGIS program, by defining resistance index, drawing profiles of index, evaluating weight of factors and superposing profiles, and then build evaluation system which reflect the consequences of factors. (4) Based on production practice by using natural breaks classification, evaluated the break points and divided impermeability regions which had an association with distribution structure. The evaluation result is satisfactory by testing with geological structures data and measured data of hole-drilling.