导水裂隙带高度是实施保水采煤技术措施的一个重要参数，为获取厚松散层软弱覆岩下综放开采工作面导水裂隙带高度，以某矿11915工作面为例，综合运用井下钻孔注水漏失量观测、钻孔电视和数值模拟3种技术手段，对采空区上覆岩层导水裂隙带高度进行了探测。通过对井下施工的3个钻孔进行注水漏失量观测确定了开采前后的钻孔漏失量变化规律，结合钻孔电视观测的孔壁裂隙特征最终确定了导水裂隙带高度，并采用数值模拟分析了导水裂隙带发育规律。结果表明:厚煤层(6.65 m)，软弱覆岩、厚松散层(102 m)条件下综放开采的导水裂隙带高度为45.7~46.7 m，垮落带高度为16.1 m;裂采比为6.87~7.02，垮采比为2.42;数值模拟得到的导水裂隙带发育高度与现场实测结果一致，导水裂隙带发育经历发育、缓增、突增及稳定4个阶段，覆岩裂隙带以离层的形式向上发育，以铰接形式存在。钻孔电视能直接清晰的获取覆岩裂隙发育特征，是钻孔法探测导水裂隙带高度的最佳方法;井下钻孔漏失量法用于导水裂隙带高度观测是可靠的，但需要观测设备需要满足一定的封孔压力，封孔胶囊具有足够长度，并且需要改善胶囊与孔壁之间的接触状态。总体来讲，钻孔法观测导水裂隙带高度是目前最可靠的方法，但施工量大，成本较高;目前物探法应提高对覆岩完整性变化的探测敏感度，并多配合钻孔法的使用进行结果对照分析，获得物探结果最佳解释方法后再进行推广应用，降低导水裂隙带高度的探测成本。

Height of water-conducting zone is an important parameter for implementing water preserved mining techni- cal measures. In order to obtain the height of water-conducting zone in longwall top-coal mining caving mining face un- der thick alluvium and soft overburden,taking the 11915 working face of a mine as an example,three method were used to observe the height of water-conducting zone including borehole water leakage,borehole TV and numerical sim- ulation. Based on the observation of water leakage in three boreholes constructed underground,the variation law of wa- ter leakage was determined in boreholes before and after mining. The height of water-conducting zone was finally deter- mined according to the characteristics of borehole wall fissures observed by borehole TV,and the development law of water-conducting zone was analyzed by numerical simulation. The study results show that the height of water-conduc- ting zone is 45. 7-46. 7 m,the height of caving zone is 16. 1 m. The fracture-mining ratio is 6. 87-7. 02 and the ca- ving-mining ratio is 2. 42 in longwall top-coal mining under thick coal seam (6. 65 m),and soft rock stratum and thick alluvium (102 m). The height of water-conducting zone obtained by numerical simulation is consistent with the field measurement results. The development of water-conducting fracture zone has experienced four stages:development, slow increase,sudden increase and stability. Fractured zone develops upward in the form of separation layer and exists in articulated rock block type. The borehole TV can directly and clearly acquire the development characteristics of o- verburden fracture,and the best method to detect the height of water-conducting zone is borehole method. It is reliable to use borehole leakage method to observe the height of water-conducting zone. However,the observation equipment needs to satisfy a certain sealing pressure,and the sufficient length of sealing capsule. Also,the contact state between the capsule and the pore wall needs to be improved. In general,borehole method is the most reliable method to observe the height of water-conducting zone at present,but it needs a large amount of construction work and has a high cost. Currently,geophysical prospecting method should be improved on the sensitivity of detecting the change of overburden integrity,and the comparative analysis of results with borehole method should be conducted to obtain the best interpre- tation of geophysical results. Then it can be applied to reduce the detection cost of water-conducting zone height.