Since the middle of 1980's, the Iongwall top-coal caving technique has developed rapidly in China. At present, it is one of the main approaches in the thick coal seam mining. This paper describes some mechanics problems of the caving technique, such as the damage and failure of the top-coal, the strata behaviors in the caving face, and the relation of the support and the surrounding rock. In order to employ the caving technique in a widespread scope, the problems such as the caving technique in the hard coal seam, the moving and running of the loose top-coal, and the upper floating of the gas etc. should be systematically studied.

通过模拟试验，系统地研究了综放开采顶煤移动与放出规律、煤岩分界线形状，不同采放比、不同放煤步距、不同煤岩粒径比条件下的顶煤回收率与含矸率等，在理论上提出了顶煤回收率的预测方法。

由于放煤口布置方向的差异，放矿椭球体理论的适用条件与低位放煤综放开采的放煤过程有本质差异，因此基于模拟试验、FLAC 计算、离散元模拟计算和现场观测，本文提出了散体介质流理论模型，揭示了低位综放开采中顶煤流动与放出的真实过程，并且成功地指导了现场放煤工艺与参数的确定。

There are a lot of uncertainties in the mining engineering, and they make a notable impact on the engineering. The uncertainties of the physical and mechanical properties of geotechnical mass, the surrounding rock stability, the nature condition, the equipment operation, the personnel and the external environment are proposed and described in this paper. The stochastic analysis should be widely used for considering the impacts of the uncertainty on the mining engineering. The economical risk analysis and the stochastic index system should also be set up in the mining engineering.