Characteristic of Development of the Fractured Zone in Mining under Medium Hard Overburden Using Fully-Mechanized Top-Coal Caving Method

For the prediction of the height of the fractured zone developed in mining with fully-mechanized top-coal caving system, the traditional calculation method, if used, generally yield a value with a comparatively large error. Based on mining condition of 6206 face at Wangzhuang Coal Mine in Luan mining area, a comprehensive study is made in the paper of the characteristics of the development of the fractured zone in the medium hard overlying strata under such full-seam mining conditions by taking various means, including field measurement and numerical and physical simulation. Through comparison with the field measurement data available and regression analysis, it can be seen that the height of the fractured zone developed in the medium hard overlying strata in mining with fully-mechanized top-coal caving system is directly proportional to the total mining thickness. In comparison with the result obtained with the use of empirical formula, the method used in the paper can better bring to light the occurrence of the intensive failure of overlying strata under such a mining condition. The research-derived achievement can serve as a basis for reference for the prediction of the height of fractured zone in mining under medium hard cover by using fully-mechanized top-coal caving method, and for decision making in mining under a water body.