Abstract
In order to solve the issues of uncertain overburden failure height and water loss at the Daliuta coal mine, the collapse characteristics of overburden and the development height of water-conducting fractured zone were studied by using physical modeling, FLAC 3D numerical simulation, and field observation, which were used to verify each other. In order to quantitatively analyze the distribution characteristics of fracture rate of overlying rock mass in goaf, the overburden collapse image was binarized. The results showed that: (1) the failure characteristics of overburden in goaf obtained by the three research methods were roughly consistent, and the reliability of the results was high. The overburden failure height of No. 5−2 coal with large mining height was 137.32–153 m, which was 20.8–23.2 times the mining height. (2) The repeated mining of No. 5−2 coal intensified the further failure of the disturbed rock mass in the No. 2−2 coal goaf. (3) In the horizontal direction of the goaf, the fracture rate of rock mass was distributed in the shape of “saddle”. In the longitudinal direction of the goaf, the rock mass fracture rate decreased in a logarithmic function with the increase of the height from the mining coal seam. Overall, the conclusions are of engineering significance for accurately adopting water resources protection mining technology and reducing mine water inrush disasters.
Highlights
Longwall mining is one of the most widely used methods in underground coal mining
Through the analysis of the revised empirical formula, it is found that the error between the predicted value of the new empirical formula and the height of water-conducting fractured zone obtained by similar simulation is 7.1%, and the error between the predicted value of the new empirical formula and the height of water-conducting fractured zone obtained by field observation is 3.6%
In order to solve the impact of shallow buried thick coal seam mining on water resources and environment at the Daliuta coal mine in the Shendong mining area, the characteristics of overburden collapse, movement, and deformation in multi coal seam mining were studied by using the methods of physical modeling, FLAC 3D numerical simulation and field observation, and derived the following conclusions: (1)
Summary
Longwall mining is one of the most widely used methods in underground coal mining. One of the most important advantages of this method is that it can mine coal resources efficiently and automatically. The coal seam overlying strata structure damage and fractures induced by mining lead to the changes of rock mechanics and hydraulic conditions, which is the main inducement of disasters caused by groundwater and gas flow [5]. It is of great significance to grasp the failure characteristics of overlying strata induced by mining and the evolution laws of mining fractures for coal mine water disaster prevention and protection of groundwater resources. The deformation and failure of overlying strata induced by longwall mining have been discussed by many researchers, and achieved fruitful results [6,7,8]. The failure of overburden strata induced by mining is the result of the combined effect of geological environment, mechanical environment, and engineering disturbance [9]. The previous mining datadata indicate thatthat the actual dedevelopment height water-conducting fracturedzone zoneininthis thisarea areaisis much much higher higher velopment height of of thethe water-conducting fractured than the the value value calculated calculated by by the the empirical empirical formula, formula, which which may may conduct conduct the the above above goaf goaf than water and aquifers, becoming the main water filling channel of the mine
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