Abstract
During coal mining, the mechanical and deformation behavior of the overburden is affected by water and stress. Therefore, it is of great significance to study the mechanical behavior of the surrounding rock under the action of hydraulic coupling. For high-intensity mining with shallow coal seam and large mining and strong strata behavior in stope, the hydraulic support is often damaged. Based on basic experiments and physical similarity simulations, overburden fracture in shallow coal seam in western mining area under hydraulic coupling was studied. The results show that under the loading rate range of 0.5~5 mm/min, the compressive strength of sandstone increases with the loading rate. The faster the loading rate, the shorter the duration of the rock sample being loaded and damaged, and the fewer the acoustic emission events. The first weighting step of the main roof of the working face is 54 m, the periodic weighting step is 12.75~28 m, and the average periodic weighting step is 22 m. There are only caving zone and fractured zone in the overburden of working face; the height of caving zone and fractured zone is 60 m and 168 m, respectively. The strength of the saturated sample is significantly reduced. During the excavation of the working face, the temperature difference between the fracture and the overburden value is ≥1°C, which can be used as a threshold for judging the development range of overburden fracture in similar simulation experiments.
Highlights
IntroductionWith the shift of China coal resource strategy, a large number of modern large scale coal production bases represented by the Shendong mining area have emerged in Western China
Under the strong mining disturbance caused by high-intensity rapid mining to the migration of Geofluids overburden, the law of failure and migration of key stratum under the condition of shallow coal seam thin bedrock and large mining height was established
Overburden fractures in shallow coal seam and large mining height stope often occur during the slow mining speed period, which is similar to the failure characteristics of bedrock materials
Summary
With the shift of China coal resource strategy, a large number of modern large scale coal production bases represented by the Shendong mining area have emerged in Western China. With the aid of numerical simulation, monitoring, theoretical analysis, and similar simulation methods, the structural damage and fracture evolution of the overburden with shallow coal seam and large mining height in the western mining area have been studied, which monitor the ground subsidence of the working face and the characteristics of the roof pressure and analyze the dynamic changes of the overburden [4–8]. Through the compressive strength of the rock specimen taken under different loading conditions, theoretical analysis, and field monitoring data, the failure characteristics of the overburden in shallow coal seam with large mining height are investigated [16–24]. It is necessary to combine infrared monitoring methods and indoor similar physical simulations to study the evolution law of overburden fractures in shallow coal seams with the large mining heights
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