Abstract
The movement and destruction of the hard roof in a stope is an important reason for the occurrence of strong ground pressure disasters at the working face. Considering Tongxin Coal Mine as the engineering background, the stress distribution law of the surrounding rock and the overburden rock damage characteristics of a large-mining-height working face under the hard roof were investigated. To solve the problem whereby the stope’s hard roof is difficult to collapse, the hard rock key stratum of the roof was hydraulically fractured to weaken the mechanical properties of the roof rock stratum. Additionally, microseismic monitoring technology was used to monitor the cracking effect of the rock stratum. The theoretical calculation and numerical simulation results reveal that, after hydraulic fracturing, a crack with a more consistent trend formed inside the hard rock stratum and a large area of the rock stratum was damaged. According to the monitoring results of the stope stress after hydraulic fracturing, the law governing the occurrence of the leading bearing pressure was in effect. In contrast, the influence range and peak strength of the leading bearing pressure were considerably reduced at the working face after hydraulic fracturing. After performing hydraulic fracturing on the roof of the working face, the bearing pressure of the working face can satisfy the production requirements better. Finally, the results obtained through this study can be used as a reference for determining the width of coal pillars under similar mining conditions.
Highlights
In China, coal is a primary energy source. e proven coal reserves amount to 1.34 trillion tons, 44% of which are buried in 6–20 m super-thick coal seams
With the increase of the mining height, the overburden movement and stress concentration effects caused by coal seam mining are increasingly becoming obvious and are accompanied by several accidents, such as roof collapse, coal-seam gas outburst, and rock burst [6,7,8], which pose severe threats to mining safety
To effectively evaluate the effect of hydraulic fracturing, the real-time monitoring of the fracturing process was combined with microseismic monitoring technology. is paper proposes a method for preventing strong mine pressure disasters occurring in a stope with a hard roof. e results obtained by this study can be useful as a reference in the development of hydraulic fracturing technology for the fracturing and weakening of hard rock stratums
Summary
In China, coal is a primary energy source. e proven coal reserves amount to 1.34 trillion tons, 44% of which are buried in 6–20 m super-thick coal seams. Focusing on abutment pressure distribution in the super-thick alluvia of coal mines with strong rock bursts, Zhu et al [15] explored the abutment pressure load transfer mechanism based on the key stratum theory, surveyed Xinjulong Coal Mine using stress and microseismic monitoring, and verified model rationality. The analysis of the correlation between the change of the lead abutment pressure and roof movement and the proposal of appropriate technical measures against the characteristics of largemining-height coal seam pressure were dramatic and the impact range was large [18,19,20,21,22]. A numerical simulation method was used to investigate the stress distribution law of the surrounding rock in the stope under the hard roof condition. To effectively evaluate the effect of hydraulic fracturing, the real-time monitoring of the fracturing process was combined with microseismic monitoring technology. is paper proposes a method for preventing strong mine pressure disasters occurring in a stope with a hard roof. e results obtained by this study can be useful as a reference in the development of hydraulic fracturing technology for the fracturing and weakening of hard rock stratums
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
