Abstract

Noncoal pillar mining with automatic formation of a roadway is a new coal mining method that is tailored to improve the coal resource recovery rate and reduce the investment in roadway tunneling. Using this proposed method, a reuse entry is formed by roof cutting instead of tunneling. In this paper, the S1201-II working face of the Ningtiaota Coal Mine was used as a case study. The stress distribution of surrounding rock and the roof deformation characteristics of the reused entry during the mining process of the second working face were studied through FLAC3D numerical simulations combined with field measurements. The results indicate that the zone close to the reused entry led to higher stress in advance. If this stress is superimposed with the lateral pressure of the adjacent mined working face, it will be more difficult to maintain the reused entry. In the engineering case study described here, the reused entry created a stress increase zone and a severe deformation zone in the range of 0–80 m in front of the working face, and its range was approximately 37.5% larger than an ordinary entry. The stress peak in the stress increase zone increased by approximately 34.7% over that of an ordinary entry. The maximum amount of deformation within the severe deformation zone increased by 94.4% over that of an ordinary entry. To properly control the surrounding rock stress and deformation of the reused entry, a dynamic pressure bearing support in front of the working face with adaptability to the large roof deformation and high support strength is proposed here. Field application results showed that the final roof deformation with the dynamic pressure bearing support can be satisfactorily controlled within 110∼130 mm. These findings can provide a reference for researchers and field engineering technicians when engaging in the support work of reused entry.

Highlights

  • Longwall mining is a mining method that has been widely used around the globe, which has the advantages of safety, high efficiency, and high mechanization [1, 2]

  • Surrounding rock stress distribution and roof deformation characteristics in the second service stage of reused entry were investigated through FLAC3D numerical simulation combined with the site measurement. e roof control method that fits the mine pressure behavior of the reused entry was proposed . e results of this research can instruct scientific researchers and site engineering technicians to provide site entry support properly and are of great significance in improving the theoretical system and the key technology system of noncoal pillar mining with the automatic formation of a roadway

  • Ningtiaota Coal Mine is located in Shenmu county, Shannxi province, China. e S1201-II working face is the test working face for noncoal pillar mining with the automatic formation of a roadway. e tendency length of the test working face is 280 m, and the strike length is 2344 m

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Summary

Introduction

Longwall mining is a mining method that has been widely used around the globe, which has the advantages of safety, high efficiency, and high mechanization [1, 2] This mining method generally requires two advance tunnels and a coal pillar with a width of 5–30 m reserved between every two working faces [3]. This mining method has led to a huge waste of coal resources, which in turn places the sustainable development and utilization of coal resources in an unfavorable position [4]. To avoid this waste of resources and large investment in tunneling as mentioned above, Prof He Manchao proposed a method involving noncoal pillar mining with the automatic formation of a roadway [10]. Surrounding rock stress distribution and roof deformation characteristics in the second service stage of reused entry were investigated through FLAC3D numerical simulation combined with the site measurement. e roof control method that fits the mine pressure behavior of the reused entry was proposed . e results of this research can instruct scientific researchers and site engineering technicians to provide site entry support properly and are of great significance in improving the theoretical system and the key technology system of noncoal pillar mining with the automatic formation of a roadway

Geological Background and Site Details
Dramatic Effect of Roof Structure on a Reused Entry
Mine Pressure Behavior Characteristics of the Reused Entry
Control Method and Field Test
Test Results and Discussion
Conclusions
Full Text
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