Abstract
The traditional gob-side entry-retaining mining method has problems such as difficulty in roof collapse and large deformation of the entry, which may affect the safety of mine production. In this study, we introduced a bidirectional blasting technology (BBT) to make the roof collapse smoothly and to improve the traditional gob-side entry-retaining mining method. A theoretical model of the BBT was established and the stress propagation of the BBT was analyzed by numerical simulation. The gob-side entry-retaining mining method was then applied in a composite sandstone roof condition. Compared with ordinary blasting, the concentrated stress and directional cracks can be generated in the set direction after using the BBT technology. Field monitoring data suggested that the deformation of the retained entry met the requirements of mining, verifying the effectiveness of the proposed technology for composite sandstone roof. The results of the study have an important significance in solving the high pressure and large deformation problems in the coal mine roadway and saving coal resources, which also provided a reference for similar geotechnical mines.
Highlights
In recent decades, China has achieved great development
The numerical simulation models of ordinary blasting and energy-gathering blasting were established, and the distribution law of explosion stress wave under two blasting modes was analyzed under the composite sandstone roof
A uniform stress wave of blasting stress is generated around the blast hole, forming circular damage and destruction
Summary
These achievements need the support of a large amount of energy. With the increase in coal mining, the problems of underground engineering have become increasingly prominent. The traditional coal mining method requires coal pillars, causing much coal loss, which are becoming increasingly prominent [1,2]. Setting coal pillars between working faces leads to a great waste of resources, and at the same time, it is easy to cause rockburst, gob fire, gas accumulation, and other disasters [3,4,5,6]. In order to solve the above problems, the gob-side entry-retaining technology has been proposed, which can increase the coal recovery rate and reduce the amount of roadway driving and realize Y-shaped ventilation. It is beneficial to improve the safety and economic benefits of the coal mine [7,8,9,10,11]
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