Abstract
As the mining depth increases, under the influence of high ground stress, the surrounding rock of deep mine roadways shows soft rock characteristics. Under the influence of mining disturbance at the working face, large deformation of the roadway has occurred. To control the large deformation of the roadway, many mines have adopted the form of combined support, which has continuously increased the support strength and achieved a certain effect. However, since the stress environment of the surrounding rock of the roadway has not been changed, large deformation of the roadway still occurs in many cases. Based on the theoretical basis of academician Manchao He’s “short cantilever beam by roof cutting,” this paper puts forward the plan of “presplitting blasting + combined support” to control the large deformation of the deep mine roadways. Without changing the original support conditions of the roadway, presplitting blasting the roof strata of the roadway, by cutting off the mechanical connection of the roof strata between the roadway and gob, improves the stress distribution of the roadway to control the large deformation. Through field tests, the results show that after presplitting blasting the roadway roof, the roadway roof subsidence is reduced by 47.9%, the ribs displacement is reduced by 45.7%, and the floor heave volume is reduced by 50.8%. The effect is significant.
Highlights
China’s coal resources buried below 1000 m are 2.95 trillion tons, accounting for 53% of the total coal resources [1, 2]
There are more than 100 coal mines in China with a depth of more than 600 m, 38 coal mines with a depth of more than 1000 m, and the deepest is more than 1500 m [3, 4]. e existing research results show that with the increase in mining depth, the vertical stress continues to increase. e tectonic stress increases forming a high stress condition of “high vertical stress and high tectonic stress” at a large buried depth, which leads to a series of problems such as large deformation, roof fall, rib spalling, and floor heave [5,6,7]
Based on the engineering background of the 3307 ventilation roadway of Xingcun Coal Mine, this paper studies the large deformation of the deep mine roadway through theoretical analysis, numerical simulation, and on-site monitoring. e main conclusions are as follows: (1) Using Flac3d software, the two working conditions of presplitting blasting and non-presplitting blasting of the roadway roof strata were numerically simulated. e results showed that (a) After presplitting blasting the roadway roof strata, a pressure relief zone will be formed within 30 m of the blasting side of the working face and the surrounding rock stress reduced significantly
Summary
China’s coal resources buried below 1000 m are 2.95 trillion tons, accounting for 53% of the total coal resources [1, 2]. How to effectively control the large deformation of deep mine roadways has become a problem of the coal industry [14,15,16]. A single rigid or flexible support method cannot effectively control the large deformation of the deep mine roadway. With the increase in mining depth, it has become more and more difficult to maintain the stability of the surrounding rock of deep mine roadways solely by supporting methods. To ensure the safety of deep mine roadways, many coal mines can only continuously increase the support strength and sometimes need to use passive methods such as roof ripping, rib expansion, and undercutting to ensure the section size of the roadway, which seriously restricts the transformation of coal mine enterprises to high production and efficiency [25,26,27]. Based on the theory of “short cantilever beam by roof cutting” proposed by academician Manchao He, this paper proposes a “presplitting blasting + combined support” scheme to control the large deformation of the deep mine roadway [28,29,30]. is paper takes the Xingcun Coal Mine of Shandong Tianan Mining Co., Ltd. as the engineering background to conduct research
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