Abstract

In order to reveal the failure mechanism of the deep roadway under mining-induced pressure in coal mine, the boundary equations for the plastic zone around the deep roadway were deduced, and then the evolution laws for morphology of the plastic zone and the relationship between the morphological indexes and the stability of surrounding rock were discussed. The results show that, for the deep roadway, the effect of mining on the plastic zone is more sensitive than that on the shallow one. Even if the changes of mining influence are small, they may also cause extremely serious plastic failure of surrounding rock masses, leading to the sudden instability of the roadway. When the plastic wings of the plastic zone are approximately perpendicular to the roof, floor, or sidewall, the large deformation and failure of the deep roadway are very likely to occur. Compared with the index of the uniformity coefficient, the irregular shape coefficient can be used to better characterize the differences in the plastic zone morphology. Finally, a case study was provided to apply the principles for the formation and extension of a butterfly-shaped plastic zone.

Highlights

  • With the increasing shortage of coal resources in shallow depth, the mining depth of coal mine in China is increasing at a speed of 10–25 m per year

  • Deep coal mining is confronted with some complicated problems such as large deformation, rockbursts, and water hazards [5,6,7,8]

  • In view of the nonlinear problems of large deformation occurring in a deep soft rock roadway, He [17] adopted the material point method (MPM) to simulate the large deformation and failure process of deep rocks

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Summary

Introduction

With the increasing shortage of coal resources in shallow depth, the mining depth of coal mine in China is increasing at a speed of 10–25 m per year. Large deformation and failure of deep roadways are related to high stress and weak rock masses and closely associated with the mining-induced pressure (the side and front abutment pressure); the influence of mining is sometimes a nonignorable factor [29, 30], whereas limited research studies [31, 32] have been carried out on the damage and failure of deep roadways subjected to mininginduced pressure. Erefore, the distribution and evolution of the plastic zone around the deep roadway under the secondary stress field is key to investigate its failure mechanism. (4) Influenced by high geostress, repeated mining activities, and geological structures, the deformation of the roadway surrounding rock appears significantly asymmetry, which hinders the utilization of the roadway (Figure 1(d)). Evolutionary Laws of Morphology for Plastic Zone around Deep Roadways under Mining-Induced Pressure

Evolution Equation for Boundary of Mining-Induced Plastic Zone
Profile of y 0 the roadway
Field Validation
Conclusions
Full Text
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