Law of coal caving behind the flexible shield support in pseudo-inclined working face.

Qinjian Zhan,Niaz Muhammad Shahani,Shengqiang Li,Zhicheng Xue,Oluwole Daniel Makinde

doi:10.1371/journal.pone.0261355

Qinjian Zhan, Niaz Muhammad Shahani + Show 3 more

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https://doi.org/10.1371/journal.pone.0261355

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Abstract

Complex boundary conditions are the major influencing factors of coal caving law in the pseudo-inclined working face. The main purpose of this study is to analyze coal caving law of flexible shield support and then to establish the internal relations among coal caving parameters under complex boundary conditions. Firstly, the law of coal caving in different falling modes is simulated physically. Secondly, the coal caving shape, displacement field, and contact force field is simulated. Then, coal caving law and process parameters is analyzed theoretically. Finally, the test was performed in Bai-Ji Mine. The research shows that ellipsoidal ore drawing theory has universal applicability in coal drawing law analysis and parameter optimization. After the Isolated Extraction Zone and Isolated Movement Zone reach the roof, the expansion speed is marked by a short delay, and then, while expanding to the floor, two butted incomplete ellipsoids are formed. There is a time-space difference in coal caving after the support, and some coal will be mined in the next round of coal caving. There are obvious differences in the coal loosening range, displacement field, and contact force field on both sides of the long axis. When the support falls along with the bottom plate, it is more conducive to the release of coal. The test shows that the research is of great significance for optimizing the caving parameters of flexible shield support in the pseudo-inclined working face of the steep seam.

Highlights

By understanding the basic rules of draw, namely, the gravity flow of fragmented ore and rock during the draw process, the caving method can be applied efficiently, and the ore loss and dilution can be decreased to the greatest degree [1,2,3]
Based on the self-designed experimental platform, this paper systematically studied the law of the coal body behind the flexible shield support through theoretical analysis, physical simulation, numerical simulation and industrial test, and discussed the influence of falling mode and boundary conditions on the drawing law of the coal body
The analysis shows that before the formation of slip surface, the upper coal body will continuously slide to the ellipsoid, which leads to a certain lag in the expansion of the lower loose ellipsoid compared with the expansion of the upper range loose of coal body

Summary

Introduction

By understanding the basic rules of draw, namely, the gravity flow of fragmented ore and rock during the draw process, the caving method can be applied efficiently, and the ore loss and dilution can be decreased to the greatest degree [1,2,3]. Law of coal caving in pseudo-inclined working face www.nsfc.gov.cn/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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