Abstract

The surrounding rock failure range of floor drainage roadway under the mining influence and its effect on the aquiclude are the key to determine the aquiclude thickness of the floor. This paper studied the distribution characteristics of the surrounding rock plastic zone by the numerical simulation when the floor drainage roadway was located at different positions under the working face and determined the rational position. Results show that (1) when the floor drainage roadway is staggered inward, the floor surrounding rock is prone to appear the butterfly plastic zone under single work face mining. And the butterfly plastic zone increases sharply after being affected by secondary mining of adjacent working face. (2) When the floor drainage roadway is staggered outward, the floor surrounding rock plastic zone extends gently affected by a single working face. And the depth of the plastic zone has no obvious change after being affected by secondary mining of adjacent working face. (3) According to the risk of water inrush, the three layout schemes can be ranked as follows: stagger inward 25 m > stagger inward 80 m > stagger outward 15 m . (4) Considering the floor stress environment, gas extraction efficiency, and water prevention and control, the reasonable location of floor drainage roadway below the No. 11060 working face of Zhaogu No. 2 Coal Mine was finally determined. It was arranged in the sandy mudstone layer on the upper part of L9 limestone under the middle part of coal pillar and was drived along the seam floor.

Highlights

  • To prevent the occurrence of coal and gas accidents, floor rock roadway is sometimes designed to extract gas from upper coal through layers [1,2,3,4]

  • (2) When the floor drainage roadway is staggered outward, the floor surrounding rock plastic zone extends gently affected by a single working face

  • The depth of the plastic zone has no obvious change after being affected by secondary mining of adjacent working face

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Summary

Introduction

To prevent the occurrence of coal and gas accidents, floor rock roadway is sometimes designed to extract gas from upper coal through layers [1,2,3,4]. The damage extent of the rocks around the drainage roadway directly determines the risk of floor water inrush. The research on stress environment and failure characteristics of surrounding rock in floor roadway mainly focuses on obtaining the stress distribution in floor rock mass by using elastic mechanics theory and calculating the maximum failure depth of floor combining with relevant failure criteria [22,23,24,25]. In this study, based on the contradiction between gas drainage demand and floor water inrush risk in Zhaogu No 2 Coal Mine, the plastic zone distribution characteristics of surrounding rock in different positions under the working face were studied by numerical simulation, and the reasonable position of floor drainage roadway was determined

Case Engineering Background
Layout Scheme of Floor Drainage Roadway
Surrounding Rock Failure Law of Floor Drainage Roadway under Mining Influence
2-1 Coal seam
2-1 Coal seam Mudstone
Conclusions
Full Text
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