Abstract

Setting up a waterproof coal pillar is an important measure to prevent water inrush from the Weibei mining through fault floor. Based on the plastic slip line field theory, a mechanical model of floor water inrush induced by confined water in the through fault zone was established. The mechanical expressions of confined water pressure and the width of the waterproof coal pillar under the state of limit equilibrium were derived. Combining the laws of floor deformation, failure and fault activation under two kinds of coal pillar width, the safety width of the waterproof coal pillar was determined. Furthermore, the safety threshold is better than the empirical value mentioned in the “coal mine safety regulations.” Following this, grouting transformation was carried out on the K2 sand layer of the cut roadway floor. This provided a theoretical basis and engineering practice for water disaster prevention and the control of the structural floor under similar conditions in the Weibei mining area for future benefit.

Highlights

  • The North China-type coalfield is rich in coal resources and accounts for about 90% of the total coal [1, 2]

  • In some old mining areas, coal reserves threatened by karst water disasters account for 49%-87.6% of total mine reserves [9]

  • This paper analyzed the activation law of floor fault in the 23503 working face of the Dongjiahe coal mine. It verified the theory by numerical simulation and engineering practice

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Summary

Introduction

The North China-type coalfield is rich in coal resources and accounts for about 90% of the total coal [1, 2]. Wang et al [21] established an evaluation model for predicting water inrush in the Lu-an mining area based on fractal theory and improved the analytic hierarchy progress. This model provided a basis for water inrush research from the floor strata through faults. The study on the mechanism of water inrush and seepage from the through fault floor in the Weibei mining area has not yet taken a corresponding karst confined water prevention. Setting waterproof coal pillar measures is often adopted to prevent water inrush from the Weibei coal mine floor. The grouting of floor K2 sandstone can be used as a reference for the treatment of other similar geological structures

Theoretical Analysis
Engineering Practice and Application
Calculation of Setting Width of the Fault Coal Pillar
Numerical Simulation Study on 28 m Width of the Waterproof Coal Pillar
Engineering Practice
Findings
Conclusions
Full Text
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