Abstract

Gob-side entry retaining, also termed as non-pillar mining, plays an important role in saving coal resources, high production and efficiency, extending the service life of mine and improving the investment benefit. Herein, a gob-side entry retaining method involving the use of bag filling material for wall construction is proposed based on the thin seam mining characteristics. First, a gob-side entry retaining mechanical model is established, and the side support resistance of the 8101 working face is calculated. The mechanical properties of the bag material are investigated through experiments, and the construction technology of the gob-side entry retaining approach involving the use of bag filling material for wall construction is introduced. The deformation on the two sides, the roof and floor of the roadway, are simulated via numerical methods and monitored during field tests. The results show a small control range for the deformations and a good roadway retention effect, thereby proving the feasibility of the bag filling material for wall construction. This study provides a reference for the development of gob-side entry retaining mining for thin coal seams.

Highlights

  • Gob-side entry retaining involves the preservation of the entire tailgate of the previous working face for use in the one [1,2,3]

  • The gob-side entry retaining technology is characterized by direct significant effects including coal resources saving, investment benefit improvement, and mining life prolongation

  • Field monitoring was conducted to better understand the effect of gob-side entry retaining involving the use of bag filling material for building an 8101 working face, especially the roof

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Summary

Introduction

Gob-side entry retaining involves the preservation of the entire tailgate of the previous working face for use in the one [1,2,3]. The key feature of this technology is the construction of a wall ( termed roadway side) to replace the traditional method of retaining coal pillars at the end support and along the working face [4,5,6]. Studies on gob-side entry retaining are common and have obtained important results, the most commonly constructed roadway sides include the grouting concrete wall method and the paste filling method. The former method, involves the use of a rigid supporting roof, and thereby exerts a shear failure effect on the roof. The proposed technology is expected to contribute to the promotion of gob-side entry retaining development

Gob-Side Entry Support Resistance Calculation
Material Ratio and Bag Preparation
Mechanical Properties of the Materials
Stress Conditions at the Roof and Floor of the Support Body
Field Monitoring
Single Hydraulic Prop Monitoring Analysis
Roof Separation Observation Results Analysis
Bolt Stress Monitoring Analysis
Findings
Analysis of Deformation on the Roadway Sides and Near the Roof and Floor

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