Study on surrounding rock failure characteristics and control technology of gob-side entry retaining in"three hard" thin coal seam

Abstract

This study aims to address existing problems of complex stress conditions and difficulties in retaining roadway so as to achieve long-term stability of roadway surrounding rock in gob-side entry in thin coal seam. Specifically, we investigated the 4301 working face of Liangshuijing Coal Mine in Huisen Coal Industry of Shaanxi Province through theoretical analysis, numerical simulation and engineering practice, with an aim to study the failure characteristics and control countermeasures of surrounding rock of gob-side entry retaining in shallow buried "triple hard" thin coal seam, and analyse the influence of structural parameters of roadside support on roadway stability. The results show that 1)maintaining the roadway through roadside filling body requires sufficient support strength and appropriate shrinkage to the roof and ensuring the overall stability of the roadway; 2)the mechanical behaviour of high water filling material under uniaxial compression can be divided into four stages: "uniform compaction, elastic deformation, dynamic instability and deterioration failure". The numerical simulation results show that in increasing the width of the filling body, the maximum stress first increases, then decreases and then increases, and a stable bearing stress core appears at 1.6 m. Theoretical calculation shows that the optimal height of roof cutting is 10.7 m, and it offers the roof cutting scheme and parameters of shaped blasting. Engineering practice shows that there is no large deformation and no obvious stress concentration in the 60 m range behind the working face. The surrounding rock exhibits good overall control effect and stable structure, and the effect of retaining roadway meets the design requirements.

Keywords

• thin coal seam
• gob-side entry retaining
• high water material
• energy-gathering blasting