Study on stability mechanism and control techniques of surrounding rock in gob-side entry retaining with flexible formwork concrete wall

Abstract

Gob-side entry retaining (GER) is a technique in non-pillar mining, which maintains the original mining roadway along the edge of gob and retains it as a mining roadway for the subsequent working face. This technique offers significant advantages such as a high coal mining rate and cost-effective roadway retention. This paper focus on the GER implementation in 52605 panel of Daliuta Coal Mine and introduce an innovative technique involving the utilization of flexible formwork concrete wall (FFCW). To verify the feasibility of this technique, a numerical model was established. Furthermore, the stability mechanism of surrounding rock during the mining process of 52605 panel was thoroughly examined. Simulation results indicate that during the mining, the roadside backfill body (RBB) gradually bears load, causing peak stress transfer from gob side towards solid coal side. Moreover, plastic zone of roof and solid coal exhibited a noticeable increase, leading to a combined tensile-shear failure. Based on the stress and plastic zone evolution characteristics of surrounding rock during the mining process of the working face, control techniques were proposed and industrial experiment was successfully carried out. Ultimately, on-site monitoring results show that the deformation control effect of surrounding rock was good, and there was no obvious pressure manifestation in the working face.

Keywords

gob-side entry retaining / flexible formwork concrete wall / gangue retaining bracket / control technique / numerical modeling

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