Stability Control Technology for Surrounding Rocks in Gob-Side Entry Driving with Small Coal Pillars under Dynamic Pressure

Abstract

To address the support difficulties caused by the dynamic pressure from the adjacent working face in gob-side entry driving, this study, taking the 8103 working face of the Jinhuagong Coal Mine in Shanxi Province as an example, adopted methods such as theoretical analysis, physical experiments, numerical simulations, and field practices to explore roof-cutting and pressure-relieving techniques to control the surrounding rocks in gob-side entry driving with small coal pillars under dynamic pressure. Fractures of the lateral roof, stresses on the surrounding rock, and deformations with different cutting-roof parameters were analyzed to determine the reasonable parameters for applications. The following results have been obtained. The longer the lateral cantilever length of the roof, the greater the load borne by the surrounding rock. Therefore, the key to reducing the confining pressure in a roadway is reducing the lateral cantilever length of the roof. After roof cutting, the roof of the gob area collapsed more completely. The stress on both sides of the coal pillar and that on the ribs of the solid coal dropped by 7.72 MPa and 4.16 MPa, respectively. The key roof-cutting parameters were analyzed by the UDEC numerical software, and the reasonable roof-cutting angle and height were determined to be 12° and 14 m. A support scheme combining “steel strip + bolt + anchor cable + roof cutting” was proposed. With the scheme applied, the displacement of both sides of the coal pillar was 61 mm shorter than that in the non-test section, and the duration in which the roadway was affected by mining was 11 days shorter. Therefore, the rationality of the selected roof-cutting and support parameters in this study is verified. The proposed scheme can effectively control the stability of surrounding rocks in gob-side entry driving with small coal pillars under dynamic pressure.