ABSTRACT Gob‐side entry retention represents a major technological innovation in the history of coal mining, offering numerous advantages such as enhancing coal resource recovery rate, facilitating ventilation, and reducing an additional roadway. Taking the gob‐side entry retention of headgate in 11305 longwall face as an example, the uniaxial compressive strength of coal seam are measured to be 19.94 MPa through laboratory tests. It is determined that fracture location of main roof above the gob‐side entry retention is situated above solid coal by borehole observations. A three‐dimensional numerical model for surrounding rock of gob‐side entry retention is established. The failure ranges of roof and solid coal in gob‐side entry retention are 5.82 m and 4.65 m based on the stress field and plastic zone distribution characteristics of surrounding rock, respectively. A support strategy is proposed, wherein anchoring end of anchor cable must penetrate the boundary line of stress peak (plastic zone). Specifically, a coupling technology combining bolt, anchor cable, and through‐bolt is adopted. Through on‐site engineering practice and mine pressure observation, it is found that the maximum convergences of roof and two ribs are 274 mm and 258 mm, respectively. The anchor cable forces exerted on roof and two ribs are 246 kN and 198 kN, respectively, while single pillar forces in the roadway remained stable within the range of 175 ~ 200 kN. The feasibility of the support technology is verified, ensuring the safe and orderly extraction of the longwall face. It provides significant reference for roadways support design under similar conditions.
Liang et al. (Thu,) studied this question.
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