Research on active advanced support technology for gob-side entry retaining with roof cutting and pressure relief in ultra-soft thick coal seams

Zhang Sheng; Xu Ruize; Liu Jiawei; Zhu Ranghe; Ma Qiang; Wang Gaoshang; Zhang Fan; Zhao Longgang

doi:10.16186/j.cnki.1673-9787.2024030061

Abstract：Objectives Roof cutting and pressure relief gob-side entry retaining technology is widely used in coal mining in China.However,in the case of extremely soft and thick coal seam roadways,challenges such as soft coal on the sidewalls and large roadway heights arise.Traditional passive advanced support techniques often lead to roof damage and limited working space.Therefore,it is essential to develop ad-vanced support technologies for retained roadways.Methods Taking the 32021 roadway in Liangbei Coal Mine as the engineering background,a mechanical model was established to analyze the stability of the sur-rounding rock in the advance section of the roadway before and after pre-splitting roof cutting.The stress characteristics and deformation patterns of the roof in the advance section were studied,revealing the defor-mation mechanism of the surrounding rock influenced by pre-splitting roof cutting.Numerical simulations using FALC3D software were conducted to analyze the stress distribution of the roadway under directional blasting roof cutting conditions.An active anchor cable beam collaborative anchoring scheme was proposed,support parameters for active advanced support were designed,and the field applications were performed.Results The results indicated that the pre-splitting roof cutting effectively interrupted stress transfer be-tween roof layers,placing the surrounding rock of the advance section in a stress reduction zone and reduc-ing the hanging roof area at the junction of the working face and the retained roadway.Numerical simula-tions validated that the proposed anchor net cable beam could effectively control the deformation of the sur-rounding rock in the advance section after active support,contributing to the long-term stability of the road-way.Field applications demonstrated that the maximum displacement of the roof and floor did not exceed 80 mm,roof deformation was reduced by 35%,and the integrity of the roadway roof was significantly pre-served.Conclusions The proposed active advanced support technology addresses challenges such as narrow working spaces,high labor intensity,and repetitive roof support damage.It offers valuable insights for implementing advanced support methods for gob-side entry retaining under similar mining conditions.