Evolution process and lateral pressure distribution of gangue side in roof cutting entry retaining

The success of gangue support in roof cutting and retaining roadway depends on the evolution process of gangue side and its lateral pressure distribution. Based on the engineering background of Xinghua Coal Mine, this paper analyzes the mechanical characteristics of gangue compaction, the roof caving process, and the gangue side evolution process through indoor experiments and similar simulations. The mechanical model is established through theoretical analysis, and the impact of different factors on the lateral pressure of the gangue side is analyzed. The numerical simulation gives the distribution law of the overburden pressure and the lateral pressure of the gangue side at the boundary of the goaf and gives the gangue side support scheme from the perspective of gangue side lateral pressure influencing factors. The research results show that : ①The lateral pressure of the gangue side is related to the evolution process of the gangue in the goaf. In the self-organizing adjustment stage of the gangue, the lateral pressure of the gangue side is mainly generated by the self-weight of the gangue, and the lateral pressure depends on the accumulated height. In the passive compaction stage of gangue, the gangue body is repeatedly compacted under periodic roof pressure, and the lateral pressure of the gangue side gradually increases. In the stable stage of gangue, the gangue body is compacted at this stage, which plays an obvious supporting role in the overburdened rock. The stable value of the overburden pressure is 3.81 MPa, and the stable value of the gangue side lateral pressure is 2.12 MPa. ②From the position of the roof of the roadway to the position of the floor, the lateral pressure of the gangue side gradually increases. ③From the perspective of the external environment, the lateral pressure of the gangue side has a significant positive correlation with the roof overburden pressure and a significant negative correlation with the roof cutting angle. From the perspective of the gangue’s mechanical properties, the gangue side’s lateral pressure and the gangue’s internal friction angle show a significant positive correlation. Consequently, the “bag + net + u-shaped steel + inclined support monomer” gangue retaining support scheme is proposed, and the field application effect is good. This study may provide a reference for similar engineering conditions of gangue support.