Mechanism Analysis of Roof Deformation in Pre-Driven Longwall Recovery Rooms Considering Main Roof Failure Form

Abstract

Pre-driven recovery rooms are used extensively for the removal of mining equipment and hydraulic supports in longwall coal mining. Roof stability is a crucial factor influencing the speed and safety of the removal of operators in pre-driven recovery rooms. The characterization of roof deformation mechanisms in recovery rooms under front abutment pressures is significant for surrounding rock control and stability evaluation. In this study, three different roof subsidence evaluation models, considering different main roof failure forms, were established. It was noticed that the main roof break position had a significant effect on recovery room roof sag. The breaking of the main roof above the main recovery room and protective coal pillar was found to be the main driving force for large roof deformations. Furthermore, field monitoring data of roof sag and coal pillar stress in the 15205 and 15206 panels of Hongliulin Coal Mine were analyzed. According to evaluation models and field monitoring data, we propose determination methods for the evaluation of recovery room roof sag and main roof break position. During the study it was found that the inversion results of the main roof break position of the recovery room in 15205 and 15206 panels were 4.2 m and 9.1 m, respectively, which are basically consistent with the results calculated by periodic weighting. The research findings provide a reference for the quantitative evaluation of recovery room roof stability and the design of support parameters and yield mining.

Analysis of Mechanical-Hydraulic Cooperative Response of Hydraulic Support Under Roof Rotary Impact

“…Under working conditions, the hydraulic support is in the' basic roof -upper immediate roof -hydraulic support -floor' coupling system [28], [29]. Influenced by the rock stiffness and support strength, the rotary speed of the roof after fracture is different, and the impact effect on the support is also different.…”

Study on Stability and Control of Surrounding Rock in the Stopping Space with Fully Mechanized Top Coal Caving under Goaf

“…The mining of thick coal seams is the main part of coal mining in China, and fully mechanized top coal caving is the first choice for thick seam mining [3][4][5]. After the mining of the working face is completed, the retracement channel is reserved in order to facilitate the rapid withdrawal of hydraulic supports, shearers, and other equipment [6]. At present, equipment withdrawal is performed in mainly two ways: predriven retraction channel and non-pre-driven retraction channel [7].…”