A case study on new high-strength temporary support technology of extremely soft coal seam roadway

One of the main challenges in excavating roadways is implementing temporary supports that are powered by hydraulics and have high strength. The current temporary support system lacks active support and often causes separation between the top plate and the layer below. It is crucial to control the initial separation of the roadway roof for the stability of the surrounding rock, especially on roadways with loose and soft rock. This research focuses on the A4027 return airway in Sail Six Mine. The issues with the temporary support system in this airway have been identified. The concept and principle of using hydraulically driven, high-strength temporary support technology are proposed. A mechanical analysis model is created to study the stacked roof in the temporary support region, and the critical conditions for delamination of the top plate are determined. The relationship between the delamination difficulty parameter Q, the distance between temporary supports L, and the strength of the temporary supports q is quantified. Numerical simulation using Flac3d is used to model the relationship between the strength of the temporary supports and the deformation and stress of the rock on the roof. The overall strength of the temporary supports for the A4027 return airway is determined to be 10 kN/m(2), with a distance of 2 m between the temporary supports. Hydraulically driven, high-strength temporary support devices are developed and tested for their strength. Field trials are conducted as well. The results show that the initial separation of the top plate is improved and that the support effect in the temporary support region is significant. The maximum separation of the top plate during excavation is only 34 mm, and the sinking of the top plate does not exceed 68 mm. This effectively limits the deformation of the surrounding rocks in the very soft coal seam, providing valuable insights for other roadways with similar conditions.