Stability Analysis of Long-Span Temporary Support Roofs in Coal Mine Roadways Using Multistation Parallel Excavation Technology

The parallelisation of excavation and support operations remains a significant challenge for the rapid advancement of coal mine roadways. This study proposes an excavation technology incorporating multistation parallel operations. The roof stability of the large-span temporary support system, a core of the multistation parallel excavation system, was systematically investigated through theoretical analysis, numerical simulations and field experiments. The established mechanical model shows that the roof deformation of the unsupported area is serious and highly sensitive to the span. Subsequent numerical simulation using FLAC^3D shows that the large-span temporary support system significantly improves the roof stability. Key results show that the support improves the vertical stress σ_zz distribution, reducing the peak stress at the header′s leading edge by 1.32 MPa. Roof displacement distributions became more uniform, with a maximum displacement reduction of 79 mm. Furthermore, the system drastically reduced plastic damage, achieving a 97.93% decrease in surface tensile damage volume and a 21.50% reduction in total plastic damage. The preliminary testing of the ZLC-442 temporary support device verified the feasibility of its operating mode and its adaptability to underground working conditions. This research provides critical theoretical and technical insights for enabling safe and efficient parallel excavation-support operations in underground coal mines.