Improved compound support system for coal mine tunnels in densely faulted zones: A case study of China's Huainan coal field

When tunnelling in densely faulted zones of coal mines, serious deformation often occurs due to adverse geological conditions such as extremely broken and weak rock mass, high tectonic stress, fissure water. To investigate a more efficient support strategy for tunnels passing through densely faulted zones, a tunnel in China's Huainan mining area is taken as an experimental site to study an improved support method. Some key factors associated with the stability of tunnels in the densely faulted zone are analysed. Based on the analysis of failure characteristics of a previously excavated tunnel, a detailed procedure for the improved support method is proposed in which a long pipe pre-grouting method together with a new kind of grouting cable are applied. Finally, the improved support strategy is implemented in the experimental tunnel. The monitoring results suggest that serious deformation is avoided, and the improved compound support method is feasible for tunnels in densely faulted zones.