Study on Stability of Advance Self-propelled Anchor Rod for Fault Breccia Tunnel

For heavily weathered fault breccia tunnel, advance support is prone to problems such as jamming and difficulty in forming holes, and tunnel excavation can easily cause tunnel face collapse, resulting in safety hazards. In order to solve the problem of advance construction in fault breccia tunnel, a successful application of self-propelled hollow grouting anchor rod advanced construction technology in Beijing Yudushan Tunnel was introduced, and the advantages of self-propelled hollow grouting anchor rod as advanced support in fault breccia tunnel instead of ordinary advanced small conduits was analyzed. It is concluded that a reasonable increase in the initial support strength of the fault breccia tunnel can inhibit the expansion of the plastic zone of the tunnel surrounding rock to enhance the stability of the surrounding rock. Combined with the field situation, the mechanical model of fault breccia tunnel was established to analyze the plastic zone of surrounding rock. The reasonable support parameters and grouting pressure for the self-propelled anchor rod were determined by test comparison. The reasonableness of these parameters was also verified based on the effect of the advanced support after excavation of the tunnel face, which provides a reference for similar strata.