Optimization Of Curtain Grouting Range for Water-Rich Fault Tunnel

When the tunnel is excavated through the water-rich fault, it is easy to cause the problems of water surge and the instability of the face of the tunnel. The advanced curtain grouting can effectively improve the rock mass quality and water permeability of the fault broken zone, and ensure the safety of the construction. In view of this, MADIS-GTS finite element software is used to establish dynamic excavation models under the conditions of no curtain grouting and curtain grouting. The deformation and water seepage characteristics of the palm surface were compared and analysed to determine the fortification length, optimal grouting thickness and optimal grouting length of the curtain grouting before the fault. The results show that :(1) The timing of the connection between rock mass and fault plastic zone in front of the palm head is roughly the same as the timing of the deformation of the palm head face and the surge of seepage velocity. When the palm head face is about 0.5 times the tunnel diameter from the fault plane, the fortifications length of the curtain grouting should also be 0.5 times the tunnel diameter. (2) The increase of grouting length and thickness will reduce the risk of instability of the palm face. When the grouting length exceeds 12m and the grouting thickness exceeds 3m, the influence on the palm face is not obvious. The research results can provide reference for the curtain grouting design of tunnel through fault in the future.