Optimization of Pipe Shed Support Parameters for Shallow Buried Bias Pressure and Small Clear Distance Tunnels
In order to study the influence of the combined advanced support parameters of shallow bur-ied bias and small clear distance tunnel pipe shed plus advanced small conduit on the tunnel support effect,relying on the Yiliang tunnel entrance section project,the three-dimensional model working con-ditions under different parameters such as thickness,length,diameter,hoop spacing and extrapolation angle of the grouting reinforcement area of the pipe shed were established through FLAC3D,and the con-trol effect of each pipe shed parameter on the displacement of the surrounding rock was analyzed.The results show that the displacement of the surrounding rock can be reduced by increasing the thickness,diameter and length of the grouting reinforcement area.A grouting reinforcement zone with a thickness of 3 meters,a pipe shed diameter of 100 mm,and a length of 40 meters are preferred.With the in-crease of the interpolation angle and hoop spacing of the pipe shed,the displacement of the surrounding rock gradually increases.The interpolation angle of the pipe of 2° and the hoop spacing of 0.3 m are preferred.Based on the selection of reasonable support parameters for the pipe shed,the simulated val-ues are compared with the on-site monitoring measurements to verify the rationality and reliability of the selected support parameters.
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