浅埋偏压小净距隧道管棚支护参数优化研究

为研究浅埋偏压小净距隧道管棚+超前小导管联合超前支护参数对隧道支护效果的影响，依托彝良隧道洞口段工程，通过FLAC^3D建立不同管棚注浆加固区厚度、长度、直径、环向间距和外插角度等参数下的三维模型工况，分析各管棚参数对围岩位移的控制效果。结果表明：增大管棚注浆加固区厚度、直径和长度可降低围岩位移，注浆加固区厚度为3 m、管棚直径为100 mm和长度为40 m较佳；随管棚外插角度和环向间距的增加，围岩位移逐渐增大，管棚外插角度为2°和环向间距为0.3 m较为合适。在管棚合理支护参数选择的基础上，将模拟值与现场监控量测值对比，验证所选支护参数的合理性和可靠性。

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 buried 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 conditions 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 FLAC^3D, and the control 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 increase 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 values are compared with the on-site monitoring measurements to verify the rationality and reliability of the selected support parameters.