穿越泥石流冲沟隧道施工关键技术研究

Key Technology Study on Construction of Tunnel across the Mudsfide Gully

以绵九高速公路甘沟隧道工程为依托,基于现场资料建立数值模型进行模拟,并依据数值模拟结果及现场监测变形数据对洞口段施工关键技术进行优化;将优化后的数值模拟结果与原施工技术下的结果进行对比,探究穿越泥石流冲沟隧道洞口段较好的施工技术。结果显示:原有施工技术下穿越泥石流冲沟隧道开挖时,拱顶累计沉降、周边累计收敛变形以及地表累计沉降均较大;而施工技术优化后的数值模拟结果显示围岩变形及受力均有较大幅度下降。由此可见:采用单层小导管并结合帷幕注浆的联合超前支护方式以及三台阶开挖工法后,围岩变形及受力较好。

Based on Gangou tunnel project of Mianjiu Expressway,we conducted simulation test with a numerical model containing field data,followed by optimization of key construction technology at the tunnel opening segment in combination with the obtained numerical simulation results and deformation data.The optimized numerical simulation results were compared with those derived from the original technology,and a technology suitable for construction of tunnel opening segment across the mudslide gully was figured out.The results showed that the tunnel excavation across the mudslide gully with the original technology had led to the obvious indication of cumulative settlement at the vault crown,cumulative peripheral convergence deformation and cumulative ground settlement.On the other hand,the numerical simulation results with the optimized technology showed the significant reduction in the surrounding rock deformation and stress.Therefore,it was concluded that improvement of the surrounding rock deformation and stress was achieved as a result of application of single layer small-lead-tube in combination with that of curtain grouting-based combined forepoling and three-step excavation method.