隧道穿越泥石流堆积体的数值模拟及优化处治

根据泥石流堆积体的地质特征, 结合都汶高速公路福堂隧道工程背景, 建立三维数值模型, 分别进行隧道穿越泥石流堆积体时无支护状态、设计支护状态和优化支护状态下以及泥石流堆积与侵蚀条件下的模拟分析。结果表明:在泥石流堆积体内开挖隧道时, 拱顶沉降是隧道变形的主体部分, 并直接导致了地表的沉陷及隧道边墙的收敛变形; 在采用超前注浆并加长锚杆长度的措施进行针对性的优化处治后, 隧道衬砌的变形及地表沉陷明显降低, 表明处治优化是有效的; 隧道拱顶上方泥石流覆盖层的厚度小于14m时, 隧道处于明显不安全状态, 泥石流覆盖层厚度大于42m时, 围岩形成自稳体系。

NUMERICAL SIMULATION AND OPTIMIZATION OF TREATMENT MEASURESFOR A TUNNEL EXCAVATED THROUGH DEBRIS FLOW FAN

Based on geologic features of debris flow fan, combined with the engineering background of Futang tunnel in Dujiangyan to Wenchuan expressway, a 3D numerical model had been established to study tunnel excavation and support in debris flow fan. The paper presents different modelling conditions, including the non-support status, designed support status, optimizing support status as well as the deposition and erosion of debris flow fan. The study results show that, tunnel excavated in debris flow fan, the vault settlements are main controlling factor and lead to subsidence and side wall convergence; after pointed optimizing treatment to vault settlement using the advanced grouting and the systematical anchor lengthening, deformation of tunnel lining and subsidence are reduce markedly, it shows that the optimizations are effectual and reasonable. In addition, if the deposition thickness of debris flow above tunnel vault is less than 14 m, the tunnel is in obvious unsafe condition; if the debris flow thickness is more than 42 m, the stability of surrounding rock will become better and be easy to form a stabilizing system.