西南山区高速铁路隧道衬砌脱空对结构安全的影响分析

The Influence Analysis of Structure Safety by Voids in the Composite Linings of High Speed Railway Tunnels in Southwest China

摘要: 在西南山区高速铁路隧道的建设过程中，由于隧道开挖断面较大，当围岩条件较好时，受地质及施工等因素的影响，隧道二次衬砌与围岩脱空的现象较为普遍。衬砌脱空导致隧道衬砌开裂、掉块、漏水，降低结构耐久性，是一种严重危害高速铁路行车安全的病害。为了研究二衬脱空位置及脱空面积对衬砌结构内力以及结构安全造成的影响，针对西南山区典型的灰岩隧道断面，建立了脱空计算的地层–荷载模型，计算10种不同脱空位置及脱空面积下二衬内力，进而得到截面安全系数K。通过某隧道的无损检测结果，讨论了引起二衬脱空的4种主要原因，分别是：开挖、混凝土浇筑、模板台车强度以及防水板安装。结合工程实例，最后分析了脱空对二衬结构安全的影响，为高速铁路隧道脱空防治提供一定的理论基础。

Abstract: In high speed railway tunnel constructing process of southwest China, due to large size of excavation with good conditions of surrounding rock, the voids between tunnel secondary lining and surrounding rock are relatively common affected by factors such as geology and construction. The voids cause lining crack, impellers and leakage and reduce the durability of structures. The voids are a kind of factor which causes serious damage to the operation safety of high speed railway train. In order to study the influence effects of voids position and area on internal forces and structure security, using typical Karst tunnel section, the paper establishes formation-load model, calculates lining internal force of 10 different voids position and area and thus obtains section safety coefficient K. Through nondestructive testing results of a tunnel, the paper discusses the four main causes of secondary linings voids, that is: excavation, concrete pouring, templates pallet strength and waterproof board installation. The paper analyzes the security influence of voids for secondary linings at last, and provides theoretical basis of voids prevention in high speed railway construction.