浅埋隧道塌方地质灾害成因及风险控制

塌方是浅埋隧道施工过程中的主要地质灾害之一，利用风险动态评估模型及风险规避方法进行实时控制是确保隧道施工安全的有效途径。首先，采用洞内外相结合的地质调查方法，分析隧址区地质特征及塌方灾害风险诱因，并建立浅埋隧道塌方风险模糊层次评价模型，进行基于孕险环境的静态风险评估；其次，根据隧道施工过程中揭露的动态信息，对孕险环境进行动态修正，并汲取大气降水、开挖支护措施及监控量测等施工信息，进行隧道施工过程中的动态风险评估；最后，基于动态评估结果提出了风险规避方法，通过对施工方案的审核和优化，达到逐渐降低隧道施工风险、规避地质灾害的目的。该方法成功应用于宜巴高速公路段家屋隧道施工过程中，有效地规避了塌方地质灾害的发生，可为同类工程所借鉴。

Causes of geological hazards and risk control of collapse in shallow tunnels

Collapse is one of the typical common geological hazards during the construction of shallow tunnels. Real-time control conducted using dynamic evaluation model and risk aversion is an effective way to ensure the safety of tunnel construction and can be fallen into the following procedures: ①Based on the geological conditions in and out of the tunnel, the risk factors of collapse are analyzed and a fuzzy analytic hierarchy process (FAHP) model of risk assessment for tunnel collapse is proposed. Static evaluation of collapse is then conducted using the risk environment and the proposed model. ②The risk environment is updated based on the actual geological conditions. Furthermore, dynamic evaluation is carried out according to the risk environment, meteoric water, excavation method, support measures and monitoring measurement. ③A risk aversion method is proposed using the results of dynamic evaluation. The purpose of risk reduction can be realized through the optimization of construction scheme. The presented approach has been successfully applied to the construction of Duanjiawu tunnel to avoid collapse, which can provide references to the risk assessment of other similar engineering cases.