隧道初期支护全过程安全性评价方法研究

Study on safety evaluation method of the whole process of tunnel initial support

考虑隧道施工过程中初期支护结构的安全性对于施工期隧道的稳定性具有重要意义。文章基于理论推导分析、数值计算等方法,建立了考虑开挖面空间效应的围岩压力计算方法,并结合喷射混凝土硬化特性,实现了对施工过程中初期支护安全性的判定。结果表明:隧道开挖早期的初期支护安全系数较其稳定时的初期支护安全系数小,故隧道初期支护设计时应考虑施工过程中初期支护的安全性。喷射混凝土的硬化特性对于初期支护早期的安全性具有较大影响作用,提高其早期强度特性,可有效保证隧道开挖早期的支护结构的安全性。

Considering the safety of the initial support structure during the tunnel construction process is of great significance for the stability of the tunnel during the construction period.Based on theoretical derivation,numerical calculation and other methods,this paper establishes a calculation method for surrounding rock pressure considering the spatial effect of the excavation face,and combines the hardening characteristics of shotcrete to realize the determination of the safety of the initial support during the construction process.And through the analysis of the example,it can be seen that the safety factor of the initial support in the early stage of tunnel excavation is smaller than that of the initial support when it is stable,so the safety of the initial support in the construction process should be considered in the design of the initial support of the tunnel.The hardening characteristics of shotcrete have a great influence on the safety of initial support in the early stage,and improving the early strength characteristics of shotcrete is of great significance to ensure the safety of the early support structure of tunnel excavation.