隧道洞口浅埋段管棚超前支护开挖进尺优化

Optimization of Excavation Footage of Shallowly-buried Section of Tunnel Portal Supported by Advance Pipe Roof

山岭隧道矿山法施工循环作业的开挖进尺对该隧道工程局部乃至整体的施工安全性、经济性有着重大影响。针对使用管棚超前支护的隧道洞口浅埋段,采用Winkler弹性地基梁计算模型,以管棚钢管挠度为控制条件进行开挖进尺优化分析。以厦深高速铁路某双线隧道工程为依托,首先进行理论计算,同时考虑工程实际确定最优开挖进尺并指导施工,随后将现场实测数据与理论解析值对比,两者有较好的一致性。结果表明,Winkler弹性地基梁计算模型可以较真实地反映管棚在洞口浅埋段软弱破碎围岩中的力学行为。

For mountain tunnels constructed by mining method, the excavation footage of one operation cycle has significant influence on local and even overall construction safety and economic efficiency. Aiming at the shallow-buried section of tunnel portal supported by advance pipe roof, using Winkler elastic foundation beam model, and taking the deflection of steel pipe of the pipe roof as the controlling condition, the excavation footage was optimized and analyzed. Meanwhile, citing a double track tunnel on Xiamen-Shenzhen High-speed Railway as an example, the theoretical optimal excavation footage was calculated, and at the same time the actual situation of the tunnel project was taken into account to determine the optimal excavation footage so as to guide the construction. Subsequently, by comparing the field test value with the theoretical analysis value, it can be seen that there is a good conformity between the two values, which proves that the Winkler elastic foundation beam model can truly reflect the mechanical behavior of the pipe roof in the weak and fractured surrounding rocks at the shallow-buried section of tunnel portal.