回头沟隧道洞口浅埋偏压段开挖方法比选研究

以回头沟隧道工程洞口段为例，针对偏压隧道常用施工方法，对台阶法、环形开挖留核心土法、CRD法、单侧壁导坑法等开挖方法进行模拟分析，从控制围岩变形以及围岩塑性区范围，减小围岩应力集中方面分析，单侧壁导坑法优于其他三种方法，但结合隧道工程条件，从施工工序，施工工期方面分析，在实际施工时可以采用台阶法进行开挖。

Study on Excavation Method of Shallow Buried Bias Section in Huitougou Tunnel Portal

This paper takes the Huitougou tunnel as an example, aiming at the common construction method of bias tunnel, the excavation methods such as step method, ring excavation with reserving core soil method, CRD method and unilateral pilot tunnel method are simulated and analyzed. In the controlling range of surrounding rock deformation and the plastic zone of surrounding rock, reduce the surrounding rock stress concentration, unilateral pilot tunnel method is better than the other three methods. But in combination with tunnel engineering conditions, considering the construction process and construction period, in actual construction, step method may be used for Huitougou tunnel.