浅埋偏压软岩地层隧道半明拱进洞施工技术研究

厦蓉高速公路龙门隧道左洞洞口浅埋严重偏压段，地质条件差，若采用常规施工方法开挖进洞，需要进行大范围的边坡开挖和防护，施工周期长、成本高，且安全风险极高。基于以上背景，研究出一种浅埋偏压软岩地层隧道半明拱进洞施工技术，该施工方法在减少或不破坏地表的情况下，将隧道衬砌结构外露部分所“缺”围岩以钢筋混凝土结构“弥补”，同时，该施工方法开挖量小，不会对隧道周边围岩产生明显影响。目前，该隧道洞口按照此方法已经施工完毕，实践证明该施工技术是可行的。

Study on Construction Technology of Half Open Arch Tunnel-entering in Shallow Buried and Biased Soft Rock Stratum Tunnel

Left tunnel portal of Longmen tunnel in Xiamen-Chengdu Expressway is in shallow buried and severe bias area; geological condition is poor if adopting conventional open cut method for excavation into tunnel, a wide range of slope excavation and protection is needed, which leads to high and steep slopes and the workload of temporary support in underground excavation is great with long construction period, high cost and great risk of security. Based on the above background, this paper presents a tunnel construction technique of half open arch tunnel-entering in shallow buried and biased soft rock stratum tunnel. This construction method can well adapt under the condition of less destruction or no destruction of the earth’s surface, the"missing"surrounding rock of the exposed part of the tunnel lining structure is made up of reinforced concrete structure; Meanwhile, the construction method has small excavation volume and will not have a significant impact on the surrounding rock of the tunnel. At present, the tunnel portal has been completed in accordance with this method. The practice has proved that the construction technology is feasible which can provide reference for similar projects in the future.