浅埋隧道拱上明作拱下暗挖施工技术研究

Construction Technology of Open Excavation on the Arch and Underground Excavation Under the Arch of Shallow Buried Tunnel

浅埋隧道一般指上部覆盖层厚度不足隧道洞径2倍、开挖后将承受全部覆盖层荷载的隧道,施工极易造成隧道塌方等安全事故。针对隧道浅埋地段施工难度大、进度缓慢且危险性较大的技术难题,以南崇铁路项目笔架岭一号隧道工程为依托,综合对比分析明挖法、暗挖法与盖挖法后选择相对较优的盖挖法,并结合工程实际对传统盖挖法进行优化改进。优化后方案采用拱上明作、拱下暗挖的施工方法,规避了浅埋段隧道开挖施工塌方风险,解决了浅埋大断面隧道施工一系列技术难题。经监测隧道地表下沉、净空收敛等均在可控范围内,取得良好的经济效益和社会效益。

Shallow buried tunnel generally refers to the tunnel whose upper overburden thickness is less than 2 times the tunnel diameter,and will bear all the overburden load after excavation.It is very easy to cause safety accidents such as tunnel collapse during construction.In view of the technical problems of difficult construction,slow progress and great danger in the shallow buried section of the tunnel,relying on the Huangniuling No.1 tunnel project of Nanning-Chongzuo Railway,the relatively superior cover excavation method was selected after comprehensive comparative analysis of the open excavation method,the underground excavation method and the cover excavation method,and the traditional cover excavation method was optimized and improved according to the actual engineering.The optimized scheme adopts the construction method of open excavation on the arch and underground excavation under the arch,which avoids the collapse risk encountered in the excavation of shallow buried tunnels,and solves a series of technical problems in shallow buried tunnel construction with large section.Through monitoring,the tunnel surface subsidence and net space convergence are within the controllable range,and good economic and social benefits have been achieved.