复杂环境下隧道拱顶外露地表暗挖施工技术

Subsurface Excavation Construction of Tunnel Vault Exserting Ground Surface in Complex Environment

某隧道进口端受地形限制,有50m长拱顶露出地表0.8m,且地表有军工设施及厂房,施工环境极其复杂。基于以上背景,提出一种适用于复杂环境中的隧道拱顶外露地表的暗挖施工技术,即裸露拱盖法施工,并对其关键施工技术进行了详细阐述。复杂环境裸露拱盖法关键工序为:通过预加固和后加固措施严格控制围岩和支护变形;分三台阶预留核心土开挖,并及时使初期支护封闭成环;严格控制施工步距。实践证明,提出的裸露拱盖法可实现零埋深或负埋深的隧道暗挖施工,在减小征地面积和边坡防护量的同时,解决了地表上方军工设施迁建周期长的难题。

Limited by the topography,the vault of a tunnel is 0. 8 m above the surface about 50 meters.Moreover,the military facilities and factories on the ground surface make the construction environment more complex. Based on the background above,a construction technology for subsurface excavation suitable for the tunnel vault exposed surface in complex environment is put forward,namely the bare-arch cover method,and the key construction techniques are expounded in detail. Bare-arch cover method in the complex environment has three key processes： to strictly control the deformation of surrounding rock and supporting through the pre-reinforcement and post-reinforcement measures; to excavate divided into three benches and reserve core soil,and timely enclose the primary support; to strictly control the construction step. Practice has proved that the bare-arch cover method can be applied to the tunnel of zero buried depth or negative buried depth,it can solve the problem of the long cycle of military facilities relocation,meanwhile,slope protection and land area are reduced.