偏压浅埋隧道洞口施工技术

Construction Technology of the Entrance Section of a Shallow and Unsymmetrical Loaded Tunnel

对于偏压浅埋隧道,由于施工工序的复杂性和围岩应力分布不均匀性,增加了该类隧道的施工技术难度。某隧道进口段围岩破碎、节理发育,上部最小覆盖土层厚度为4.5 m,由于采用了进洞口围岩预加固、台阶法预留核心土开挖、洞内围岩超前加固等施工技术,使得工程顺利完成。

Owing to the complexity of construction process and the non-uniform stress distribution in surrounding rocks of shallow tunnels, the construction technology of them involves difficulties. The entrance section of a tunnel features fractured surrounding rocks with developed joints, the minimum thickness of cover is 4.5m. Construction of the tunnel was successfully accomplished by adopting a series of techniques including advance strengthening of surrounding rocks on the entrance section before boring, excavation by using bench method with the core ground reserved, advance supporting of surrounding rocks for the excavation of main tunnel.