Key Construction Technologies for Super-Shallow Burial Tunnel Portals in Large Cross-section Skewed Tunnels
Factors affecting the safety of the concealed excavation of tunnels are numerous,particularly challenging under adverse geological conditions at tunnel portals.This paper takes the super-shallow buried section of the four-lane large cross-section tunnel portal with steeply inclined strata at Wenfengshan Tunnel#1 as a case study.Ground grouting reinforcement,construction of portal arch sleeves,and installation of ultra-long pipe sheds were employed as entry conditions.The seven-step dual-side wall heading method was used for tunnel excavation,accomplishing the construction of advanced small pipes,followed by large-scale mechanical excavation to minimize disturbances and control the workface distance between steps and the sequential length between the former and latter headings on the left and right,so as to ensure the stability of the rock face in the steeply inclined super-shallow burial section.This approach facilitated rapid small step ring construction,effectively resolving challenges in tunnel entry,achieving early entry goals,and providing robust security for the successful completion of the tunnel.These methods offer valuable insights for similar tunnel construction projects.
large cross-section tunnelskewedsuper-shallow burialconstruction technology
NETL
NSTL
万方数据
