Site Monitoring Analysis of Influence of Excavation And Construction of a Unsymmetrical Loading Twin-arch Tunnel

摘要

Unsymmetrical loading twin-arch tunnel which has its own characteristics is different from the general separated tunnel. This paper takes a unsymmetrical loading twin-arch tunnel as the background, supervises the tunnel and clears up and analyzes the monitoring data. The results shows: (1) The subsidence of arch crown grows with section excavation, it diminishes gradually and tends to be stable in the initial stage of support and the complete stage of inverted arch. (2) The convergence pre-day of tunnel surrounding rock increases and becomes stable until the lower inverted arch has finished in the effect of unsymmetrical loading and excavation. (3) The surface position of tunnel midline is the most significant position of excavation influence. (4) Unsymmetrical loading makes the lining and middle wall become dislocated, and cracks and peeling phenomenon appears. These conclusions can provide reference for slope design, construction process and site monitoring for unsymmetrical loading twin-arch tunnel under similar conditions.