Key Construction Technology for Large-spanned Highway Tunnels under Complex Environment

Wansongling tunnel,located in Hangzhou,China,is a large-spanned highway tunnel containing 4 lanes in both directions.Due to the large cross-section,large span,shallow cover,complex engineering geological conditions and complex surrounding environment of the tunnel,there exist great difficulties in the construction of the tunnel.By means of such key construction technologies as ground pre-consolidation performed from inside tunnel,double-side-drift construction method and micro-vibration blasting,the tunnel has been completed safely and successfully and good economic and social efficiency has been achieved.