Construction Technology of Underpinning of Pile Foundations in Water: a Case in Construction of Chengdu Metro

The left tube of the shield-bored running tunnel from Chunxi Road Station to Dongmen Bridge Station on the second line of Chengdu Metro crosses the pile foundations of Dongmen Bridge.In order to ensure the successful boring of the shield,underpinning method is adopted.Countermeasures,such as building cofferdam in water,curtain grouting,dewatering,manual-cut holes and static blasting,are taken during construction,which brings the settlement of the bridge abutments under effective control and ensures the safety of the bridge,the utility lines and the pile foundation underpinning construction.