Abstract:

During the construction of underground Metro station of Chongqing North Railway Station, the running of traffic on the ground and underground parking lot should be guaranteed. The construction technologies for pile foundation underpinning and the Metro station constructed by cut and cover method are proposed. The upper structure of the Metro station is underpinned by temporary piles and the underpinning plate is regarded as cover of cut and cover construction. The temporary support of existing piles and structures and the treatment of connection points between underpinning plate and existing foundation pile and those between underpinning plate and steel pipe column are the construction keys and difficulties of the project. During the pile foundation underpinning construction, Hshaped temporary support system is set according to amount of main beam on existing pile foundations and the adjacent temporary column should be connected in time. During the construction of connection between underpinning plate and foundation pile, part of concrete of foundation of pile foundation is cut off and the rebar is kept. During the construction of connection between underpinning plate and steel pipe column, the pile top rebar reserved is inserted into underpinning plate and then casted. The site monitored deformation results show that the abovementioned technologies are feasible and rational.

Key words: Metro station, pile foundation underpinning, cut and cover method, existing pile foundation, underpinning plate