Pile Active Underpinning of Existing Building Foundation with Undercrossing Shield Construction

Abstract

Undercrossing shield construction of a subway, the tunnel vault is about 3.0m away from the foundation pile tip of the existing building. In order to analyze the influence of shield undercrossing construction on the existing building and the influence of the existing building load on the tunnel structure, the calculation and analysis are carried out for the existing foundation forms, foundation reinforcement into raft, addition of equal length piles and increase of unequal length piles. Using the method of foundation reinforcement into raft foundation and long pile tip exceeding 0.5m below the tunnel floor can transmit the load of the upper building structure to the soil layer below the tunnel floor and reduce the load of the tunnel roof, thereby achieving the underpinning effect. According to the allowable deformation value of existing building, allowable internal force of segment and allowable deformation value of segment, using this underpinning method can meet the requirements of the various of allowable values of existing building, tunnels, etc.