Jacking technology and monitoring during tunneling under existing metro structures

The PLC hydraulic synchronization control system is used to control the deformation of the existing metro structure during the construction of Dongzhimen Station of Airport Line under the reentry line of Dongzhimen Station of Line 13 of Beijing Metro. Combined with the construction sequences of the drift and pile method, the idea of zoning, phasing, grouping, and staging is adopted to design the overall jacking scheme. The zoning idea refers to the respective calculation of the jacking force according to different structure types of the existing line; the phasing idea means that three phases are divided based on typical construction cases and the control scheme at each phase is respectively made; the grouping idea refers to driving the jacks into different groups and grouping control; the staging idea means the implementation of staged control of the jack force of each group and slow increase of the jacking force to reach the design values. Based on the measured deformations of the existing line, the 3rd phase jacking scheme is executed six times. Practice shows that the PLC hydraulic synchronization control jacking technology may slow the settlement speed and reduce the settlement amount of the existing structures to ensure the safe operation of the existing line, which is an active defense method.