Objective Static pressure pile construction exerts squeezing effects on the surrounding soil layers and causes changes in pore water pressure over a period of time, thereby affecting the displacement and deformation of existing metro tunnel structures. Analysis of this process is helpful for standardizing control methods for projects adjacent to existing metro tunnel structures.

Method Taking the Yushan Square Station - Zhujiang Rd. Station shield tunnel interval on Suzhou Rail Transit Line 11 as a case study, the project overview is introduced. A single row of static pressure piles on one side is arranged. Under the effects of soil squeezing and excess pore water pressure, multiple working conditions are established based on different horizontal and vertical distances between the piles and the tunnel. A finite element numerical analysis is conducted to obtain the response results of tunnel displacement and deformation under each working condition. Finally, by superimposing the effects of soil squeezing and excess pore water pressure, the displacement and deformation of the metro tunnel under the identical working conditions and at the same construction stage are analyzed, and the influence patterns of static pressure pile construction on the displacement and deformation of existing metro tunnels are summarized.

Result & Conclusion  The horizontal displacement of existing tunnels is mainly dominated by soil squeezing effect, while the vertical displacement is mainly caused by excess pore water pressure. The horizontal influence range is approximately 40 m, and the vertical influence depth is about two-thirds of the pile length. The horizontal deformation of tunnels in response to construction is greater than the vertical deformation. The maximum horizontal displacement occurs during the dissipation stage of excess pore water pressure, and its occurrence time is delayed with increasing pile-tunnel clear distance and advanced with increasing tunnel burial depth.