Evaluation of the dynamic additional impact about foundation pit construction on the existing adjacent subway station with the PBA method

Abstract

In this paper, relying on the Tianhe East Station project of Guangzhou Subway Line 11, the deformation and mechanical evolution rules about the existing adjacent stations with the pile-beam-arch (PBA) method in the all excavation stages about the new foundation pit is evaluated through numerical calculation method. It was revealed that that the largest displacement about the existing station’s side wall and the middle column reaches 2.1mm and 1.5mm respectively during the excavation about the foundation pit. Due to the impact about construction of the foundation pit, the uplifting phenomenon occurs on the side of the foundation pit, and the maximum uplifting value reaches 0.4mm. When the construction about foundation pit is finished, the whole station floor shows a deformation form of “left lower torsion”, and the largest compressive stresses as well as tensile stresses about the side wall and the bottom plate do not reach the standard limiting value, and the whole is being a relative safe status. With the increase about the excavation depths, the axial forces about the middle column gradually increase to 7016kN, and the incremental axial forces about the middle column after the construction is completed accounts for about 11.7% of the axial force of initial construction. Therefore, the disturbance effect about foundation pit construction on the adjacent station with the PBA method can not be ignored. The research result in this paper may offer some important references for the construction and design of similar cases.