Deformation Response of a Pipeline to Nearby Deep Foundation Pit Excavation: Numerical Simulations and Field Tests

Abstract

Deep foundation pit excavation (DFPE) for metro stations in soft layers can cause strata deformation, impairing the safety and performance of nearby existing structures. This paper aims to explore the impact of DFPE on an adjacent oil pipeline using numerical simulations and field tests. Using the project of Xinxingcun Station of Tianjin Metro Line 4 in China as a case study, two approaches of layered excavation (LE) and bench excavation (BE) are proposed for DFPE. The deformation induced by the two approaches was analyzed using the FE method. The maximum vertical settlement of the oil pipeline caused by LE was 8.1 mm, compared with the maximum vertical settlement of 12.5 mm caused by BE. In practice, LE was selected as the construction scheme for the DFPE in Xinxingcun Station. Some field measurement work on pipeline deformation was conducted, and the results were in good agreement with the numerical simulation. Lastly, the change pattern in the pipeline-soil gap was studied. The angle of the position with peak gap width increased from 25° to 110°.