Numerical Analysis of the Effect of Tunnel Excavation on Underground Pipelines

Accurate assessment of pipeline settlement induced by shield tunneling is important for the safety of underground pipelines. This paper takes the Hangzhou Metro Line No. 1 as background. A three-dimensional model is established using FLAC^3D to investigate the effects of shield tunneling on existing pipelines in transverse and longitudinal directions. In combination with the monitoring data, the effects of the excavation of the left line and right line on pipeline settlement are analyzed respectively. The results show that a transverse pipeline is relatively more dangerous than a longitudinal pipeline. Further parametric studies are made on the transverse pipeline, including burial depth, pipeline material and soil stiffness. The influence of burial depth on pipeline settlement is very small, while the influence of pipeline material and soil stiffness is much greater. When the elastic modulus of a pipeline or soil increases, the maximum and differential settlements of pipelines are obviously reduced. This study can be a reference for the future construction of the Hangzhou Metro.