Tunnelling-induced response of buried pipelines and their effects on ground settlements

In urban areas, it is common to construct new tunnels beneath existing buried pipelines. The accurate estimation of the response of pipelines and the overlying ground is of great importance as it is essential for the protection of the pipelines and other facilities. However, this problem is quite difficult as it involves complicated soil-pipeline interaction. In this paper, analytical solutions incorporating the tensionless Pasternak model, which takes full account of the gap formation and the pipeline orientation, have been formulated to estimate the response of the pipeline and the overlying ground. The analytical solutions have been validated by observations from field and model tests, followed by parametric studies to investigate the effects of the gap formation and pipeline orientations. It is found that the formation of a gap beneath the pipeline lowers its deflection and bending moment generated by tunnelling, and a pipeline with a larger intersection angle with respect to the tunnel alignment is anticipated to bear larger bending moment.