Fragility analysis of gray iron pipelines subjected to tunneling induced ground settlement

Tunnel excavations can cause ground surface settlement which in turn affects the structural integrity of adjacent pipelines. This paper explores the probabilistic risk assessment of gray iron pipes subjected to tunneling. In the beam-on-spring analysis, a modified Gaussian distribution profile was incorporated as displacement-controlled boundary conditions on spring elements. The modeling strategy was evaluated by comparing calculated pipe strains with field and centrifuge experimental measurements, as well as empirical solutions. The calibrated numerical model was then used to perform parametric fragility analyses using a machine learning technique called Lasso Regression to demonstrate the relative importance of various parameters. It has been found that existing pipelines with a smaller pipe diameter and a larger pipe wall thickness buried at a shallower depth in loosely compacted soils with a smaller soil friction angle are less prone to failure due to tunneling induced ground settlement.