Numerical Investigation of Pipeline Responses to Tunneling-Induced Ground Settlements in Clay

Abstract

Tunnel excavation causes stress changes in the ground, leading to soil movements that may affect the safety and serviceability of existing pipelines. Although the tunnel-soil-pipe interaction has attracted increasing research attention, previous studies primarily focused on the responses of existing pipelines due to tunneling in sand. In this study, an extensive numerical parametric study with 540 numerical runs is conducted to investigate the effects on existing pipelines due to tunneling in clay. Soil responses to uplift and downward pipe-soil relative movements are explicitly simulated. Parameters considered in the tunnel-soil-pipe interaction include ground settlement profile, pipe dimension, material properties, pipe burial depth, and undrained shear strength. A dimensionless plot of relative pipe-soil stiffness and the ratio of maximum pipe curvature to ground curvature are developed to directly estimate pipeline curvature due to tunnel excavation in clays. When the relative pipe-soil stiffness is less than 1×10-4, the existing pipeline deforms with tunneling-induced ground settlement. The existing pipeline is relatively rigid when the pipe-soil stiffness is larger than 10.