Numerical parametric study of tunneling-induced joint rotation angle in jointed pipelines

Pipeline-tunnel interaction has attracted increasing research attention recently. Previous studies focused mainly on tunneling-induced deformation in continuous pipelines. In this paper, an extensive numerical parametric study is conducted to investigate the response of jointed pipelines (where joints are simulated as hinges) to tunnel excavation. Prior to the numerical parametric study, the numerical model was verified by centrifuge test results. Parameters considered include ground settlement profile, pipe dimensions, pipe segment length, and soil properties. The maximum and minimum joint rotation angles occur when the tunnel centerline is located directly beneath a joint and a pipe segment center, respectively. When pipe segments are relatively flexible, the joint rotation angle increases rapidly as pipe segment flexural stiffness increases. In contrast, negligible changes are observed in the joint rotation angle for relatively stiff pipe segments when pipe segment flexural stiffness changes. A dimensionless parameter, called relative pipe segment-soil stiffness, is defined to differentiate the response of flexible and stiff jointed pipelines. The relative pipe-soil stiffness and normalized pipe segment length are adopted to predict jointed rotation angles for relatively flexible and stiff pipelines, respectively. Dimensionless plots are developed for directly estimating upper and lower bounds on joint rotation angles due to tunneling.