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Geomechanics and Engineering
  Volume 30, Number 4, August25 2022 , pages 383-392

Three-dimensional numerical parametric study of tunneling effects on existing pipelines
Jiangwei Shi, Jinpu Wang, Xiaojia Ji, Huaqiang Liu and Hu Lu

    Although pipelines are composed of segmental tubes commonly connected by rubber gasket or push-in joints, current studies mainly simplified pipelines as continuous structures. Effects of joints on three-dimensional deformation mechanisms of existing pipelines due to tunnel excavation are not fully understood. By conducting three-dimensional numerical analyses, effects of pipeline burial depth, tunnel burial depth, volume loss, pipeline stiffness and joint stiffness on bending strain and joint rotation of existing pipelines are explored. By increasing pipeline burial depth or decreasing tunnel cover depth, tunnelinginduced pipeline deformations are substantially increased. As tunnel volume loss varies from 0.5% to 3%, the maximum bending strains and joint rotation angles of discontinuous pipelines increase by 1.08 and 9.20 times, respectively. By increasing flexural stiffness of pipe segment, a dramatic increase in the maximum joint rotation angles is observed in discontinuous pipelines. Thus, the safety of existing discontinuous pipelines due to tunnel excavation is controlled by joint rotation rather than bending strain. By increasing joint stiffness ratio from 0.0 (i.e., completely flexible joints) to 1.0 (i.e., continuous pipelines), tunneling-induced maximum pipeline settlements decrease by 22.8%-34.7%. If a jointed pipeline is simplified as a continuous structure, tunneling-induced settlement is thus underestimated, but bending strain is grossly overestimated. Thus, joints should be directly simulated in the analysis of tunnel-soil-pipeline interaction.
Key Words
    bending strain; joint rotation; pipeline; three-dimensional; tunnel
Jiangwei Shi, Jinpu Wang: Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, Jiangsu 210024, China
Xiaojia Ji: Intelligent Safe Collaborative Innovation Center, Zhejiang College of Security Technology, Wenzhou 325016, China
Huaqiang Liu: Material and Structural Engineering Department of Jiangsu Water Research Institute, Yangzhou 225000, China
Hu Lu: Shenzhen Polytechnic, No. 7098 Liu Xian Avenue, Nanshan District, Shenzhen, China

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