1. Centrifuge modeling of the influence of joint stiffness on pipeline response to underneath tunnel excavation
- Author
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Shi, Jiangwei, Chen, Yonghui, Lu, Hu, Ma, Shaokun, and Ng, C.W.W.
- Subjects
Pipe lines -- Design and construction ,Joints (Engineering) -- Mechanical properties ,Tunneling -- Methods ,Earth sciences - Abstract
Any tunnel construction inevitably causes differential soil movements, resulting in additional adverse effects on existing pipelines. Although there are many jointed pipelines in practice, previous studies commonly simplified existing pipelines as continuous structures. In this study, centrifuge tests were designed and conducted to investigate the influence of joint stiffness on pipeline response due to tunnel excavation. Along the longitudinal pipeline direction, upward and downward pipe-soil relative movements were identified. Because of relatively flexible joints causing a reduction in the pipeline flexural stiffness, tunneling-induced maximum settlement in the jointed pipeline was much larger than that in the continuous pipeline. Tunnel excavation caused bending moment in the continuous pipeline only, while bending moment and joint rotation occurred simultaneously in the jointed pipeline. As a result of joint rotation, tunneling-induced maximum bending strain in the jointed pipeline was less than 42.4% of that in the continuous pipeline. If a jointed pipeline is assumed as a continuous structure, tunneling-induced pipeline settlement is underestimated, while bending strain is grossly overestimated. All the centrifuge test results were adopted to verify the validity of calculation charts for estimating tunneling-induced maximum bending strain and joint rotation in existing pipelines. Key words: centrifuge modeling, tunnel-pipe interaction, joint stiffness, bending strain, joint rotation angle Toute construction de tunnel provoque inevitablement des mouvements de sol differentiels, ce qui entraine des effets negatifs supplementaires sur les pipelines existants. Bien qu'il existe de nombreux pipelines articules dans la pratique, les etudes precedentes ont generalement simplifie les pipelines existants comme des structures continues. Dans cette etude, des essais en centrifugeuse ont ete concus et menes pour etudier l'influence de la rigidite des joints sur la reponse du pipeline due a l'excavation du tunnel. Le long de la direction longitudinale de la canalisation, des mouvements relatifs de la canalisation et du sol vers le haut et vers le bas sont identifies. En raison des joints relativement flexibles qui entrainent une reduction de la rigidite a la flexion du pipeline, le tassement maximal induit par le tunnelage dans le pipeline joint est beaucoup plus important que dans le pipeline continu. L'excavation du tunnel provoque un moment de flexion uniquement dans la canalisation continue, tandis que le moment de flexion et la rotation du joint se produisent simultanement dans la canalisation articulee. En raison de la rotation des joints, la deformation maximale en flexion induite par le creusement de tunnels dans le pipeline joint est inferieure a 42,4 % de celle du pipeline continu. Si un pipeline articule est considere comme une structure continue, le tassement du pipeline induit par le tunnelage est sous-estime, tandis que la deformation en flexion est largement surestimee. Tous les resultats des essais en centrifugeuse sont adoptes pour verifier la validite des tableaux de calcul pour l'estimation de la deformation maximale en flexion et de la rotation des joints induites par le creusement de tunnels dans les pipelines existants. [Traduit par la Redaction] Mots-cles : modelisation de la centrifugeuse, interaction tunnel-tuyau, rigidite de l'articulation, deformation par flexion, angle de rotation de l'articulation, Introduction In congested urban areas, it is not uncommon to construct new tunnels adjacent to underground pipelines. Any tunnel construction inevitably causes differential soil movements, resulting in additional adverse effects [...]
- Published
- 2022
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