ISSN 2096-4498

   CN 44-1745/U

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Tunnel Construction ›› 2022, Vol. 42 ›› Issue (8): 1375-1385.DOI: 10.3973/j.issn.2096-4498.2022.08.006

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Stress Analysis of SShaped Space Curve Circular Pipe Jacking of a Power Tunnel in Ningbo, China

XU Youjun1, 2, 3, HAN Zhiqiang1, 2, 3, *, ZHANG Chao1, 2, 3, MENG Yixin1, 2, 3, GAO Shenglei4   

  1. (1.School of Civil Engineering,Inner Mongolia University of Science and Technology,Baotou 014010,Inner Mongolia,China;2.Academician and Expert Workstation of Mine Safety and Underground Engineering,Inner Mongolia University of Science and Technology,Baotou 014010,Inner Mongolia,China;3.Urban Underground Engineering Technology Research Center of Colleges and Universities in Inner Mongolia Autonomous Region,Inner Mongolia University of Science and Technology,Baotou 014010,Inner Mongolia,China;4.Beijing Municipal Construction Group Co.,Ltd.,Beijing 100079,China)

  • Online:2022-08-20 Published:2022-09-09

Abstract: To investigate the changes of structural load applied to pipe jacking in the process of Sshaped curve jacking, the influence of construction parameters of Ningbo electric power pipe jacking tunnel on the circumferential and longitudinal reinforcement stress and pipesoil contact stress of the pipeline is analyzed. A threedimensional numerical simulation is conducted to verify actual measurement and expand the multicondition simulation. The results reveal the following: (1) The stress of the circumferential reinforcement is distributed unevenly and is greatly affected by grouting pressure but less affected by machine turning. The top and bottom of the pipe are subjected to tension on the exterior and compression on the interior, whereas the pipe waist is subjected to tension on the interior and compression on the exterior. The longitudinal reinforcement stress is mainly affected by the jacking force. On the Sshaped curve, the pipe waist stress fluctuates alternately; the pipe bottom is subjected to tension on both the interior and exterior, whereas the other parts of the pipe are subjected to tension on the exterior and compression on the interior. (2) The uneven pipesoil gap induced by curved jacking results in uneven grouting pressure. Because deviation correction is applied, the pipeline lies at the bottom right of the mud sleeve. The measured pipesoil contact stress on the left is the largest, followed by that on the top and bottom, and that on the right is the smallest; the simulated and measured data show identical trends (i.e., the stress is distributed unevenly, and machine turning has less effect on the top and bottom of the pipe but a great effect on the pipe waist). (3) The extended simulation shows that when the buried depth and slope of the pipe are large, the stress at the top and bottom of the pipe wall shows clear variations. By selecting an appropriate increase in grouting pressure, the symmetry and evenness of the pipe wall stress can be improved. Large corrections should not be applied for horizontal deviation to avoid stress concentration in the pipe. Increasing the jacking force cannot cause stress redistribution, and the longitudinal stress increases slightly.