关键词: 圆形顶管隧道, S型空间曲线顶管, 管道应力, 施工参数, 现场监测, 数值模拟

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 pipesoil contact stress of the pipeline is analyzed. A threedimensional 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 Sshaped 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 pipesoil 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 pipesoil 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.