To investigate the changes of structural load applied
to pipe jacking in the process of Sshaped 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.
XU Youjun
,
HAN Zhiqiang
,
ZHANG Chao
,
MENG Yixin
,
GAO Shenglei
. Stress Analysis of SShaped
Space Curve Circular Pipe Jacking of a Power Tunnel in
Ningbo, China[J]. Tunnel Construction, 2022
, 42(8)
: 1375
-1385
.
DOI: 10.3973/j.issn.2096-4498.2022.08.006
