Improvement on Thrust Estimation method for Pipe-Jacking Method
Since the conventional model for thrust estimation in pipe-jacking method does not consider the gap between ground and tunnel, the conventional model cannot evaluate the effect of over-cutting, which has strong influence on frictional resistance and adhesion around the pipe. Therefore, it adopts the loosening earth pressure and the thrust reduction coefficient for each ground condition.
To overcome the above problems, the new analysis model has been developed by using full ground spring model that can take over-cutting into consideration. But the calculation by this model shows divergence at a curve with a certain length. This study aims to improve the model so as to obtain stable solution.And the improved model for thrust estimation is examined by verifying the analysis result from the viewpoint of mechanics.
As a result, it was made clear that the proposed analysis model can express the ground displacement distribution and the acting stress on pipe surface due to ground reaction in pipe-jacking method reasonably. Finally, It can be said that the improved analysis model can estimate the thrust in pipe-jacking method.