Mitsunori AKUNE

Study on Thrust Estimation model for Pipe-Jacking Method using In-Site data

Mitsutaka SUGIMOTO

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 is the predominant factor of frictional resistance and adhesion around the pipe. Therefore, the conventional model 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. This analysis model was validated using an ideal tunnel including a curved alignment. This study aims to validate the model using an site measured data. 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 confirmed that the proposed analysis model can express the relative distance between the pipe and the ground and the acting earth pressure on the pipe surface due to the ground reaction in pipe-jacking method reasonably. But the calculation by this model shows divergence at the straight alignment and at the jacking thrust applied.

Therefore the followings are recommended as a future research: 1) the proposed model and the input properties are examined so as to obtain stable solution; 2) the algorithm to generate the input data is improved to obtain an 3D tunnel alignment.

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