Stack pipe model for pipe jacking method

The pipe jacking method pushes a tunneling machine through concrete pipes ahead of the jacks. The main factors influencing the thrust force are friction around the pipe and face resistance. Both of these forces can be estimated by the analytical or empirical calculation models established by various researchers. So far, most of the models do not consider the overcutting distance; thus, the pipe behavior is still not clarified. Therefore, this paper introduces a developed stack pipe model with the overcutting effect to describe pipe behavior and evaluate the thrust force using the surrounding ground spring model and pipe positioning model with phase analysis in the finite-element method. A simulation of the pipe behavior was carried out to examine the model's validity and performance. As a result, it was found that the developed model can simulate the soil-pipe interaction behavior and the thrust force reasonably well. Furthermore, it can be pointed out that the thrust force is greatly influenced by the developed friction around the pipe and the moment distribution at the cushion.