However, if the soil is coarse, once the pipe is displaced, soil would also move, and no gap occurs between the pipe and soil. Therefore, there will still be a pressure on top of the pipe body because of the overburden soil (Fig. 3b). So, in modeling the first case, interactions should be defined so as to consider the detachment of pipe-soil nodes.
Pipe-soil interaction is not clearly explained in the original article, and it is just mentioned that interaction is defined as a finite sliding. The authors should discuss the pipe-soil interaction in more detail and explain which friction coefficient was used for tangential friction and how the relative slippage and the separation between the pipe and soil were considered.
As shown in Fig. 4, after the foundation settlement, the displacement would be transferred to the pipeline, causing the pipeline to be divided into four sections: unaffected part, transition part, bent part and straight part. In fact, if a deflection occurs, these sections would appear as well. In the numerical model, the length of these sections can be calculated by solving the governing equations.
Forces Causing Thrust:
1- Static forces (Internal pressure)
2- Dynamic forces (Fluid velocity)
1- Static forces (Internal pressure)
2- Dynamic forces (Fluid velocity)
Restraining Techniques:⤵️
1- Thrust blocks
2- Restrained joint system
3- Tie rods
4- Combined systems
1- Thrust blocks
2- Restrained joint system
3- Tie rods
4- Combined systems