Modeling of uplift resistance of buried pipeline by geogrid and grid-anchor system

Abstract

This paper presents an experimental and numerical analysis of the uplift resistance of pipelines buried in reinforced soil. The behavior of the system is studied using a set of laboratory experiments. The pull-out forces of some reinforcing pipelines are the most important factors affecting the uplift resistance. Buried elements such as pipelines that have high pressure fluids or are under high temperature need to be reinforced in order to increase their pull-out resistance. One of the efficient methods of reinforcement is increasing the involvement between pipe and soil by using geogrids and anchors. The grid-anchor is a recent method for increasing the pull-out resistance of soil, and is the method used in this study. The digital image correlation or particle image velocimetry (DIC/PIV) method is used for measuring the displacement in the field of experimental mechanism. We also examined the influence of parameters affecting the soil. An experimental study was performed to investigate the uplift resistance of the pipelines buried in sand reinforced with this system. The experimental results demonstrate that, for the pipes with a diameter of 50 mm, the grid-anchor system of reinforcement can increase the uplift capacity 2.4 times compared with the conventional geogrid and 4 times compared with nonreinforced sand. In the numerical modeling, likewise, 23 experiments were back-analyzed using the software FLAC-3D. It became known that experimental tests compare well with the numerical results.