The influence of geosynthetic reinforcement on the mechanical behaviour of soil-pipe systems

Buried pipes may transport substances that can be harmful to people and the environment. These structures may be subjected to damages caused by soil movements and external interference, such as surcharges and excavations. Different applications of geosynthetics have demonstrated that they can be used to protect buried pipes and to minimize the consequences of pipe burst. This paper discusses results of large scale laboratory tests on a flexible pipe buried in unreinforced and geosynthetic reinforced soils subjected to surface surcharges. The pipes were buried in a cohesionless soil and different types of reinforcements were tested, with a wide range of tensile stiffness values. The results obtained show that the arrangement of the reinforcement enveloping the pipe reduced significantly pipe displacements and deflections. The efficiency of the reinforcement depended on its type and physical and mechanical properties. The open geogrid tested showed less reinforcement efficiency due to the passage of soil particles through its aperture during the tests. A theoretical solution available for pipes in unreinforced soils was extended to the reinforced situation with good agreement between predictions and measurements and showed that the presence of the reinforcement is equivalent to the pipe being buried in a significantly stiffer unreinforced soil.