Experimental study on rubber-sand geobags for protecting buried pipes against rockfall

One of the challenging problems in mountainous regions is protecting pipelines from impact load due to the rockfall. Rockfall characteristics and impact loading have been studied by many researchers; however, there is still a lack of large-scale studies to investigate protection of the steel buried pipelines against the impact of rockfall. In this study, a series of large-scale physical models were developed to simulate the performance of steel pipe buried in protective and unprotective installations. The protection system was geotextile-made bags filled with rubber-sand mixtures. During the falling mass penetration, a few different crucial design parameters including the impact force, the vertical deformation and the circumferential strains at the crown and springline were investigated. As a whole using geobags with the proposed configuration could delay the contribution of the buried pipe in stress bearing, provide more flexible interactions between falling mass, trench soil and the buried pipe, successfully detour the vertical stress to the sides of the pipeline, change the deflection mode to a sort of ring deflection, and protect the buried pipe against the impact stress. The results showed that, depending on the rubber content of the mixture in the geobags, the vertical deformation of the buried pipe was considerably reduced between 31 and 62%.