A novel geofoam-geogrid composite for protecting buried pipelines against blast loads

This study investigates the performance of a novel geofoam-geogrid composite in mitigating the impact of surface and subsurface blasts on API-× 65 steel pipelines buried 2 m below ground level. A 3D nonlinear finite element method was employed to analyze the effects of blast charges ranging from 2.5–10 kg, with burial depths varying from 20 cm to 1 m below ground level. The influence of the geofoam-geogrid composite on the longitudinal strain and transverse deformation of the pipeline was examined, and the safe standoff distances for varying amounts of TNT were compared between reinforced and unreinforced configurations. The results demonstrate that the geofoam-geogrid composite is significantly more effective in protecting pipelines against blast loads. Furthermore, the optimal distance between the geofoam-geogrid composite and the pipeline varied with the blast depth. The safe standoff distance was found to be influenced by the distance of the blast from the pipeline, the blast charge magnitude, and the pipeline's internal pressure. This study introduces, for the first time, the geofoam-geogrid composite as a novel protective solution for pipelines against blast. The geofoam-geogrid composite absorbed up to 5.3% of the blast energy, thereby reducing the energy transferred to the pipeline by 37%.