Numerical simulation of GFRP blanket effect on reducing the deformation of X65 buried pipelines exposed to subsurface explosion

Blast loads and designing blast load-resistant pipelines have attracted attention because of the multiple terrorist attacks against buried pipelines during recent years. The present investigation is carried out numerically for reducing the deformation of buried pipelines without internal pressure exposed to subsurface explosion. This study presents a novel approach, using Glass Fiber Reinforced Polymer (GFRP) blanket for reducing the deformation of buried pipelines against blast loads. For this purpose, a 3D finite element model (3DFEM) was developed using nonlinear finite element code and combined Eulerian-Lagrangian (CEL) method. JWL equation of state, the ideal gas equation of state, Johnson-Cook plastic model and anisotropic material model were used to simulate the behavior of explosive substances, air, pipe and GFRP Blanket, respectively. In addition, the behavioral model of soil was considered to be Drucker-Prager. The results of this study for the size of crater, the shape of detonation products cloud, maximum longitudinal strain of pipelines and attenuation of blast wave in soil were compared with field results as well as empirical relations and a good concordance was obtained between them. According to our results, a GFRP blanket can significantly reduce pipelines deformation induced by explosion so that the length of damaged zone, cross sectional deformation and the maximum longitudinal strain of pipelines decrease by 59%, 48% and 73%, respectively. Moreover, a GFRP blanket with appropriate thickness is more economic and shows better performance compared with increasing the thickness of pipelines. The results of this study can be used to effectively reinforce constructing or operating buried pipelines against blast load effects.