Analytical calculation of blast-induced strains to buried pipelines

The aim of this paper is to introduce a robust methodology for the analytical calculation of strains in flexible buried pipelines due to surface point-source blasts. Following a brief bibliographic overview regarding the characteristics of ground waves produced by surface explosions, a method used to model wave propagation with radial attenuation and spherical front is presented. Strains due to P- and Rayleigh waves, which dominate the waveform generated by an explosion, are accordingly calculated by modeling the pipeline as a three-dimensional (3-D) cylindrical thin shell and ignoring soil–structure interaction. To simplify the design procedure, a set of easy-to-use relations for the calculation of maximum strains and their position along the pipeline axis is supplied. The derived expressions are evaluated through comparison against 3-D dynamic numerical analyses, field strain measurements in flexible pipelines due to a series of full scale blasts, and state-of-practice design methods. Comparisons show that the proposed methodology provides improved accuracy at no major expense of simplicity, as well as the advantage of properly accounting for the effect of local soil conditions.