Trenching by Explosives Nearby an Existing Pipeline: Charge Size Charts

Trenching by explosives in the vicinity of an existing pipeline can induce structural damage in the pipeline walls. Charge sizes defined on the basis of optimum trenching effectiveness must be verified on the basis of their impact on the existing nearby pipelines. An effective Structure Medium Interaction (SMI) approach, implemented in a 2-D code, is proposed to model the blast design scenarios. Stress and particle velocity decay is governed by exponential laws calibrated to fit experimental data by means of empirical parameters. Wave propagation filtering through the backfill around the pipeline is obtained by scaling stress and velocity on the basis of standard relationships governing the transmission phenomenon at the boundary. The methodology presented is aimed at producing design charts relating limiting charge to distance, medium, backfill and pipe characteristics. Design charts proposed can be readily used by practicing engineers to verify structural integrity of existing pipelines for the effects of nearby blasts.