Effects of groundwater table on buried pipeline response to a surface explosion

Abstract

Groundwater table is a fluctuating factor changing soil structure and affecting pipes' response to any load, such as an explosion. After validation with the results of previous studies, several numerical models were elaborated with ten different groundwater levels and two states of 1. Empty, 2. Pressurized for a buried pipe to investigate this for an explosion load. These simulations were solved by a Finite Element Method (FEM) solver. This research only studies the effects of non-cohesive soils and neglects the semi-saturated part of the soil for simplicity. The pipe's effective stress and plastic strain in each scenario were studied. The results state that the most critical scenario is when the water table is around the pipe crown, whether the pipe is empty or pressurized, with considerable excess stress compared to the absence of groundwater table. The deformation mode is also hugely affected by the water table, changing from local, forming a dent, to non-local. The internal pressure of the pipe also considerably reduces the pipe stresses and strains whether the surrounding soil is saturated or dry. Such results are certainly impactful in efficiently designing buried pipelines, which most existing guidelines and codes have not considered.