Coupled flow in saturated soil around a vertical grounding rod HVDC considering underground water's action

Abstract

• Coupled fluxes in soils due to current injection into HVDC ground rods are analyzed. • Phenomenon involving the fields of electromagnetism, thermal and hydraulics. • It takes into account the effect of an underground flow. • Results include temperature, velocity and pore pressure in a stratified saturated soil. The phenomenon of coupled fluxes in soils given the injection of current in HVDC (High Voltage Direct Current) ground rods is a multiphysics problem, involving different fields, including electromagnetism, thermal and hydraulics. In some regions where precipitation is intense or due to the presence of an aquifer, the saturated condition of the soil is particularly important for the analysis of the behavior of the environment, based on the active flows. In this study, the water velocity around the ground rod is investigated, as well as the pore pressure and temperature in a transient regime, considering the Joule effect, the performance of the electro-osmotic flow and the action of the underground velocity. Such phenomena are involved by temperature-dependent parameters. The study methodology is based on simulations adopting the finite element method for the coupling of physics in a saturated and stratified soil. The validation of the results for the Joule effect shows a maximum temperature error in the order of 3.3%. As a result, it was possible to infer, through a parametric sweep, the parameters that most favor the increase in temperature, velocity and pore pressure in the medium porous. The results presented serve as a reference for HVDC grounding system designs.