Coupled Electric-Thermal Damage Model for Lightning Strikes on Buried Pipeline

A coupled electrothermal damage theory model for pipelines is proposed to assess the failure behavior of buried pipelines under lightning strikes. This article considers local thermal nonequilibrium (LTNE) conditions in the soil–water porous medium and the nonlinear characteristics of lightning functions. The calculation results show that the proposed theoretical model has better applicability and accuracy compared with previous models. Parametric analysis shows that under lightning conditions of I_m = 20 kA and T₁/T₂ = 1.2/50 μs, the maximum local temperature of the soil around the pipeline can reach 2160 K, leading to pipeline breakdown. Metal pipelines are shown to be more effective in conducting charges, which alters the electric field distribution in the soil and impacts the formation of plasma channels. The half-peak value of the lightning waveform has a significant impact on pipeline breakdown, and its increase will increase the risk of pipeline breakdown gradually. When considering LTNE conditions, the change in the pipeline surface temperature becomes more pronounced. Under 8/30 and 8/40 μs lightning waveforms, the pipeline surface temperature is approximately 150 and 550 K higher, respectively, compared with the thermal equilibrium conditions. The thermal conductivity and porosity of backfill soil can also affect the thermal damage of lightning-struck pipelines. With clay filling, the highest pipeline surface temperature can reach 2590 K, while with fine sand and coarse sand, it is 1980 and 1510 K, respectively. The pipeline lightning disaster model proposed in this article has engineering significance for the investigation of pipeline lightning failure and disaster prevention mechanisms.