Effect of Soil Salt Content on Stray Current Distribution in Urban Rail Transit

In order to study the effect of soil salt content on the stray current distribution in the urban rail transit, a three-layer stray current resistance network distribution model of “rail - drainage net-ground” is established based on the method of resistance network. The mathematical model is established by using the equivalent circuit of micro-element, and the analytical expressions of voltage and current of each metal structure are derived. Then, the simulation model is established with MATLAB/Simulink software, and the simulation results are consistent with the analytical results. A small-scale experimental platform corresponding to the model is built, and the changes of leakage current and the stray current in soil samples with different NaCl content are measured. The experimental results show that the leakage current and stray current in soil samples increases with the increase of NaCl content. Finally, the experimental results are verified by the established simulation model and the simulation results are basically consistent with the experimental results, which proves the accuracy of the experimental results. The research results can provide a theoretical basis for the protection design of subway stray current.