Stray Current Interference from Metro Drainage Cabinet Operation to Nearby Buried Steel Structures

Taking a domestic subway line and its adjacent buried long-haul pipeline as the test objects, the electrical parameters related to the subway structure and pipeline were tested simultaneously under different operating conditions of drainage cabinet, and the influence rule of operating conditions of drainage cabinet on the stray current interference to adjacent steel structures (ballast-bed collection network, tunnel wall structural reinforcement and buried pipeline) was analyzed. The results showed that the extreme value of the current through the drain cabinet was as high as 839.48 A,when the drainage cabinet was in use, especially the grounding grid branch. The suppression effect of drainage cabinets on the rail-to-ground potentials at both ends of power supply interval was inversely proportional to the current flowing through the drainage cabinet, and the negative suppression effect was greater than the positive one. The interference effect of the drainage cabinet on adjacent buried steel structures was mainly reflected in the increase of positive polarization potential deviation, and the increase amplitude was proportional to the current through the drainage cabinet. When the drainage cabinet and OVPD, especially OVPD adjacent to the structure worked together, the positive polarization potential deviation and the negative polarization potential deviation were obviously increased at the same time. The influence range of stray current interference was less than 2 km to tunnel structure reinforcement, and it was greater within 3 km and less outside 6 km to the pipeline.