Research on electromagnetic pollution control methods in urban rail transit tunnels

In order to cope with urban population expansion and meet people's daily travel needs, many major cities in my country have newly planned and opened urban rail transit lines with 27.5kV AC power supply. The subway tunnel under the AC power supply system will cause changes in the surrounding ground potential due to the spatial coupling of the AC power and the effect of the stray current. The stray current will cause electrochemical corrosion of the buried metal components around the track and shorten the service life of the metal pipeline., Reduce the strength and durability of the subway reinforced concrete main structure, causing unnecessary equipment and economic losses. The change of the earth potential is reflected in the potential difference between the various substations, which causes the DC bias phenomenon of the neutral point of the transformer. The overall simulation model of the tunnel is established, the electromagnetic pollution in the tunnel is calculated, and the influencing factors and influence rules of the induction voltage of the metal structure in the tunnel are obtained. From the two aspects of ground coupling and electromagnetic coupling, the scheme of structural reinforcement, drainage network and reflux line is found.