| Nowdays,with the rapid development of the economics,the construction of urban rail transit has entered an explosive period,and the network operation of urban subways is gradually improved.Since the rail itself has longitudinal resistance and cannot be completely insulated from the earth,the leakage of stray current is inevitable.In this paper,based on CDEGS software,a multi-interval stray current simulation model including the above-ground traction power supply system and the underground ground grid structure is built through reasonable simplifications and assumptions.By setting the observation line and the observation surface,the scalar potential of each observation point can be simulated and calculated,and the calculation method of the stray current in the ground is introduced.First,a stray current simulation model under uniform geological conditions was built,and the distribution characteristics of stray current and potential in the metal conductor and the ground were analyzed.It includes rail longitudinal current,rail-to-ground potential,longitudinal current of drainage network,ground-to-ground potential of drainage network,stray current and potential distribution in different soil depths,soil stray current and potential distribution at different locations such as trains and traction substations.Based on the above model,the subway stray current simulation model under complex geological conditions such as transverse fault geology,longitudinal fault geology,oblique fault geology,hidden river environment and karst cave environment is built by using the rich soil types of MALZ module.The distribution characteristics of stray current and potential in the ground under different geological conditions are simulated and analyzed.Finally,according to the changes of train operation parameters and environment,the influence factors of subway stray current are simulated and analyzed.It mainly includes the influence of the change of driving condition,such as driving position,driving quantity,driving power and the combination of driving conditions,as well as the influence of the longitudinal resistance of rail,the decline of rail insulation performance to the ground,the uneven line parameters,the switching of exhaust cabinet and so on.At the same time,the influence factors of stray current in buried metal are considered,including the buried depth,the resistivity of overlying insulating layer,the switching of discharge rail and the geology of crossing fault.Through the above research,it is found that: compared with the uniform geological conditions,the stray current and potential change under the complex geological conditions,the potential is mainly concentrated in the high resistance soil region,and the stray current is easier to flow into the low resistance area.The existence of karst caves and dark rivers greatly changes the distribution trend of stray current and potential,and the content of stray current in the underground river environment is much higher than that in uniform geological conditions.When the operating conditions change,the combination of train operating conditions has a great influence on the leakage of stray current,and the leakage stray current of adjacent trains is more significant when the adjacent trains are in the same working condition.When the line condition changes,the change of rail longitudinal resistance is an important reason for stray current leakage,so the maintenance and maintenance of rail should be strengthened at ordinary times.When the drainage cabinet is put into use,because the drainage network is directly connected to the negative pole of the traction substation,the stray current in the ground and the stray current in the buried metal increases sharply,so the number of times the drainage cabinet should be put into use should be reduced as much as possible.Compared with the exposed metal,the stray content in the buried metal is smaller,so the insulating layer can reduce the risk of stray current corrosion of the buried metal.This paper mainly studies the distribution characteristics and influencing factors of subway stray current in different geology,which provides theoretical guidance for the treatment and protection of stray current. |
PDF Full Text Request