3F24 ANALYSIS INTO THE STATE OF RAIL CORROSION ACCORDING TO TRACK STRUCTURE IN SUBWAY TUNNELS(Condition Monitoring-Infrastructure)

Abstract

Tokyo Metro Co., Ltd. has 9 lines; total length of the lines is 195.1kilometer. The total length of tunnels is 166.5km, 85% of all lines. Then, rail corrosion occurs in some part of the tunnel and rail brakes happen due to the corrosion in some cases.For the purpose of prevention of rail break, we investigated fully the rail corrosion on the site for 3 years, from 2011 to 2013, by visual inspection and palpation. The investigation section was selected the places where were recognized the existence of many rail corrosion exist.For identifying section where rail corrosion easily occurs, we made a rail corrosion occurring map. In the map, results of the investigation for rail corrosion and data of the rail exchanges are visualized at 25m intervals. Moreover, we set a score of each rail corrosion and summed up scores in the 25m section. Precisely, a point system of rail corrosion state was made. Using the data, we confirmed influence of difference between inner rail and outer rail, between straight line and curved line, and distance between rail and concrete bed on rail corrosion. For all data, following knowledge were cleared. 1. When distance between rail and concrete bed is large, occurrence of rail corrosion is restrained. 2. Rail corrosion easily occur on rail straight line or inner rail with small distance between rail and concrete bed, and placed near river. We have to exchange rails periodically under the condition.