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城市轨道交通直流牵引系统杂散电流可能导致钢轨、道床钢筋、结构钢筋和地下金属管线等发生不同程度的腐蚀,杂散电流分布及对腐蚀定量影响目前国内外还缺乏研究。针对目前规范中典型的3种走行轨对地过渡电阻状态:15?·km(新建线路验收限值)、3?·km(运行线路限值)和0.5?·km(不良状态),数值计算对比了机车距离变电所负极距离0.5、1.0、1.5、2.0、2.5和3.0 km 6种位置时沿线钢轨对地电位分布以及钢轨和杂散电流分布。研究结果显示:走行轨对地电阻越小,钢轨泄漏的杂散电流越大。机车在距离牵引变电所负极越远的位置运行时,沿线钢轨的和排流网上的最大杂散电流密度以及沿线钢轨对地电位越大。土壤电阻率为100?·m,走行轨对地过渡电阻为0.5?·km情况下钢轨最严重部分损失占33%,年腐蚀量可达203.62 g/m。该研究为城市轨道交通杂散电流危害定量评估影响提供了依据,清晰地反映了走行轨对地过渡电阻工程控制的必要性。
Stray current of DC traction system in urban rail transit may lead to different degrees of corrosion such as railroad track, steel bar bed, structural steel bar and underground metal pipelines, stray current distribution and quantitative impact on corrosion. At present, there is still a lack of research at home and abroad. In view of the typical resistance transition state of the three types of orbit to ground in the current codes, 15? Km (new line acceptance limit), 3? Km (operating line limit) and 0.5? Km (bad condition), the numerical calculation The rail-to-ground potential distribution and the rail and stray current distribution along the line from 0.5 to 1.0, 1.5, 2.0, 2.5 and 3.0 km from the locomotive to the negative pole of the substation were compared. The results show that the smaller the earth-rail resistance is, the larger the stray current is. When the locomotive runs away from the negative pole of the traction substation, the maximum stray current density along the rail and draining net along with the greater potential of the rail along the rail. Soil resistivity is 100? M, rail transit to ground transition resistance is 0.5? Km case, the most serious part of the rail loss of 33%, the annual amount of corrosion up to 203.62 g / m. The study provides the basis for the quantitative assessment of the stray current hazards in urban rail transit, and clearly reflects the necessity of engineering control of the transit rail to ground transition resistance.