Study on Maintenance System for Cut and Cover Tunnels Showed Signs of Deterioration by Chloride Attack

EasyChair Preprint no. 4125

Abstract

Tokyo Metro Co., Ltd. operates and maintains tunnels of about 167 km. While maintaining the tunnels, some of them already showed signs of deterioration by chloride attack. Therefore, it was investigated the mechanism of deterioration by chloride attack, features of sections of deterioration by chloride attack, methods of determining repair range and appropriate repair method. Result of the investigations, these structures located close to tidal rivers or reclaimed lands are exposed to high concentrations of chloride ions in leak water. So, repair sections were set according to their positional relationship. Furthermore, as a method of determining the detailed repair range, silver nitrate spraying method was developed. Because of examination of the repair method, it was revealed that the combined use of sacrificial anode construction method and surface impregnation method is appropriate depending on the progress by salt damage. Based on the results, a construction plan was planned. We have been doing construction for 5 years ago. The field test conducted a monitoring survey for 5 and a half years and carried out a chipping out. This report describes the result of salt damage investigation, construction status of repair work and monitoring result.

Keyphrases: chloride attack, chloride induced deterioration, Maintenance Management System, salt damage, subway tunnel

@Booklet{EasyChair:4125,
  author = {Masumi Taguchi and Yuji Morohashi and Takuya Chiba and Hideaki Yamaguchi and Shinji Konishi and Toshiharu Kishi},
  title = {Study on Maintenance System for Cut and Cover Tunnels Showed Signs of Deterioration by Chloride Attack},
  howpublished = {EasyChair Preprint no. 4125},

  year = {EasyChair, 2020}}