Rectification of ground water leakage during the Taipei Metro Danshui Line tunnel operation

摘要

It has been more than 20 years since the Taipei Metro Danshui Line of Taipei City was put into commercial operation and, the tunnels and underground metro stations experience structural aging along with possible deterioration of structural components, which can result in water seepage and sand ingress. In an effort to avoid any adverse influences on the metro operation, including possible passenger safety issues and potential damage to adjacent third-party buildings, Taipei Metro conducted a comprehensive maintenance management program including daily inspection patrols. This paper describes a rectification case of sealing underground water leakage using a controlled low pressure continuous grouting technique, the double-packer grouting. The retrofit work was conducted while the metro remains in normal operation with no interruption. Details of the rectification and instrumentation works are described in this paper. As a result of this retrofit work, the strength of the site stratum has been improved considerably, and the potential structural aging process has been delayed with an improved water tightness. Service life of the underground structure is expected to be extended. The double-packer grouting method proved to be adaptable to relevant underground retrofitting projects.