Final Scope

Water infiltration is a common defect encountered in tunnel structures. However, the degree of severity and acceptance criteria associated with tunnel leakage varies depending on tunnel type, geography, weather, and other conditions.  While every structure has a design life, poor control and management of leaks can reduce the level of service.

A huge investment in time and money can be put into combating leaks and the result will typically not yield at a completely water-tight tunnel. Methods of addressing tunnel leakage is hardly one- size-fits-all. The challenge for tunnel owners is to match the appropriate mitigation measure to the relevant leak type and source.

The objective of this research is to document practices used by state department of transportation (DOT) tunnel owners to control tunnel leaks.  The synthesis will document practices for detection, prevention, inspection, diverting, stopping, and accepting tunnel leaks.  Tunnels of concern include, but are not limited to, mined tunnels, bored tunnels, cut and cover tunnels, and immersed tube tunnels.

Information to be gathered includes (but is not limited to):

• Categorization of tunnel leak types (e.g., seasonal, intermittent, at joints, through liner cracks, conduits, freeway cap structures);
• Tunnel types with the greatest leak problems;
• Methods and procedures for detecting tunnel leaks (e.g., routine inspection, thermal imaging, visual inspection, staining, sump pump usage);
• Methods and procedures for mitigating various types of leaks (e.g., caulking, pressure grouting, conduit plugs, joint repair, drainage systems to divert water); and
• Criteria for acceptance of leaks once detected (e.g., impact on other systems, impact on other structures, severity, frequency of occurrence).

Information will be collected through a literature review, a survey of state DOTs, and follow-up interviews with selected agencies for the development of case examples. Information gaps and suggestions for research to address those gaps will be identified.

Information Sources (Partial):

• Tunnel Waterproofing-Available Technologies and Evaluation through Risk Analysis-International Journal of Civil Engineering, Volume 17, Issue 1, 2019.
• Study on Mountain Tunnels Water Reducing Measures and Tunnel Behaviors by Post Grouting-Journal of Japan Society of Civil Engineers, Ser. F1 (Tunnel Engineering) Volume 75
• Grouting Technology in Tunneling-Geomechanics and Tunneling, Volume 6, Issue 3, 2013