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Designing waterproofing for shield tunnel segments with water expansive materials


Masahiro OHTSUKA1, Toru KOBAYASHI2, Atsushi KOIZUMI3,
1. Tokyo Electric Power Company; 2. Nippon Civic Consulting Engineers Co., Ltd; 3. Waseda University
Proceedings of the JSCE, No. 651/VI-47, pp.61-79. June 2000.

Key words: Shield tunnel, segment lining, waterproofing design, seal, performance-based design methods, waterproofing material test

Background

Shield tunneling is being increasingly used for urban tunnel construction as it safeguards overlying structures. Tunneling depths of urban shield tunnels have recently been increasing, and better performance of the waterproofing materials and capability to withstand higher pressures is required. Waterproofing of such shield tunnels is critical to maintain both the environment of the existing overlying facilities and the shield tunnel itself. However, waterproofing design of shield tunnels is based on experience and past results, and there is no established waterproofing design method.

Research Summary
We carried out many tests of waterproofing materials commonly used for shield tunnels. Hydrophilic materials that expand in contact with water were tested for their sealing performance in situations that actually arise in design, such as "no seal groove provided", "seal groove provided", or "uneven alignment of segments". From the results of the tests, waterproofing mechanisms were better understood. A flowchart for quantitative design of waterproofing materials was developed and a detailed waterproofing design method proposed. Furthermore, an investigation was carried out into the material coefficient ƒÁs taking the variation in properties of the waterproofing material into account, and a design method complying with performance-based design methods was introduced. As a result, quantitative design for waterproofing materials is now possible.

 
 




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