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Evaluation of the long term durability of water expansive sealing products


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.707/VI-55, pp.101-110. June 2002.

Key words: Shield tunnel, segment lining, waterproofing design, water expansive sealing material, durability, waterproofing material test


Background

Water expansive sealing materials for waterproofing shield tunnels were developed in the early 1980s. They had performed well for up to about 20 years, but there was no assurance of long term durability, no method of testing durability, and no criteria for evaluating sealing efficacy.

Research Summary
The research focused on the waterproofing function required from sealing materials and set durability evaluation criteria. Eleven criteria were proposed for evaluating the required durability of sealing materials, and an investigation into the mechanisms of the waterproofing function of water expansive sealing materials was carried out. A temperature accelerated durability test was proposed and a method of setting the appropriate test temperature in this test was developed. It was concluded from the results of tests carried out that the waterproofing performance of rectangular water expansive seals based on natural rubber and urethane materials commonly used for sealing could be maintained for at least 30 years. This research has equipped us with the technical know how for quantitative incorporation of waterproofing materials into design with regard to durability.

 
 




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