Tunnel waterproofing practices in China

Abstract

Water ingress in transportation tunnels not only will shorten the durability of concrete lining and reduce the function of establishments in the tunnel, but also will worsen the tunnel surrounding so much that the traffic will be greatly affected. In this situation, therefore, high maintenance costs are compulsory. In many cases, a perfect appearance is strongly recommended to take measures in order to prevent leakage. However, in China, tunnel waterproof requirements and standards for various special uses are considerably different, such that the basis which engineers apply to design in water-control is insufficient. Especially in montanic region, unpleasant geological condition confines engineers in working out more reasonable methods to stop water seepage, even leakage. In this paper, the current waterproofing requirements and measures in different special tunnels adopted in China are reviewed. The limitations of the popular methods in several practical cases applied to prevent water leakage, such as watertight lining, drainage system, as well as grouting, are analyzed at length. Then, some available measures, regarding concrete lining, watertight layer, drainage establishments as well as casting watertight concrete, are proposed, which we think indispensable for tunnel engineering to efficiently control water seepage and even completely prevent water leakage. In the end, to analyze the seepage field in montanic tunnels, the finite element and boundary element coupling analysis method is presented. As an example, the seepage field in Zhenwushan tunnel of Chongqing is simulated. The calculation results coincide with the in-situ data well, and provide credible evidence for the waterproof measures which will be taken in that tunnel project. The method presented in this paper will save expenditures for surveying measures and will enable more reasonable and reliable waterproofing measures to be taken. (C) 2000 Published by Elsevier Science Ltd. All rights reserved. | Water ingress in transportation tunnels not only will shorten the durability of concrete lining and reduce the function of establishments in the tunnel, but also will worsen the tunnel surrounding so much that the traffic will be greatly affected. In this situation, therefore, high maintenance costs are compulsory. In many cases, a perfect appearance is strongly recommended to take measures in order to prevent leakage. However, in China, tunnel waterproof requirements and standards for various special uses are considerably different, such that the basis which engineers apply to design in water-control is insufficient. Especially in montanic region, unpleasant geological condition confines engineers in working out more reasonable methods to stop water seepage, even leakage. In this paper, the current waterproofing requirements and measures in different special tunnels adopted in China are reviewed. The limitations of the popular methods in several practical cases applied to prevent water leakage, such as watertight lining, drainage system, as well as grouting, are analyzed at length. Then, some available measures, regarding concrete lining, watertight layer, drainage establishments as well as casting watertight concrete, are proposed, which we think indispensable for tunnel engineering to efficiently control water seepage and even completely prevent water leakage. In the end, to analyze the seepage field in montanic tunnels, the finite element and boundary element coupling analysis method is presented. As an example, the seepage field in Zhenwushan tunnel of Chongqing is simulated. The calculation results coincide with the in-situ data well, and provide credible evidence for the waterproof measures which will be taken in that tunnel project. The method presented in this paper will save expenditures for surveying measures and will enable more reasonable and reliable waterproofing measures to be taken.