期刊
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
卷 46, 期 -, 页码 18-27出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.tust.2014.10.002
关键词
Nanjing Yangtze River Tunnel; Slurry shield; Excavation chamber; Filter cake; Compressed air-support
资金
- National Natural Science Foundation of China [51408191/51278165]
- China Postdoctoral Science Foundation [2014M560388]
- National Program on Key Basic Research Project of China [2015CB057803/2012CB719804]
- Natural Science Foundation of Jiangsu Province [BK2011025]
Shield tunnel construction in a dense strata often encounters malfunction of shield-tunneling machine or abrasion of cutters. Accessing to an excavation chamber under compressed air is a main method to repair and replace worn cutters. And many safety issues such as stability of the excavation face were involved. However, the face stability due to opening an excavation chamber was not fully studied. To overcome this shortcoming, face support scheme and stability analysis were presented in a case history of opening the pressure chamber for a large-diameter (up to 14.93 m) slurry shield tunnel constructed underneath Nanjing Yangtze River. Since most of the damaged cutters were distributed along the edge of cutting wheel, only top 3 m of tunnel face within the chamber needed to be supported by compressed air, and remaining area would also to be supported by slurry pressure. A series of simple primary laboratory tests were carried out to design an optimum slurries mixing scheme to support the tunnel face as accessing to the pressure chamber in the project. The face stability was analyzed in terms of the pressure equilibrium (i.e., internal and external pressures) as well as three-dimensional numerical analysis by adopting properties of soils and filter cakes from laboratory tests. By injecting lower density slurry into the sand to form a stable infiltration zone, followed by using higher density slurry to create a filter cake at tunnel face, compressed air-support system could ensure face stability during maintenance of cutter wheel. The success of applying the mixed slurry and compressed air-support scheme in this project is valuable to shield tunnel constructions in similar ground conditions. (C) 2014 Elsevier Ltd. All rights reserved.
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