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Analyses of the Sloughing of Tunnel Portal of Yichang-Wanzhou Railway and Its Treatment |
ZHANG Min-qing1, HUANG Hong-jian2, MIAO De-hai3, TIAN Si-ming3 |
1.China Railway Tunnel group Co. Ltd., Luoyang, Henan 471009 China; 2. Yichang-Wanzhou Railway Construction Headquarter of MOR, Enshi, Hubei 445000, China; 3. China Railway Siyuan Survey and Design Group Co., Ltd, Wuhan, Hubei 430063, China |
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Abstract Research purposes: Yichang-Wanzhou railway has 159 tunnels and 150 tunnel portals. Sloughing had happened to 9 tunnel portals during the construction. The analyses of the cause for the sloughing and its treatment are made for purpose of providing reference to the similar construction.
Research conclusions: The sloughing of the tunnel portal is not only related to the geological reason, but also to the unfaithful reconnaissance and unchanging the design scheme timely. Nowadays the main causes for the sloughing of tunnel portal are that the construction is not conducted according to the design, the construction scheme is not changed timely, the construction method is not suitable and the monitoring is not done on time. For the sloughing of tunnel portal, the following measures should be taken; the anchor bolt and steel gridding and spurt concrete are used if the thickness of the soft rock is less than and equal to Sm, the steel-pipe pile and grouting are adopted if the thickness of the soft rock is 5-10m, and the anti-slide pile should be adopted if the thickness of the soft rock is greater than 10m. At the same time, it is necessary to lay the secondary lining to the tunnel outside and tunnel portal.
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Received: 23 November 2007
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[1]JTG D70-2004,公路隧道设计规范[S].
[2]关宝树.隧道工程设计要点集[M].北京:人民交通出版社,2003.
[3]中铁隧道集团技术专家委员会.隧道防坍技术[C].洛阳:中铁隧道集团有限公司,2004.
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