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| Lining Cracking Mechanism and Treatment Measures at Tunnel Portal in Seasonally-frozen Soil Regions |
| ZHENG Bo, WU Jian, GAO Hong-bing |
| (China Railway Southwest Research Institute Co. Ltd, Chengdu, Sichuan 611731, China) |
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Abstract Abstract：Research purposes： In recent years, lining cracking in winter and water leaking during spring thawing period have occasionally occurred at portal sections of either short tunnel or long tunnel, especially in high-latitude seasonally-frozen regions of China′s northwest and northeast, it seriously affected the tunnel structure and operation safety. Taking the ZEST tunnel of a railway line in northeast region as an example in this paper, the mechanism of lining cracking in winter and water leaking during spring thawing period at tunnel portal section are studied by means of field tests and numerical simulation, and based on comparing the different treatment measures, the treatment measures suitable for such type of tunnel is put forward. Research conclusions： (1) The annual frozen period in tunnel area is about 5 months, the extreme annual range of temperature is above 60 ℃ and the annual average temperature is 2 ℃, which is a typical seasonally-frozen region. (2) Because the lining cracking section mainly passes through the silty clay stratum and the water content in surrounding rocks is larger, the main cause of lining cracking is the loading effects of frost-heaving force in surrounding rocks. (3) It is recommended to use the treatment measures of "spraying the insulating layer of 12~13 cm thickness and the fireproof mortar, and laying electric heat tracing cables in both side drains", meanwhile, the anchor bolt reinforcement is adopted for the existing damages of lining structure and the epoxy resin embedded processing is used on lining cracks. (4) After evaluating the effects of different treatment measures for these tunnel diseases, the treatment measures proposed in this paper are quite effective and the problems such as cracking and water leaking of tunnel lining are completely solved.
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Received: 05 April 2017
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2017, Vol. 34 
