摘要
为了提高季节冻土隧道的防冻保温性能,常采用铺设聚氨酯类有机保温层的方式以防止围岩冻结,但由于有机材料在冻融循环过程中老化速度快、保温结构设计缺少科学依据等局限性,使得部分隧道在长期运营过程中反复出现冻融病害。以西藏圭嘎拉隧道为研究对象,通过建立热流固耦合计算模型,对现行保温措施的防冻效果进行分析,发现距离洞口一定长度范围内的围岩仍会发生冻融破坏。在隧道运营后第20年2月15日,距洞口5m处断面拱顶围岩的边界温度仅为-0.91℃,并且该关键位置的纵向冻结长度超过500m,严重影响隧道结构的安全。为防止此隧道出现冻害问题,提高其服役能力,拟采用新型无机建筑材料气凝胶毡对隧道的保温结构进行加固,其具有良好的保温、阻燃和耐久性能,并且铺装简便、易于操作。此外通过对不同厚度气凝胶毡条件下的围岩温度场进行多维度分析,确定了最不利时刻气凝胶毡厚度与拱顶围岩关键位置纵向冻结长度之间的关系。研究成果可为圭嘎拉隧道防冻保温优化设计提供技术支持,不仅能保障隧道结构的安全性和稳定性,也能为季节冻土隧道保温结构的设计、施工及维护提供参考依据。
To improve the anti-freeze and heat preservation performance of tunnels in the seasonally frozen regions,the freezing range of surrounding rock is often reduced by laying organic insulation layer such as polyurethane at present. However,due to the rapid aging speed of organic materials during the process of freeze-thaw cycles and the lack of scientific basis for insulation design,some tunnels repeatedly appear freezing-thawing damage during long-term operation. For example,the problems of lining water seepage,hanging ice,tunnel bottle water gushing,pavement freezing,lining cracking,crumbling,spalling,etc. This paper analyzes the effect of current insulating measures by establishing the heat-fluid-solid coupling calculation model,in which the Guigala Tunnel in Tibet is taken as subject investigated,and the result showed that surrounding rock within a certain length of the entrance will still undergo freeze-thaw cycles during the operation period. The boundary temperature of the surrounding rock at the section vault at a distance of 5 m from the entrance was only -0.91℃,and the frozen length of the key point was more than 500 m from the entrance on February 15 th of the 20 th year after the tunnel operation,which seriously affected the safety and stability of the tunnel structure. For the sake of meeting the requirements of antifreeze insulation,a new type of inorganic material—aerogel felt was proposed to reinforce the insulation structure of the tunnel. The material had excellent thermal insulation,flame retardant and durability,at the same time the paving was simple and easy to operate. In order to determine the length and thickness of the aerogel felt to be laid during the Guigala Tunnel operation,the radial and longitudinal temperature of surrounding rock as well as the air temperature in the tunnel were compared in detail under different thickness of aerogel felt. The evolution law of the surrounding rock and the air in the tunnel under different conditions was summarized,and the aerogel felt at the most unfavorable time was determined by data fitting. The relationship between the thickness and the vertical freezing length of the key positions of the surrounding rock was changed exponentially. According to the fitting formula,the relationship between the length and thickness of the aerogel felt should be laid out from the depth of the portal to the depth,which was the best reinforcement and maintenance method for the tunnel insulation structure. This work can provide technical support for the pre-reinforcement design of anti-freezing and insulating in Guigala Tunnel,which not only ensure the safety and economy of the tunnel structure,but also provide a reference for the insulation structure design,construction and maintenance of tunnel in seasonally frozen regions.
作者
李根
李双洋
董长松
杨佳乐
姜琪
LI Gen;LI Shuangyang;DONG Changsong;YANG Jiale;JIANG Qi(State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Road Engineering Safety and Health in Cold and High-Altitude Regions,CCCC First Highway Survey and Design Institute Co.,Ltd.,Xi’an 710065,China;School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)
出处
《冰川冻土》
CSCD
北大核心
2021年第2期510-522,共13页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(41672315)
中国科学院青年创新促进会优秀会员项目(Y201975)
西藏自治区科技计划项目(XZ201801-GB-07)资助。
关键词
季节冻土
隧道
冻融破坏
气凝胶毡
数值模拟
温度场
seasonally frozen soil
tunnel
freezing-thawing damage
aerogel felt
numerical simulation
temperature field
