气候变暖条件下寒区隧道可靠性分析

Reliability of tunnels in cold regions subject to climate warming

气候变暖将对寒区隧道长期稳定性和可靠性产生显著影响,也对寒区隧道工程防灾减灾提出了新课题。为探究气候变暖条件下寒区隧道可靠性的演变规律,以巴哈达坂隧道为对象,建立热力耦合数值模型,研究未来50年青藏高原气温升高2.6℃,3.0℃和4.0℃时,围岩温度场和变形场等的时效变化特点。采用蒙特卡罗法研究隧道可靠性及敏感性的变化规律,并提出增强隧道可靠度的技术措施。研究结果表明:当二次衬砌和保温层厚度分别为5 cm和40 cm时,50年后气温升高2.6℃和4.0℃时隧道可靠度分别为87.5%和82.2%;如果要将50年后隧道的可靠度确保在90%以上,气温升高2.6℃时二次衬砌和保温层的最小厚度为42.3 cm和7 cm,比现有设计提高了6%和40%;而气温升高4.0℃时二次衬砌和保温层最小厚度达到45.2 cm和9 cm,比现有设计分别提高了13%和80%。根据IPCC结论,如果未来50年能将第三极升温控制在3.0℃内,当保温层厚度为8 cm,二次衬砌厚度不小于42.7 cm时,隧道可靠度即可达90%以上。

Climate warming has a serious impact on the long-term stability and reliability of tunnels in cold regions and also puts forward a new topic for disaster prevention and mitigation of such tunnels.In order to determine the evolution law of the reliability of tunnels in cold regions under the condition of climate warming,the Bahadaban tunnel was taken as an example.The thermodynamic coupling numerical model of the tunnel was established,and the temperature and deformation fields of surrounding rocks of the tunnel were all studied for different scenarios where the temperature on the Qinghai-Tibet Plateau was assumed to increase by 2.6 ℃,3.0 ℃and 4.0 ℃ in the next 50 years,respectively.The changing laws of tunnel reliability and sensitivity were studied by the Monte-Carlo method,and the technical measures to improve tunnel reliability were proposed as well.The results show that when the thickness levels of secondary lining and insulation layer are 5 cm and 40 cm,respectively,the reliability of the tunnel is 87.5% and 82.2% when the temperature increases by 2.6 ℃ and 4.0 ℃in next 50 years,respectively.If the tunnel reliability is to be ensured to be more than 90% 50 years later,the minimum thickness levels of secondary lining and insulation layer of is 42.3 cm and 7 cm for the temperature increase of 2.6 ℃,respectively,which corresponds to 6% and 40% increase than the existing design thickness levels,respectively.When the temperature rises by 4.0 ℃,the minimum thickness levels of secondary lining and insulation layer reach 45.2 cm and 9 cm,respectively,which is 13% and 80% higher than the design thickness levels.According to the IPCC report,if the temperature rise of the third pole can be controlled within 3.0 ℃ in next 50 years,the reliability of tunnels can begreater than 90% when the secondary lining is 42.7 cm thick and the insulation layer is 8 cm thick.