高寒冻融环境下隧道结构服役性能预测模型

为分析高寒大温差冻融环境对公路隧道衬砌结构长期服役性能的影响, 采用现场测试方法得到了姜路岭隧道洞口温度变化规律, 基于室内冻融循环试验拟合了冻融环境下衬砌混凝土力学性能劣化计算公式, 应用荷载结构法建立了高寒冻融环境下衬砌结构服役性能的时空预测模型。研究结果表明: 铺设厚度为5cm、导热系数为0.03 W·(m·℃)^-1的保温层后, 姜路岭隧道1年内经历的等效室内冻融循环次数从8下降为0.32;无保温层且混凝土饱水条件下, 5、10、15、20年后拱脚处截面安全系数相对于刚服役时分别降低了0.6%、23.7%、41.1%、69.8%, 二次衬砌服役20年后安全系数已不能满足结构承载的要求; 铺设厚度为5cm、导热系数为0.03 W·(m·℃)^-1的保温层后, 二次衬砌服役100年后安全系数仍能够满足承载要求。可见冻融循环的剧烈程度对衬砌结构长期服役性能影响显著, 保温层能有效改善混凝土的冻融环境。

Service performance prediction model of tunnel structure in alpine freezing-thawing environment

In order to analyze the influence of alpine freezing-thawing environment with large temperature difference on the long-term service performance of highway tunnel lining structure, the temperature variation law of Jiangluling Tunnel portal was obtained by field test method, the calculation formula for the mechanical property deterioration of lining concrete in freezingthawing environment was obtained based on indoor freezing-thawing cycle test, and the load structure method was used to establish the spatial and temporal prediction model of service performance for lining structure in alpine freezing-thawing environment. Research result shows that after the insulation layer with the thickness of 5cm and the thermal conductivity of 0. 03W·(m·℃)-1 is laid, the number of equivalent indoor freezing-thawing cycles for Jiangluling Tunnel in one year decreases from 8to 0.32. When there is no insulation layer and concrete is saturated, 5, 10, 15, 20 years later, the safety coefficients of arch foot section respectively decrease by 0.6%, 23.7%, 41.1%, 69.8% compared to the original service time. After 20 years of service, the safety coefficient of second lining cannot meet structure load requirement. After the insulation layerwith the thickness of 5cm and the thermal conductivity of 0.03W·(m·℃)-1is laid, the safety coefficient of second lining still meet the load requirement after 100 years of service. The severe degree of freezing-thawing cycles has significant influence on the long-term service performance of lining structure, and the insulation layer can effectively improve the freezing-thawing environment of concrete.