Long-term continuous in-situ monitoring of tunnel lining surface temperature in cold region and its application

Abstract

In-situ monitoring of tunnel lining surface temperature is the basis for deciding the measures, distribution and parameters of freezing-proof. To overcome the deficiencies in timing frequency of the previous monitoring, an automatic recorder is invented to adapt to low temperature environment and record the lining surface temperature of Hongfu tunnel every hour for nearly two years. With the measured data, main results are obtained as follow: annual temperature changes nearly in a sine form; influenced by the air flow inside the tunnel, temperature changes in a similar way at every monitored section inside. Before tunnel breakthrough, the further the section is from the two ends of the tunnel, the higher the average temperature is in the coldest month. And the average temperature of the coldest month is above 0°C when the distance is over 200m. After tunnel breakthrough, the temperature is below 0°C inside the tunnel. The measured data is taken as the boundary condition to simulate the temperature of tunnel lining and surrounding rock with finite element method. The simulation results show that: tunnel lining may freeze and thaw many times in a year; the temperature of tunnel lining and surrounding rock close to lining is below 0°C in the coldest month, and heat transfers into lining from surrounding rock and its maximum heat flux is 36.08w/m2 on the lining surface. Taking the fitted data by sine function as boundary condition will make some error in tunnel lining temperature.