Numerical modeling of the effect of moisture migration and evaporation on the temperature of internal wall surfaces in tunnels

Abstract

Tunnels are vulnerable to water infiltration. Water infiltration can cause significant damage to tunnes structure. Tunnel linings, concrete structures, and equipment can be adversely affected over time by water infiltration. Water leaks are most commonly caused by construction and expansion joints (Ji et al., 2012). Locating and characterizing the water infiltration associated with joints is a major concern for the safety and maintenance of tunnels. The presence of water in concrete influences its heat exchange properties and temperature. The influence of heat exchanges can be detected by infrared thermography, a non-destructive imaging method that allows the temperature of a surface to be determined from a distance. Thermal imaging can locate and characterize water infiltration in different structures such as tunnels. As of yet, no quantitative method has been developed to measure infiltration in tunnels through the use of infrared thermography (M’nasri, 2020). In this study, the effect of variation in relative humidity, air temperature, water temperature, convection coefficient, and material permeability on concrete temperature was investigated using a numerical model. A parametric study was conducted with the numerical model of an expansion joint. The numerical model was developed based on the physical model that was constructed by M'nasri (2020). The numerical model was validated with the temperatures measured with the physical model. The good correlation obtained with the respective test cases shows that the model can be applied to evaluate the thermal behavior of the tunnel walls. The results show the importance of relative humidity and environmental conditions on the temperature of the wall surface inside the tunnel. Joints in a higher relative humidity environment will have a higher temperature because of the slower rate of evaporation. The temperature anomaly of a leaking joint varies with the difference between the water and air temperatures. For joint permeability values between 1×10-17 m2 and 1×10-15 m2 , the environmental conditions control the temperature anomaly. For permeability greater than 1×10-13 m2 , the temperature anomaly is controlled by groundwater temperature. The temperature decrease at the joint with an increase in convection coefficient. With an increase of the temperature difference between air and water, the temperature anomaly associated with a leaking joint also increases. The results show an increase in permeability causes the joint surface to experience a higher temperature drop. For higher relative humidity, it is difficult to detect the temperature variation associated to close permeabilities.

Date	22 Mar 2023
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	François Duhaime (Supervisor)