28 November 2024
New research reveals how culverts affect frost damage on roads
Frost damage to roads is a significant problem in cold climates. Culverts, used for drainage, can exacerbate this issue by affecting the temperature distribution within the road structure. Karina Tommik at Luleå University of Technology has investigated how airflow and temperature conditions in culverts influence the depth and spread of frost in the surrounding soil.
The research shows that airflow through culverts plays a crucial role in the depth of frost penetration. When the culverts are open and air can flow through them, it leads to deeper frost penetration compared to areas without culverts. The study included field investigations at several culverts of different sizes near Luleå. The results showed that factors such as snow cover and wind affect the temperature inside the culverts, which in turn influences the frost depth.
“Our research shows that airflow through culverts plays a crucial role in the depth of frost. When the culverts are open and air can flow through them, it leads to deeper frost penetration compared to areas without culverts,” explains Karina Tommik.
During the early freezing period, when there is not enough snow to block the ends of the culverts, the airflow through the culvert causes the internal temperatures to follow the external air temperatures. When the culverts are blocked by snow, the internal temperatures stabilize and are less affected by external conditions.
“It is important to understand these processes to design roads that can withstand frost damage. Our work provides new insights that can help improve road construction in cold climates,” says Karina Tommik.
To better understand these thermal conditions, a new model was developed using COMSOL Multiphysics, which couples airflow and heat transfer to simulate thermal conditions inside the culvert. The model, based on field investigations, was divided into scenarios representing unobstructed and snow-obstructed culverts. Frost depth data was used to validate the model's boundary conditions, which were then used to conduct a parametric study on the impact of culvert size on frost depth.
The study concludes that a non-isothermal flow model can effectively determine thermal boundary conditions in culverts and assess the impact of airflow on frost depth. The presence of airflow within the culvert during the freezing period leads to increased frost penetration around the culverts, which increases with larger culvert sizes. However, a sufficiently thick snow cover that blocks the ends of the culvert can inhibit further frost depth progression.
Contact
Karina Tommik
- Doctoral student
- 0920-493996
- karina.tommik@associated.ltu.se
- Karina Tommik
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