Calculation method for thickness of discontinuous boundary layer of engineering pavement

The boundary layer is a buffer layer of water and heat exchange between the atmosphere and permafrost. Based on the atmospheric boundary layer and heat transfer theory, we established a method for determining the boundary layer thickness of engineering pavement (asphalt and sand pavement) in permafrost region. The boundary layer can be divided into the Boundary Layer Above Surface (BLAS) and the Boundary Layer Below Surface (BLBS). From in-situ monitoring data, the thickness of BLAS was determined through the laminar thickness, and the thickness of BLBS was determined through ground temperature, the heat conduction function, and the mean attenuation function (alpha). For asphalt pavement, the BLAS thickness varied between 2.90 and 4.31 mm and that of BLBS varied between 28.00 and 45.38 cm. For sand pavement, the BLAS thickness varied between 2.55 and 3.29 mm and that of BLBS varied between 15.00 and 46.44 cm. The thickness varied with freezing and thawing processes. The boundary layer calculation method described in this paper can provide a relatively stable boundary for temperature field analysis.