Details

Autor(en) / Beteiligte

• QingBo Bai Xu Li YaHu Tian

Titel

A method used to determine the upper thermal boundary of subgrade based on boundary layer theory

Ist Teil von

• 寒旱区科学（英文版）, 2015-08, Vol.7 (4), p.384-391

Ort / Verlag

School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In the numerical simulation of long-term subgrade temperature fields, the daily variation of soil temperature at a certain depth h is negligible. Such phenomenon is called the ＂boundary layer theory.＂ Depth h is defined as the boundary layer thickness and the soil temperature at h is approximately equal to a temperature increment plus the average atmosphere temperature. In the past, the boundary layer thickness and temperature increment were usually extracted from monitored data in the field. In this paper, a method is proposed to determinate the boundary layer thickness and temperature incre- ment. Based on the typical designs of highway or railway, the theoretical solution of boundary layer thickness is inferred and listed. Further, the empirical equation and design chart for determining the temperature increment are given in which the following factors are addressed, including solar radiation, equivalent thermal diffusivity and convective heat-transfer coefficient. Using these equations or design charts, the boundary layer thickness and temperature increment can be easily determined and used in the simulation of long-term subgrade temperature fields. Finally, an example is conducted and used to verify the method. The result shows that the proposed method for determining the upper thermal boundary of subgrade is accurate and practical.