Influence of Thermal-protective Coating on the Culvert in Deep Seasonally Frozen Region and Its Optimized Design

In deep seasonally frozen region, the culvert changed the freezing process. The maximum depth of seasonal freezing in culvert foundation was about 2 times deeper than that in natural ground. In order to ease the situation, the measure of laying thermal-protective coating under the culvert is usually taken as a solution. In this paper, the advantages and disadvantages of three kinds of commonly used insulation materials were compared through the equivalent thickness conversion method. Based on the existing monitoring data of the culverts in Harbin to Dalian passenger dedicated line, a finite element model was established to simulate the temperature fields of the culverts with thermal-protective coating. To verify the effect of the thermal-protective coating, a numerical calculation was conducted respectively on different locations, modes and thickness of the thermal-protective coating to understand the influence of different conditions on the maximum frozen depth and to obtain the optimal laying scheme for culvert foundation. The results indicated that foam concrete is the ideal material for the thermal-protective coating, and the 38-cm-thick foam concrete should be laid on the top of the experimental culvert foundation as thermal-protective coating, which should be 10cm broader than the foundation. In this way, the maximum freezing depth under the culvert could be reduced, to meet the needs of construction in the cold region. © 2015, Science Press. All right reserved.