多年冻土区黑色沥青路面公路路基吸热特征

Heat Absorption Characteristics of Asphalt Pavement Highway Subgrade in Permafrost Region

为了研究冻土路基的吸热特征,对青藏高原多年冻土区的黑色沥青路面公路工程进行了现场试验监测。利用监测的地温数据,基于热传导理论计算分析了冻土路基的热量收支特征,并通过数值模拟研究了路基高度与宽度对热量收支的影响。研究结果表明:(1)路基的填筑会造成地基热量收支幅度减小,净吸热量较同深度的天然地层明显增大;(2)路基在当年10~12月以及翌年1~2月放热,在当年3~9月吸热,总体而言在一个完整的冻结融化周期内(一年)路基的累计吸热量大于累计放热量,净吸热量约为42.6 MJ/m^(2)·a,路基的净吸热量在冻土上限以上的地层及路基填土中耗散约50%,以下占50%;(3)在路基高度一定的情况下,随着路基宽度的增大,地基的净吸热量也逐渐增大,但增加的幅度逐渐减小;(4)在路基宽度一定的情况下,随着路基高度的增大,地基的净吸热量逐渐减小。

In order to study the heat absorption characteristics of permafrost subgrade,field tests monitoring section was conducted on the black asphalt pavement highway project in the permafrost region of the Qinghai-Tibet Plateau.Based on heat transfer theory,the heat budget characteristics of frozen soil embankment were calculated and analyzed using the monitored ground temperature data.Meanwhile,the influences of the height and width of the embankment on the heat budget were studied by numerical modeling.The results show that:(1)embankment construction can reduce the range of heat budget of foundation.The net heat absorption of embankment is significantly increased compared with the natural stratum at the same depth.(2)The subgrade emits heat in October to December and absorbs heat from March to September of the following year.In general,the accumulative heat absorption is greater than the accumulative heat release in a complete freezing-thawing cycle(one year).The net heat absorption is approximately 42.6 MJ/m^(2)·a.The net heat absorption of the subgrade is dissipated about 50%in the stratum above the permafrost upper limit and in the subgrade filling soil,and 50%below.(3)In the case of a certain subgrade height,the net heat absorption of the subgrade also gradually increases with the increase of subgrade width,but the increasing range gradually decreases.(4)When the width of subgrade is fixed,the net heat absorption decreases with the increase of subgrade height.