冻融条件下通辽粉砂导热系数的试验研究

Laboratory Investigation on Thermal Conductivity of Tongliao Silty Sand Under Freezing-Thawing Condition

土体导热系数是进行寒区工程热工计算的重要参数。主要受到含水率、冻融状态等因素的影响。准确测定不同含水率和冻融条件下土体的导热系数,探究其变化规律,对寒区工程热工计算和冻害防治具有重要意义.本文对采自内蒙古通辽某高速公路的路基填土(粉质砂土)在-12.5～12.5℃的温度和0%～14%的含水率条件下进行了导热系数试验.试验结果表明:通辽粉砂导热系数随含水率的增加表现出三个阶段和两次跃变;温度对导热系数的影响随含水率增加分为两个阶段.通过对比相同含水率下正、负温区的导热系数平均值与各温度下导热系数的实测值,确定了最接近导热系数平均值的实测温度,将其定义为该含水率下的最佳测试温度,在该温度下测试导热系数可减少试验次数。

The thermal conductivity of soil is an important parameter for thermal engineering calculation in cold regions, which is mainly affected by the water content, state of freeze-thaw, and the other factors. It has important significance for thermal calculation and frost damage prevention of engineering in cold regions by accurate determination of thermal conductivity of soil with different water content and freeze-thaw conditions. In this paper, the thermal conductivity of subgrade soil （silty sand） in a freeway of Inner Mongolia, Tongliao, at the temperature of -12.5 ~ 12.5℃ and the water content of 0%-14% was tested. The experimental results show that the thermal conductivity of Tongliao silt has three stages and two jumps with the increase of water content. The influence of temperature on thermal conductivity can be divided into two stages with the increase of water content. Through the comparison of average value of thermal conductivity in positive and negative region with actual thermal conductivity in different temperature, we can get the temperature which is close to the average value of thermal conductivity, which is defined as the best test tern- perature in this water content. It can reduce the test times of thermal conductivity at this temperature.