铜尾矿砂改良红黏土导热性能试验研究

回填土导热性能是直埋电缆载流量的重要影响因素之一。为探究各因素对改良红黏土导热性能的影响规律,制备不同掺砂率、干密度、含水率的试样,在恒温密闭的条件下,采用瞬态热线法测试试样导热系数,分析掺砂率、干密度、含水率对改良土导热系数影响规律。研究结果表明：铜尾矿砂对红黏土导热系数具有较好的改良作用,改良土的导热系数随着掺砂率、含水率均呈现线性增长。改良土导热系数随着干密度的增大,其增长趋势具有阶段性,当改良土的干密度大于1.65 g˙cm-3^时,导热系数的增长速率明显减小。铜尾矿砂对改良土导热系数的影响在于其中大量石英改善了固体骨架之间的传热效率。含水率和干密度对改良土导热系数的影响,主要在于其使改良土的三相传热方式发生了改变。基于测试结果,构建预测改良土导热的新模型,其能够较好预测改良土导热系数。

Experimental study on thermal conductivity of red clay improved by copper-tail ore

The thermal conductivity of backfill soil is one of the important factors affecting the load capacity of direct buried cable. In order to explore the influence law of various factors on the thermal conductivity of modified red clay, samples with different sand content, dry density and water content were prepared. Under the condition of constant temperature and airtight, the transient hot-wire method was used to test the thermal conductivity of samples, and the influence law of sand content, dry density and water content on the thermal conductivity of modified red clay was analyzed. The results show that the copper tail sand has a better effect on the thermal conductivity of red clay, and the thermal conductivity of the improved soil increases linearly with the sand content and water content. With the increase of dry density, the increase trend of thermal conductivity of improved soil is phased. When the dry density of improved soil is greater than 1.65g ˙cm-3, the growth rate of thermal conductivity decreases obviously. The effect of copper-tail sand on the thermal conductivity of modified soil is that a large amount of quartz improves the heat transfer efficiency between solid frames. The influence of moisture content and dry density on the thermal conductivity of improved soil is mainly due to the change of the three-phase heat transfer mode of improved soil. Based on the test results, a new model for predicting the thermal conductivity of the improved soil is established, which can better predict the thermal conductivity of the improved soil.