含水率对非饱砂土热传导系数的影响

The Influence of Moisture Content to Thermal Conductivity of Unsaturated Sand

目的阐述含水率对非饱和砂土热传导系数的影响,为模型的参数选择提供科学依据.方法选用分选良好的粗砂、中砂和细砂以及毛乌素沙地的风积沙作为实验介质,利用JW-Ⅲ型热流计测定不同含水率条件下砂土的热传导系数,绘制热传导系数和含水率的关系曲线,运用非线性最小二乘法对实测数据与常用的热传导系数模型Campbell及Chung and Horton模型进行拟合.结果含水率在0～5%内热导率急剧增长,当含水率>10%时热导率的增长缓慢并趋于稳定.两模型基本能反映各试验介质的热传导系数和含水率的变化规律,对于扰动样该模型在含水率较小时不能很好地表征其变化规律.结论随着含水率的增加热导率值增加速率不同.在利用预测模型和经验公式时,应利用实测数据对其进行校正,减小误差.

This paper is to study the moisture content′s influence on thermal conductivity of unsaturated sand and provide the scientific basis for the parameters of the model.The methods are：choose the well sorted coarse sand,medium sand,fine sand and wind deposited sand in Maowusu sandy land as medium;measure thermal conductivity under different moisture content with JW-style heat-flow meter;draw out the moisture content and thermal conductivity relation curve;then fit the observed data by nonlinear least squares and Campbell,Chung and Horton thermal conductivity model.And the results are：when moisture content is between 0%~5%,the thermal conductivity rise rapidly;over 10%,the thermal conductivity rise slowly,and then reach at a stability state.The two models can reflect the changing regularity between moisture content and thermal conductivity,but for the disturbed sand they can not reflect it well.Adding moisture content,the thermal conductivity has different increasing speed.So in the use of forecasting models and experience formulas we should modify the observed data in order to reduce error.