热变形对饱和黏性土渗透系数的影响

Influence of Thermal Deformation on Hydraulic Conductivity of Saturated Clayey Soil

为了探究5~30℃温度变化对黏性土渗透性影响机理,同时考虑温度变化诱导的流体性质和土体变形对渗透系数的影响,提高模型的应用范围和精度,本文先采用室内实验和理论模型相结合的方法对该问题进行了研究,然后基于变温渗流实验数据,构建了土体应变与介质孔隙比的关系式,最后对Kozeny-Carman模型的修正模型(REN模型)进行了进一步修正。结果表明:在地下水常见的5~30℃温度区间,温度变化引起土体变形对黏性土渗透系数的影响显著,仅考虑流体黏度随温度变化而忽略黏性土形变影响的渗透系数计算误差最大可达40%;修正后的模型与现有渗透系数模型相比具有更好的性能;通过修正后的渗透系数模型分析,发现温度在5~20℃区间时,渗透系数变化的主控因素是流体黏度,此温度区间介质形变对渗透系数影响较小,影响程度低于10%;当温度在20~30℃区间时,温度引起介质形变诱导的渗透系数变化贡献率增大,对渗透系数影响最大超过40%。

In order to explore the mechanism of the effect of temperature changes on the permeability of clayey soil at 5-30℃,while considering the fluid properties induced by temperature changes and the influence of soil deformation on the hydraulic conductivity,and improve the application range and accuracy of the model,in this paper combination of laboratory experiments and theoretical models were used to study.Then,based on the experimental data of variable temperature seepage,a relationship equation between soil strain and medium void ratio was constructed.Finally,further modifications were made to the modified model of the Kozeny Carman model(REN model).The results show that in the common temperature range of 5-30℃in groundwater,the deformation of soil caused by temperature changes has a significant impact on the hydraulic conductivity of clayey soil.The maximum calculation error of hydraulic conductivity can reach 40%under considering only the variation of fluid viscosity with temperature and ignoring the effect of clayey soil deformation.The modified model has better performance compared to existing hydraulic conductivity models.Through the analysis of the modified hydraulic conductivity model,it was found that the main controlling factor for the change in hydraulic conductivity is fluid viscosity when the temperature is in the range of 5-20℃,and has a small impact on the hydraulic conductivity with a degree of less than 10%.When the temperature is in the range of 20-30℃,the contribution rate of hydraulic conductivity induced by soil deoformation caused by temperature increase,and an maximum impact on the hydraulic conductivity exceeding 40%.