乔木根径、含量和分布类型对根土复合体饱和渗透系数的影响

Influence of tree root diameter,content and distribution type on saturation permeability coefficient of rooted soil

植物根系对土体的水力特性具有重要影响,但关于乔木根系对土体饱和渗透系数的定量研究缺乏。利用自制渗透实验箱,采用定水头实验方法,针对重塑根土复合体开展不同根径(1 mm≤d≤3mm、3 mm<d≤5 mm和5 mm<d≤8 mm)及含量(根体积含量0.4%~2.4%)和根的分布类型(水平和竖直)对其饱和渗透系数影响的定量研究。结果表明,相同根径条件下,根土复合体的饱和渗透系数与根体积含量呈线性正相关关系,但随着根径的增加,该线性关系斜率不断降低;根土复合体饱和渗透系数与根表面积含量也存在显著的线性正相关关系,方差分析表明,该线性关系不受根径的影响;确定了根的不同分布类型(水平和竖直)下根表面积含量与其饱和渗透系数之间的线性关系;此外,研究发现,根竖直向分布时的根土复合体饱和渗透系数随根表面积含量的变化率是水平分布的1.8倍左右。研究结果表明,根的存在可以显著提高土体的饱和渗透系数,且根土的表面接触是影响其水力特性的根本原因。

Root content has significant influence on the saturation permeability coefficient of soil,but there is a lack of quantitative research on the effect of coarse tree roots on soil saturation permeability coefficient.In this study,a self-developed infiltration experimental box with constant head method was used to conduct quantitative research on the influence of different root diameters(1 mm≤d≤3 mm、3 mm<d≤5 mm,and 5 mm<d≤8 mm)root content(root volume content:0.4%-2.4%),and root distribution forms(horizontal and vertical)on the saturation permeability coefficient of remold root-soil.The results indicate that,under the same root diameter conditions,the saturated permeability of the rooted soil is linearly and positively correlated with the root volume content.However,as the root diameter increases,the slope of this linear relationship continuously decreases.There is also a significant correlation between the saturated permeability coefficient and the root surface area content,and the variance analysis shows that the relationship is not affected by root diameter.Meanwhile,the linear relationship between the root surface area content and its saturation permeability coefficient was determined under different distribution types of roots(horizontal and vertical).In addition,it was found that the change rate of the saturation permeability coefficient of the rooted soil with the root surface area content in the vertical distribution was about 1.8 times that of the horizontal distribution.Based on the results above,it can be seen that the presence of roots can significantly improve the saturation permeability coefficient of soil,and the surface contact of root soil is the fundamental reason affecting its hydraulic characteristics.