植被根系对土体渗透特性影响的试验研究

Experimental study on the influence of vegetation roots on soil permeability

植被根系可以调节土体中水分的入渗过程,植被土的渗透特性是决定植被护坡水力特性的重要参数,也是影响植被边坡稳定性的重要因素。文章选择高羊茅和小叶黄杨植被土,采用现场双环入渗试验分析入渗体积和渗透系数的变化,研究根系对入渗性能的影响;制备不同含根量的土样,通过室内变水头渗透试验研究重塑土和原状土的含根量对土体渗透特性的影响。结果表明:小叶黄杨植被土和含根量为0.82%的高羊茅植被土的入渗体积比裸土减少了50%,植被根系的存在对减少水的渗入量有着显著作用;无论是重塑土还是原状土,随着含根量的增加,根土复合体的饱和渗透系数逐渐减小,含根量越高的植被土对减少水分入渗有着更加显著的效果;含根量为0.30%~0.80%的重塑土的饱和渗透系数约为相近含根量原状土的3倍,现场双环入渗试验测得含根量为0.82%的高羊茅植被土的饱和渗透系数约为室内试验的5倍。上述研究可广泛用于生态护坡工程,根系对边坡的安全稳定起到良好的支撑作用。

Vegetation roots can regulate the process of water infiltration in the soil.The permeability of vegetation soil is an important parameter to determine the hydraulic characteristics of ecological slope protection and an important factor for engineers to calculate the stability of vegetation slope.In this paper,the vegetation soil of tall fescue and small-leaved boxwood was selected,and the changes of infiltration volume and permeability coefficient were analyzed by field double-ring infiltration test,so as to study the influence of roots on infiltration performance.Soil samples with different root contents were prepared,and the influence of root contents of remolded soil and undisturbed soil on soil permeability was studied by indoor variable head permeability test.The results show that the infiltration volume of the vegetation soil of small-leaved boxwood and that of the vegetation soil of tall fescue with root contents of 0.82%are 50%less than that of the bare soil.The existence of vegetation roots has a significant effect on reducing water infiltration.Whether it is remolded soil or undisturbed soil,the saturated permeability coefficient of the root soil complex decreases with the increase of root contents.The higher the root contents are,the more significant the effect is.The saturated permeability coefficient of remolded soil with 0.30%-0.80%root contents is about three times that of undisturbed soil with similar root contents,and the saturated permeability coefficient of the vegetation soil of tall fescue with 0.82%root contents is about five times that of undisturbed soil with the same root contents.The above studies can be widely used in ecological slope protection engineering.The roots play a good supporting role in the safety and stability of the slope.