不同植被条件下斜坡土体大孔隙特征分析

Characteristics of macropores in soil of slope under different vegetation measures

采集高盖度玄武岩斜坡典型植被云南松和狗牙根土体，基于水分穿透法，采用方差分析、回归分析方法，进行对滑坡孕育及发生有显著影响的土体大孔隙特征研究。分析表明：植被类型并不能控制土体大孔隙水分运动的整体发展规律，但影响水分穿透曲线的振幅及稳定时间。2种植被土体均存在大直径（〉2．4mm）大孔隙量小，小直径大孔隙量大的特征；不同植被土体各层大孔隙数量不同，但并不影响大直径大孔隙数量的土体空间分布。2种植被土体大孔隙直径主要集中于2．6--0．6mm，平均直径范围为1．86～1．0mm；大孔隙尺寸范围受控于植被类型，而尺寸分布受其影响较小。不同植被土体水分流速受大孔隙特征的影响程度不同。总体上，2种植被土体各层大孔隙数量、平均孔径、最大孔径、最小孔径、大孔隙度、稳渗速率均随深度增大而减小；根系和有机质对不同植被土体大孔隙特征有不同的影响；颗粒分布对云南松和狗牙根土体各层大孔隙特征参量无显著功效。研究得出大孔隙的一个下限尺度值为600um。

We had collected the soils of high-cover basalt slope grown with Pinus yunnanensis and Cynodon dactylon, and investigated the properties of macropores which have a significant effect on the formation and occurrence of landslide based on the water breakthrough method and variance, regression analysis. It was demonstrated that the vegetation type can not control the general evolution law of the water movement in macropores, but it does influence the amplitude and stability time of the water breakthrough curve. The two soils showed the characteristic that large diameter（〉2.4 mm） macropores accounts less amount, and the small macropores accounts more. Different vegetation soils have the different macropore quantity in different depth, but it has no influence on the spatial distribution of large macropore quantity. The diameter of macropores in the two soils mainly concentrate in 2.6 - 0.6 mm, while the range of average diameter is 1.86 - 1.0mm. Macropore size range is much more controlled by the type of vegetation than its size distribution. The water flow rate in different vegetation soils are influenced in different level by the macropore character. On the whole, with the depth increases, the two soils＇ macropore quantity, average-maximum-minimum diameter, macroporosity and the stable infiltration coefficient will decrease. Roots and organic matter have different influence on macropore＇s properties in different vegetation soils. For soils grown with Pinus yunnanensis and Cynodon dactylon, particle distribution has no obvious contribution to the the macropore＇s properties in different depths. The results have shown that the macropore＇s lower limit scale value is 600 um.