人工石质边坡构树根系抗剪特性研究

Study on Characteristics of Root Shear of Broussonetia papyrifera L. on Rocky-steep Slope

研究构树根系抗剪切特性,可为岩石边坡生态防护提供理论依据。采用室内单根抗剪切试验分析了上、下坡向,一级、二级、三级侧根的抗剪切强度和应力—应变曲线。结果表明:下坡向根系数量、根径大于上坡向,根系平均长度小于下坡向;根系的剪切力-应变曲线与其生长方位、根径、根系分级有相似的曲线形状;分级根系的剪切力为一级>二级,下坡向一级根系剪切力大于上坡向,但二级根系剪切力反而小,最大剪切力随根径增加而增大;根系的抗剪强度随着根径的增大而减小,呈线性关系;抗剪强度值随着根径的而增大;下坡向根系平均抗剪强度大于上坡向,各根系平均抗剪强度为一级>二级>三级,但上下坡向和各级根系间无显著差异。抗剪强度是影响边坡稳定的重要因素,它既可以加固土体,又能影响植物的锚固作用。

In order to investigate how Broussonetia papyrifera L. root shearing characteristics varied with root diameter, growth direction and lateral order, shearing forces of these samples were measured by an electronic universal testing machine. Relationships between growth direction, lateral order and shear characteristics were analyzed systematically. The results showed that both root amount and average diameter of downslope were larger than those of upslope, while the average length of upslope was larger than that of downslope. Force-displacement curves of roots with different orders, root diameters, growth directions had the similar shapes, shear force of the 1st order was larger than the 2nd-order＇s. Maximum shear force in- creased with increase of root diameter. Linear relationship between shear strength and diameter was observed, shear strengths decreased with increase of diameters. There were no significant differences of shear strength which were observed among the lst-order, 2nd order, 3rd-order laterals of downslope, although the rank was lst-order〉2nd-order〉3rd-order; and no significant differences of shear strength between upslope and downslope were observed. Shear strength is key factor affecting the stability of slope. In all, downslope roots with the 1st order and 2hal-order maintained the slope soil shearing properties.