灌木对黄土边坡的加固效应

Effect of shrub on stability of loess slope

植物对边坡稳定性的贡献源于根系对土体的加劲作用、根系吸水消耗孔隙水压力及其引起的抗剪强度增加.通过对非饱和含根土开展剪切试验建立了根-土复合体的抗剪强度模型,其抗剪强度是根系密度和土壤含水率的函数.通过建立二维根系吸水模型,开展根系吸水条件下的渠道边坡土壤水分运动数值模拟.根据土壤水分动态分布和根-土复合体抗剪强度模型计算了不同气象阶段植被渠道边坡的稳定性.对比相同时刻植被边坡和裸土边坡的稳定性计算结果发现,植物根系通过加劲土壤和吸取土壤水分能够显著增强黄土渠道边坡的稳定性.

Vegetation contributes to slope stability through reinforcement of the soil,dissipation of pore pressures caused by root water uptake,and increasing the shear strength by matric suction.In this investigation,laboratory shear tests of unsaturated loess samples with shrub roots were conducted;and a shear strength model of the root permeated soil was established via fitting the test data,which indicates the shear strength is the function of root density and soil water content.Furthermore,a two-dimensional model of root water uptake was developed;and the numerical modeling of shrub root water uptake from a canal slope was demonstrated.Based on the dynamical distribution of soil water in canal slope and the shear strength model of the root permeated soil,the stability factors of the vegetated canal slope in different hydrological stages were computed.Compared the stability factors of vegetated slope with that of bared slope at same moments,it can be seen that the vegetation obviously strengthens the canal slope by reinforcing the soil and uptaking the soil moisture.