植物根系固土作用对崩岗稳定性影响的数值模拟

Numerical Simulation on the Effect of Plant Root Systems on Soil Reinforcement on the Stability of Collapsing Gullies

植物护坡是防治崩岗侵蚀的重要方法,为了研究根系固土作用对鄂东南通城县崩岗崩壁稳定性的影响,将根系简化为主直根型,通过室内试验得到崩壁各土层的力学参数,应用Abaqus程序构建造林崩壁稳定性分析模型(将崩壁坡面以直线近似替代),分别计算了主根系长度、种植间距、根系布置位置、主根入土方位、侧根分支角度、根系相对加固位置的变化对崩壁稳定安全系数的影响。模拟结果表明:在控制崩壁植物根系单变量变化的条件下,主根长度越大,崩壁的安全系数越大;安全系数与种植间距之间呈双折线负相关关系;安全系数随着侧根分支角度的增加先增大后减小;安全系数随着根系距坡趾距离的增加先递增后回落直至趋于稳定;只在坡面偏下部的局部范围内种植主根垂直坡面生长的植物时安全系数存在最优值。

Collapsing erosion is a common and specific form of soil erosion in granite areas of southern China,while eco-protection slope through roots is a cost-effective and environmentally compatible method for prevention of collapsing erosion.In the aim of investigating the influence of root reinforcement systems on the stability of collapsing gullies wall,the slope reinforcement mechanism of the plant root was studied in this paper.The plant root was simplified into taproot type.A 2 Dfinite element model of collapsing gullies wall considering the roots was established by means of ABAQUS software platform.The effect of the variation of some factors such as length,spacing,position,entry direction,lateral branch angle and root-slope toe distance on the safety factor of collapsing slope was analyzed respectively.Considering the influence of a single factor,the following conclusions are drawn:with the increase of taproot length,the stability of collapsing slope can be improved.A double fold linear negative correlation appears between the safety factor of collapsing gullies wall and the planting spacing.The safety factor first increases with the lateral branch angle,reaching apeak value at a lateral branch angle of 45 degree,then turns gradually attenuated.With the increase of distance from the root to the slope toe,the safety factor first increases and then declines until levels off.The safety factor is the largest when the roots in the lower slope are perpendicular to the slope surface.