植物根系吸水对边坡稳定性的影响

植物蒸腾作用导致根系吸水对边坡稳定性起着至关重要的作用。为了量化根系吸水的影响效果,采用有限元方法模拟了均布形、三角形、指数形、抛物线形4种植物根系的吸水作用,同时分析了根系形态、深度对于孔隙水压力分布的影响,并对边坡稳定性进行了定量计算。研究结果表明:随着根系吸水的不断进行,浅层孔隙水压力逐渐减小,基质吸力增大,非饱和土体剪切强度增加,边坡安全性逐渐提高;4种形态植物根系的孔隙水压力及安全系数比的包络线与根系分布形函数基本相同;指数形根系的地表孔隙水压力最小,安全系数比最大,对于边坡加固效果最明显;在根系总量一定时,植物根系深度越大,其影响范围(深度)相应增大,而对于地表根系土剪切强度增量的作用越小,相应边坡安全系数增量也越小。

Effects of Water Uptake by Plant Roots on Slope Stability

Due to transpiration, the uptake of water by plant root plays a vital role in the stability of soil slope. To quantify such effect, the water uptake by four types of plant roots(uniform, triangular, exponential, and parabolic) were simulated using finite element method,and the effects of root’s geometry and depth on pore water pressure were also analyzed. Results demonstrate that with the proceeding of water uptake, shallow pore water pressure gradually decreases, while safety factor climbs, the shear strength of unsaturated soil increases, and slope stability enhances. The envelopes of pore water pressure and safety factor ratio of the four types of plant roots are basically the same as the root distribution’s shape function. The exponential root has the most superior reinforcement effect on slope because of its lowest ground surface pore water pressure and largest safety factor ratio. Given the same total root amount, the greater the root depth is, the larger the influence zone is, and the lower vegetated soil’s shear strength and smaller factor of safety increment.