植物根系生长形态对膨胀土边坡土体抗剪强度的影响  

Influence of root growth configuration on shear strength of expansive soil slope

作　　者：李珍玉[1] 欧阳淼 肖宏彬[1] 林宇亮[2] 杨果林[2] LI Zhenyu;OUYANG Miao;XIAO Hongbin;LIN Yuliang;YANG Guolin(School of Civil Engineering,Central South University of Forestry and Technology,Changsha 410004,China;School of Civil Engineering,Central South University,Changsha 410075,China)

机构地区：[1]中南林业科技大学土木工程学院,湖南长沙410004 [2]中南大学土木工程学院,湖南长沙410075

出　　处：《中南大学学报（自然科学版）》2022年第1期181-189,共9页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51608545);国家重点研发计划项目(2019YFC1509800);湖南省林业科技创新计划项目(XLK202105-3)。

摘　　要：为了提高膨胀土边坡土体抗剪强度,增强植物根系在膨胀土边坡土体中的力学效应,提出用植物根系作为加筋材料防治膨胀土边坡的浅层失稳,调控植物根系在边坡土体中的生长分布方法。基于WU氏模型推导植物根系分布角度与膨胀土边坡土体抗剪强度增量的关系,构建1个膨胀土试验路堤边坡以模拟工程边坡实际情况,采用人工调控的方法调控香根草植物根系在膨胀土边坡土体中的分布,并与自然生长条件下根系相对比。研究结果表明:植物根系生长的角度对膨胀土边坡土体的抗剪强度影响较大,往膨胀土边坡上坡向生长的植物根系越多,其提高边坡土体抗剪强度的能力越强;通过人工调控作用,膨胀土边坡上坡向根系数量增加351.16%,且上坡向根系分布角由55°增大到75°;在自然生长条件下,65%左右的香根草根系偏向膨胀土边坡下坡向生长,上坡向生长的根系细短且稀疏,根径主要分布在0.8~2.0 mm之间;在人工调控条件下,香根草在膨胀土边坡的上坡向大量增生2级根和3级根,根系数量增幅为63.93%~361.76%;在自然生长条件下,单株香根草根系可使膨胀土边坡土体的抗剪强度提高5.28~8.62 kPa,而通过人工调控后香根草根系相较于自然生长条件下香根草根系,膨胀土边坡抗剪强度提高233.14%~294.08%。该研究结果可为膨胀土边坡生态防护工程提供参考。To improve the shear strength of expansive soil slope and enhance the mechanical effect of plant roots in the expansive slope soil,a method was proposed by using plant roots as reinforcement material and regulating the growth and distribution of them in the slope soil to prevent shallow instability of expansive soil slope.Based on Wu's model,the relationship between root distribution angles and increments of shear strength of expansive slope was derived.An embankment slope of expansive soil for test was built to simulate the actual situation of engineering slope.The distribution of vetiver root in expansive slope was controlled by artificial control method,which was compared with that under natural growth condition.The results show that the more the plant roots grow in the slope direction of uphill,the stronger the ability to improve the shear strength of slope soil.The number of root system increases by 351.16%and the distribution angles of roots increase from 55°to 75°through artificial regulation.Under the natural growth condition,about 65%of vetiver roots tend to grow in the downhill direction of expansive slope.The root system growing in the uphill direction is not only thin and short but also sparse.The root diameter is mainly between 0.8 mm and 2.0 mm.A large number of second-order roots and third-order roots are proliferated by the means of artificial regulation in the upslope of expansive soil slope.The percentage of root increment of single vetiver root system regulated is 63.93%−361.76%compared with that in nature.The shear strength of the expansive slope increases by 5.28−8.62 kPa by a single vetiver root system under the natural growth condition.However,the increment of shear strength of the expansive slope increases by 233.14%−294.08%compared with root system by manual control under natural growth condition.The research results can provide reference for the ecological protection engineering of expansive slope.

关 键 词：膨胀土边坡 香根草根系 人工调控方法 根系生长形态 抗剪强度 

分 类 号：TU44[建筑科学—岩土工程]