基于根系构型的调控提高植物边坡根系固土能力  

Improvement of slope soil consolidation capacity of plant root system based on regulation of root architecture

作　　者：李珍玉[1] 欧阳淼 肖宏彬[1] 王聚山 李涛 刘思思[1] LI Zhen-yu;OUYANG Miao;XIAO Hong-bin;WANG Ju-shan;LI Tao;LIU Si-si(School of Civil Engineering,Central South University of Forestry and Technology,Changsha,Hunan 410004,China;East Ring Line Construction Headquarters of Chongqing Railway Hub of China Railway Chengdu Bureau Group Co.,Ltd.,Chongqing 400023,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]中国铁路成都局集团有限公司重庆铁路枢纽东环线建设指挥部,重庆400023

出　　处：《岩土力学》2021年第12期3271-3280,3290,共11页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51608545)。

摘　　要：植物护坡效果与根系在土壤中的空间造型和分布(根系构型)密切相关。采用水肥组合方法调控植物根系构型,通过一系列的室内外试验和理论分析,研究调控后的植物根系构型对边坡土体强度的影响。根据公路边坡工程的实际情况,制作了一路堤试验边坡,选用香根草植物作为生态边坡防护物种,采用9组不同的水肥组合调控植物根系在边坡土体内的生长构型。10个月后,通过十字架分层开挖,统计边坡植物根系发现,香根草根系含量随土层深度先增加后减少,与土层深度之间符合Gauss曲线关系。在施以水肥组合调控区域,香根草根系增生了大量的2级根和3级根,使得土体根系含量和根系表面积密度得到提高,且上坡向的根系占比超过下坡向,达到60%~66%。取不同区域原状土进行剪切试验发现,土体根系含量和根系表面积密度是影响土体抗剪强度的重要因素。通过回归分析发现,土体黏聚力与根系表面积密度之间符合线性关系。基于Wu氏模型,计算了植物根系对土体抗剪强度的增强作用,结果表明:自然生长条件下,单株香根草根系对边坡土体抗剪强度的增量ΔS大致为5.28~8.62 kPa;调控后,边坡土体增生的大部分2级和3级香根草根系与竖直方向的夹角大于坡角,使得单株香根草边坡土体的抗剪强度提高了17.59~33.97k Pa。上述研究结果表明,可利用水肥组合调控植物根系在边坡土体内的生长构型,进一步加固边坡土体,为提高植物边坡土体强度和预防边坡水土流失提供理论和实践依据。The effect of plant slope protection is strongly associated with the root architecture in soil.In this paper,the water-fertilizer combination method was used to regulate the plant root configuration,and the influence of the regulated plant root architecture on the slope soil strength was studied.In terms of the practice of highway slope engineering,a field fill slope for test was made.Vetiver was selected as slope protection species,and 9 groups of water-fertilizer combinations were designed to regulate the root architecture of plant in slope soil.After 10-months growth,the roots of plants on the slope were counted by cross layered excavation.It was found that the root content increased first and then decreased with the depth of soil layer,which accorded with Gauss curve.In control area with water-fertilizer combination,vetiver proliferated a large number of secondary and tertiary roots,which increased root content and root surface area density.The proportion of roots in the upslope direction was higher than that in the downslope direction,reaching 60%-66%.The shear test of undisturbed soil in different regions shows that the root content and root surface area density are important factors affecting the shear strength of soil.Regression analysis shows that there is a linear relationship between soil cohesion and root surface area density.The calculation based on Wu’s model shows that under natural growth conditions,the increment of shear strength of vetiver to slope soil is 5.28 kPa to 8.62 kPa,while under conditions of water-fertilizer combination,the angles between most of secondary and tertiary vetiver roots and the vertical are greater than the slope angle,which makes the shear strength of vetiver on slope soil increase by 17.59 kPa to 33.97 kPa.This research shows that water-fertilizer combination method can be used to regulate the root architecture of plants to strengthen slope soil,which provides theoretical and practical basis for improving slope soil strength and preventing slope soil erosion.

关 键 词：边坡工程 根系构型 调控 固土 抗剪强度 

分 类 号：TU413[建筑科学—岩土工程]