紫花苜蓿根系-砂土复合体力学特性  

Mechanical properties of alfalfa root-soil composite

作　　者：王贵荣[1,2] 王凯 袁林[1,2] 吴延斌 WANG Guirong;WANG Kai;YUAN Lin;WU Yanbin(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China;Institute of Ecological Enviromental Restoration in Mine Areas of West China,Xi’an University of Science and Technology,Xi’an 710054,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]西安科技大学西部矿山生态环境修复研究院,陕西西安710054

出　　处：《西安科技大学学报》2023年第1期99-108,共10页Journal of Xi’an University of Science and Technology

基　　金：国家自然科学基金项目(42177155)。

摘　　要：为探究紫花苜蓿根系对砂性土的增强作用,以黄土为基础土料,河砂为改性土料,将改性土料加入基础土料中,制备含砂质量百分比为0%,20%,40%,60%的紫花苜蓿根系-砂土复合体;通过根系拉伸试验,得到根系抗拉强度;通过直剪试验,得到不同含砂量和根系面积比(根系横截面积AR与土体横截面积A的比值)的根土复合体抗剪强度参数;采用电子放大镜对紫花苜蓿根系、根土复合体及剪切后试样进行观察,分析根系与土体的结构和特征。结果表明:随着紫花苜蓿根径的增大,抗拉强度呈指数降低;随着含砂量的增加,根土复合体黏聚力呈现先增大后减小的趋势;随着根系面积比的增加,根土复合体黏聚力逐渐增大;以根系抗拉强度和根系面积比的乘积为自变量,实测的抗剪强度增量为因变量,进行线性拟合得到K值,在含砂量为0%,20%,40%,60%下的K值分别为0.38,0.56,0.2,0.09;当根土复合体受到剪切力时,根系所受到的拉应力可转变为增强剪切面的摩擦力和抵抗土体变形的剪应力,提高了根土复合体抗剪强度。研究结果对矿山生态修复中的土体重构工作提供理论依据。In order to explore the enhancing effect of alfalfa roots on sandy soil, the loess was taken as the basic soil material and river sand as the modified soil material, and the modified soil material was added into the basic soil material to prepare alfalfa root-soil composite with sand mass percentage of 0%,20%,40% and 60%.The root tensile strength was obtained by the root tensile test.Through direct shear test, the shear strength parameters of the root soil composite were obtained with different sand content and RAR(ratio of root cross-sectional area(AR)to soil cross-sectional area(A)).The electronic magnifying glass was used to observe alfalfa root, root soil composite and shear samples.The structure and characteristics of root and soil were analyzed.The results are as follows: with increase of root diameter, the tensile strength increased exponentially.With the increase of sand content, the cohesion of root soil composite increased first and then decreased.With the increase of RAR,the cohesion of the root soil composite gradually increased.When the product of root tensile strength and RAR as the independent variable and the measured shear strength increment as the dependent variable, a linear fitting was performed to obtain the K value, which was 0.38,0.56,0.2 and 0.09 respectively when sand content was 0%,20%,40% and 60%.When the root soil complex was subjected to shear force, the tensile stress of the root system could be transformed into friction force to enhance the shear plane and shear stress to resist soil deformation, thus promoting the shear strength of the root soil complex.The friction force and shear stress generated by the root system could improve the shear strength of the root soil composite.This research would support soil reconstruction in mine ecological restoration.

关 键 词：含砂量 根系面积比 根土复合体 抗剪强度 根系拉伸 

分 类 号：P642[天文地球—工程地质学]