摘要
为探究香根草根系对红黏土剪切特性的影响,选取一年生香根草根-红黏土复合体为研究对象,在获取红黏土和香根草根基本参数的基础上,通过直接剪切试验、单根拉拔试验、界面剪阻试验得到不同破坏模式下根土复合体抗剪强度及剪切特征参数,并进一步分析了根段倾角、土体干密度与含水率影响下的抗剪强度变化规律。研究结果表明:不同法向荷载下的根土复合体的直剪强度均大于素土,当生长方向与受剪方向夹角较小时,土体抗剪强度增幅较大,当根轴与剪切方向平行时,根固效应比二者正交时更好,根系的加入对黏聚力提升的效果显著;抗拔力随拉拔位移的增加而增长,并在3~8 mm位移时出现峰值,其后经历快速和缓慢降低2个阶段,直至根段被完全拔出;拉拔力、界面抗剪强度均与干密度呈正相关性,但当土体含水率约为20%,即最优含水率附近时出现峰值;随着土体干密度的增大,根表与土颗粒之间的黏结得到了增强,同时根土接触面积和摩擦效应也出现同步增长;根土界面抗剪强度、界面黏聚力、界面摩擦因数比均在含水率为20%左右达到最大值;在给定土体密实度水平下,通过调控根系生长环境湿度,可以改善根土摩擦效应和减少根系拉拔破坏。研究成果可为准确评价不同失效模式下根土复合体的抗剪强度提供试验依据,对于根系固土模型中剪切参数的合理选取具有一定参考价值。
To investigate the influence of vetiver roots on the shear properties of red clay,one-year-old vetiver root-red clay composites were selected as the research object.After obtaining the basic parameters of red clay and vetiver roots,the shear strength and shear characteristic parameters of the root-soil composite under different failure modes were obtained through direct shear tests,single root pullout tests,and interfacial shear resistance tests.Furthermore,the variation laws of shear strength under the influences of root segment inclination angle,soil dry density,and water content were analyzed.The results show that the direct shear strength of the root-soil composite under different normal loads is greater than that of plain soil.When the angle between the root growth direction and the shear direction is smaller,the increase in soil shear strength is larger.When the root axis is parallel to the shear direction,the root reinforcement effect is better than that under orthogonal conditions.The addition of roots shows a significant effect on the improvement of soil cohesion.The pullout force increases with increasing pullout displacement and reaches a peak at a displacement of 3-8 mm,after which two stages of rapid decrease and slow decrease are experienced until the root segment is completely pulled out.Both the pullout force and the interfacial shear strength exhibit positive correlations with soil dry density,but peak values appear when the soil water content is approximately 20%,that is,near the optimum water content.With increasing soil dry density,the bonding between the root surface and soil particles is enhanced,while the root-soil contact area and friction effect increase simultaneously.The interfacial shear strength,interfacial cohesion,and interfacial friction coefficient ratio of the root-soil interface all reach maximum values at a water content of approximately 20%.Under a given level of soil compaction,the root-soil friction effect can be improved and root pullout failure can be reduced by regulating the humidity of the root growth environment.The research results provide experimental evidence for the accurate evaluation of the shear strength of root-soil composites under different failure modes and have reference value for the reasonable selection of shear parameters in root-reinforced soil models.
作者
方薇
刘火
刘恬
王艺伟
FANG Wei;LIU Huo;LIU Tian;WANG Yi-wei(School of Transportation,Changsha University of Science&Technology,Changsha 410114,Hunan,China;Hunan Construction Engineering Group Co.,Ltd.,Changsha 410008,Hunan,China)
出处
《交通运输工程学报》
北大核心
2026年第2期210-224,共15页
Journal of Traffic and Transportation Engineering
基金
国家自然科学基金项目(52178413)
国家自然科学基金重点项目(52338009)
湖南省自然科学基金面上项目(2022JJ30593)
科技部重点研发计划(2021YFB2600900)。
