摘要
[目的]柠条锦鸡儿(Caragana korshinskii Kom.)是青藏高原东北部和黄土高原地区最为广泛的护坡和水土保持灌木之一,开展该种植物单根抗拉力学特性试验研究,为定量评价该种植物固土护坡效果提供理论依据。[方法]以根径为2.33~9.16 mm的中龄期柠条锦鸡儿根系为研究对象,通过单根拉伸试验对比分析了不同断裂模式和不同根径级别条件下,柠条锦鸡儿单根抗拉力学特性的差异性及其与根径之间的关系,并进一步探讨了单根断裂破坏模式及其应力—应变特征。[结果]柠条锦鸡儿单根存在周皮断裂和整体断裂2种断裂模式,2种断裂模式单根抗拉力和单根抗拉强度分别在(2,4],(4,6]和(6,8]mm以及(6,8]mm根径级别条件下存在显著性差异;相同断裂模式不同根径级别之间,4个单根抗拉力学特性指标差异程度各不相同。周皮断裂和整体断裂模式条件下,单根抗拉力随着根径的增大分别呈指数函数和幂函数增长趋势;单根抗拉强度、弹性模量和极限延伸率随着根径增大而降低。2种断裂模式的产生取决于单根受拉伸作用时,周皮、中柱鞘薄壁组织和次生维管组织的应力状态;对应的单根应力—应变曲线表现为弹性变形、弹塑性变形、应变硬化及周皮(断裂)破坏4个阶段。[结论]在采用单根拉伸试验来获取木本植物根系单根抗拉力学特性指标时,有必要考虑根径和断裂模式对单根抗拉力学特性的影响。
[Objective]Caragana korshinskii Kom.is one of the most widely used shrubs for slope protection and soil and water conservation in the northeastern Qinghai-Tibet Plateau and the Loess Plateau.The experimental study on the tensile mechanical properties of a single root of C.korshinskii was carried out to provide a theoretical basis for quantitative evaluation of soil fixation and slope protection of this plant.[Methods]Single root of C.korshinskii with root diameters of 2.33~9.16 mm at middle age was taken as the research object.The differences of tensile resistance characteristics of single root of C.korshinskii under different failure modes and different root diameter grades and their relationship with root diameter were compared and analyzed via single root tensile test,and the failure mode of single root and its stress-strain characteristics were further discussed.[Results]Two modes of failure of a single root,the periderm preferential breakage mode and the synchronous breakage mode,occurred when the roots were subjected to single root tensile test.The single root tensile force and single root tensile strength of the two failure modes were significantly different under the conditions of(2,4],(4,6],(6,8]mm and(6,8]mm root diameter grades,respectively(p<0.05).The difference degree of four single root tensile resistance characteristics indexes was different between different root diameter grades with the same failure mode.Under the periderm preferential breakage mode and the synchronous breakage mode,the single root tensile force of C.korshinskii increased with the increase of root diameter,there existed exponential and power relationship between single root tensile force and root diameter,respectively.In addition,the single root tensile strength,single root elastic modulus and single root limit extensile rate of C.korshinskii decreased with the increase of root diameter.The occurrence of these two failure modes of roots depends on the stress state of the periderm,thin wall tissue of middle column sheath,and the secondary vascular tissue when a single root is under tension.The stress-strain curves for the two failure modes can be divided into four stages:elastic deformation,elastic-plastic deformation,strain hardening and fracture failure.[Conclusion]It is necessary to consider the influence of root diameter and failure mode on single root tensile properties when single root tensile test is used to obtain single root tensile properties indexes of woody plant species.
作者
石川
梁燊
刘亚斌
朱海丽
李国荣
胡夏嵩
缪晓星
王延秀
SHI Chuan;LIANG Shen;LIU Yabin;ZHU Haili;LI Guorong;HU Xiasong;MIAO Xiaoxing;WANG Yanxiu(Department of Geological Engineering,Qinghai University,Xining 810016,China;Key Laboratory of Cenozoic Resources and Environment on the Northern Edge of the Qinghai-Tibet Plateau,Xining 810016,China;Qinghai Soil and Water Conservation Research Center,Xining 810001,China)
出处
《水土保持研究》
CSCD
北大核心
2023年第5期184-192,共9页
Research of Soil and Water Conservation
基金
国家自然科学基金资助项目(42002283,42062019)
第二次青藏高原综合科学考察研究项目(2019QZKK0905)。
关键词
青藏高原东北部
柠条锦鸡儿
单根拉伸试验
力学特性
断裂模式
应力—应变特征
northeastern Qinghai-Tibet Plateau
Caragana korshinkii Kom.
tensile test of single root
mechanical properties
failure mode
stress-strain characteristics
