摘要
【目的】为提高植物根系固土效果模型量化的准确性,针对植物根系在土壤中受破坏的不同方式,基于植物生长过程的根土复合体直剪试验,利用根的拔出与抗拉试验,分析根系在不同生长时期的受力机制,定量评估植物根系对土壤的加固效果。【方法】在原有直剪仪器的基础上,设计了一套分离式、可测定盆栽植物根系固土效果的装置。将12棵3年生山矾幼树样本直接种植于直剪盒,针对移植后1个月、4个月和1年后山矾根系的单根抗拉强度、拔出强度和根土复合体的抗剪强度进行测定,建立植物单根直径与单根抗拉强度、拔出强度的关系曲线。在时间尺度上,研究影响其根系固土的相关参数变化,分析根系与土壤的相互作用机制和根系的破坏情况,并优化现有Wu模型,并尝试评估动态生长过程中的根系固土效果。【结果】1)植物根系固土效果受抗拉强度与拔出强度的共同影响,在植物的生长的过程中,拔出强度对固土效果的影响比抗拉强度更加显著;2)随着植物种植时间的增加,4个月后根土复合体的抗剪切强度显著增加,1年后根土复合体的抗剪切强度较前4个月增长放缓。根土复合体发生剪切破坏后,根系发生断裂破坏的概率随种植时间的增加而增加。3)将根系抗拉和拔出强度2个参数加入到植物根系固土模型的计算中,可以更好地反映植物根系固土效果,特别是对于植物移植生长过程,模型计算结果与实际值平均相差仅为8.13%。【结论】植物根系在1年的生长周期内,根系数量不会发生较大变化,根系抗拉强度由其材料属性决定,也不会发生较大变化。而根系与土壤间的键合则变得更加紧密,根系的拔出强度增加显著,更多的根系在土壤发生破坏时发生断裂,最终提高根系加固土壤的效果。
【Objective】The role of plant roots in maintaining slope stability and soil mass has been widely recognized.However,the interaction between soil and roots is complex,so that it is difficult to accurately quantify the effect of root reinforcement. In order to improve the accuracy of root reinforcement quantification,in terms of the different mode of destroying roots in soil,this paper analyzed the tensile and pull-out strength of roots under various growth periods using direct shear tests and root strength tests. 【Method】A breakaway type instrument was designed on the basis of traditional direct shear apparatus,which can test the in-situ shear strength of root soil composite of potting plants（ as shear box）. In this study,12 well-grown 3-years-old Symplocos saplings were planted in direct shear boxes. The tensile strength,pull-out strength of roots and shear strength of roots-soil composite were measured in one month,4 months and one year after the plants were transplanted. The relationship between single root diameter and single root tensile strength and pull-out strength was analyzed. On the time scale,the changes in the related parameters of the root system were investigated,the interaction mechanism of root and soil and the destruction of root system were analyzed,and the existing Wu model wasoptimized,and the effect of root soil consolidation in the dynamic growth process was evaluated. 【Result 】The results reveal that 1） The root tensile and pull-out strength collectively played an important role in root soil reinforcement. In the process of plant growth,the effect of pull-out strength on soil consolidation was more significant than that of tensile strength; 2） The shear strength of root-soil composite significantly increased after four months,however the increasing rate reduced after 1 year. The percentage of breaking roots,especially for fine roots,increased with the increase of planting time; 3） The root tensile and pull-out strength were added to the calculation of plant root soil consolidation model,the proposed model can estimate the reinforcement effects more accurately with a deviation merely 8. 13%.【Conclusion】After one year＇s growth,the quantity of plant roots did not change greatly,and the root tensile strength,which is determined by its material properties,did not change obviously. However,the bonding between soil and root increased significantly because a number of roots tend to break when the soil was sheared,leading to increased root reinforcement with the plant growth.
作者
朱锦奇
王云琦
王玉杰
马超
Zhu Jinqi1, Wang Yunqi1,2, Wang Yujie1,2, Ma Chao1,2(1. Jinyun Forest Ecosystem Research Station School of Soil and Water Conservation,Beijing Forestry University Beijing 100083 ;2 . Beijing Engineering Research Center 〇 o Soil and Water Cooservation, Beijing Forestrr Universitt Beijing 100083)
出处
《林业科学》
EI
CAS
CSCD
北大核心
2018年第4期49-57,共9页
Scientia Silvae Sinicae
基金
北京高等学校青年英才计划项目(YETP07510)
关键词
根系
破坏方式
抗拉强度
拔出强度
模型
roots
failure mode
tensile strength
pull-out strength
model
