【作者】 那顺；

【导师】 刘静； 张欣；

【作者基本信息】 内蒙古农业大学 ， 林业硕士（专业学位）， 2021， 硕士

【摘要】 根-土界面摩阻特性是反映根系固土能力的重要指标之一,为探究不同根系形态以及其他影响因素对根-土界面摩阻特性的影响,本文选取北沙柳(Salix psammophila)、小叶锦鸡儿(Caragana microphylla)、中国沙棘(Hippophae rhamnoides)、黑沙蒿(Artemisia ordosica)与其生长地土壤含细粒土砂为研究对象,使用TY8000伺服控制拉力试验机采用轴向拉拔的试验方法,研究了根径、土壤含水率、加载速率、树种对直根段摩阻特性以及摩擦系数的影响,以及不同影响因素分别对含侧根分支处根段中对两种不同根系形态(鲱骨型与二分枝型)摩阻特性的影响。研究结果如下:三种根系形态在拉拔过程中根-土界面摩阻力-滑移关系曲线变化规律基本相似,表现为快速增加,急剧降低以及较平缓三个阶段,但由于二分枝型根段在拉拔过程中为根土共同破坏,其摩阻力平缓阶段占比较少。二分枝型根段在拉拔过程中会出现单根断裂或分支点处劈裂两种破坏模式,试验中共有出现13组试验根破坏,占比6.5%。4种植物单根根-土界面摩阻力与根径呈线性正相关,摩阻强度与根径呈幂函数正相关,但黑沙蒿摩阻强度与根径呈幂函数负相关,4种植物中,中国沙棘、北沙柳、小叶锦鸡儿的摩擦系数随根径增加呈幂函数正相关,黑沙蒿呈线性负相关,4种植物二分枝型根段根-土界面摩阻力与两侧根根径呈线性正相关;土壤含水率对根-土界面摩阻特性影响显著,在5个土壤含水率梯度下,当土壤含水率由2.05%升高至10.05%时,4种植物根-土界面摩阻力、摩擦系数呈先增加后减小的变化趋势,均在含水率8.05%左右达到峰值,而4种植物中除北沙柳外滑移值峰值均表现为随含水率增大而增大的趋势;随加载速率的变化,根-土界面摩阻力、摩擦系数均表现为200mm/min>10mm/min>500mm/min。通过比较分析相同条件下4种不同植物的摩阻特性以及摩擦系数得出,4种植物中北沙柳固土效果较差,其它3种植物固土能力相近。含侧根分支处根段中,鲱骨型根段中须根的存在对根-土界面摩阻特性有显著提升,而两分支根间夹角是影响二分枝型根段根-土界面摩阻特性的重要因素。更多还原

【Abstract】 The root-soil interface friction characteristic is one of the important indexes reflecting the root system’s soil-fixing ability.In order to explore the influence of different root morphologies and other influencing factors on the root-soil interface friction characteristics,this thesis selects Salix psammophila,Caragana microphylla Hippophae rhamnoides,Artemisia ordosica and their growing soil containing fine-grained soil and sand are the research objects.The TY8000 servo-controlled tensile testing machine adopts the axial pull test method to study the root diameter,soil moisture content,loading speed,and tree species versus taproot.The influence of friction characteristics and coefficient of friction,as well as the influence of different influencing factors on the friction characteristics of two different root morphologies(herring-bone type and two-branch type)in the root segment of the branch containing lateral roots.The results of the study are as follows:During the drawing process of the three root systems,the root-soil interface friction resistance-slip relationship curve changes basically the same,showing three stages of rapid increase,sharp decrease and relatively gentleness.However,because the two-branched root section is in the process of drawing It is the joint destruction of the root and soil,and its frictional resistance is relatively small in the flat stage.The two-branched root segment will have two failure modes,single root fracture or splitting at the branch point during the drawing process.There are 13 groups of test root failures in the test,accounting for 6.5%.The root-soil interface friction of the four plants is linearly positively correlated with root diameter,and the friction strength is positively correlated with root diameter by a power function,but affected by chemical composition,the friction strength of Artemisia ordosica is negatively power function with root diameter.Correlation,the friction coefficients of the four species of Hippophae rhamnoides,Salix psammophila,and Caragana microphylla showed a positive power function correlation with the increase of root diameter,while Artemisia ordosica sphaerocephala showed a linear negative correlation.The root diameter of the roots on both sides is linearly positive;the soil moisture content has a significant impact on the friction characteristics of the root-soil interface.Under five soil moisture content gradients,when the soil moisture content increases from 2.05% to 10.05%,the roots of the four plants-Soil interface friction resistance and friction coefficient showed a trend of first increasing and then decreasing,reaching a peak at about 8.05% moisture content,and the peak slip values of the 4 plants except for Salix psammophila all showed an increase with moisture content And the increasing trend;with the change of loading rate,the root-soil interface friction and friction coefficient are both200mm/min>10mm/min>500mm/min.Through comparative analysis of the friction characteristics and friction coefficients of four different plants under the same conditions,it is concluded that among the four plants,Salix psammophila has a poor soil-fixation effect,while the other three plants have similar soil-fixation ability.In the root segment containing lateral root branches,the presence of fibrous roots in herring bone type root segment significantly improved the root-soil interface friction characteristics,and the Angle between two branched roots was an important factor affecting the root-soil interface friction characteristics of the two-branched root segment.更多还原