5种植物根系力学特性及其对土壤水分的响应

发布时间：2018-02-08 19:08

本文关键词： 单根抗拉特性抗弯特性根土复合体抗剪特性根土界面摩阻特性土壤含水率　出处：《内蒙古农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文以柠条(Caragana Korshinkii.Kom.)、沙棘(Hippophae rhamnoides.Linn.)、羊柴(Hedysarum frutycosum.Turcz.)、紫花苜蓿(Meddicagosativa.L.)、沙打旺(Astragaalus adsurgens.Pall.)的根系为对象,通过室内单根轴向拉伸、悬臂梁弯曲试验、根土复合体抗剪试验以及根土界面摩阻试验,研究了五种植物根系力学特性及对土壤水分的响应,得出以下结果:(1)3种植物根系直径在0～6mm范围时,单根极限抗拉力和抗弯力随着直径的增加均以幂函数递增,极限抗拉强度和抗弯强度随直径的增大均以幂函数递减。当直径在3种植物代表根径级时,单根极限抗拉力大小顺序为:沙棘(61.09N)柠条(56.91N)紫花苜蓿(26.42N),单根极限抗拉强度大小顺序为:柠条(126.12MPa)沙棘(79.17MPa)紫花苜蓿(68.5lMPa);3种植物单根抗弯力大小顺序为:柠条(0.55N)紫花苜蓿(0.38N)沙棘(0.16N);三种植物单根抗弯强度大小顺序为:柠条(22.09MPa)紫花苜蓿(17.36MPa)沙棘(4.77MPa)。当土壤含水率在4.5%～24.5%之间时,随着土壤含水率的增加,极限抗拉强度和抗弯强度呈减小的趋势。(2)5种植物根土复合体及素土剪切关系均服从莫尔-库仑理论。在自然生境下5种植物根土复合体抗剪强度和粘聚力值分别均大于素土。5种植物根土复合体抗剪强度间相比较,沙打旺的值(20.84KPa)大于柠条(17.41KPa)、沙棘(17.60KPa)、紫花苜蓿(14.56KPa)和羊柴(16.23KPa)的值。5种植物根土复合体粘聚力间相比较,沙打旺的值(12.22kPa)大于柠条(11.63kPa)、羊柴(11.56kPa)、紫花苜蓿(11.05kPa)、沙棘(10.65kPa)的值。5种植物根土复合体以及与素土内摩擦角间均无显著性差异。在土壤含水率4.5%—24.5%之间时,随着土壤含水率的增加,5种植物根-土复合体抗剪强度及粘聚力均呈现先增大后减少的趋势,土壤含水率的增加对根-土复合体及素土内摩擦角均无影响。(3)在自然生境下,摩擦系数大小顺序为沙棘根-土界面(0.7707)羊柴(0.7629)沙打旺(0.7159)和柠条(0.7157)紫花苜蓿(0.6239)土-土界面0.5337。5种植物根-土界面摩擦系数比大小顺序为沙棘根-土界面(1.44)羊柴(1.43)沙打旺(1.34)和柠条(1.34)紫花苜蓿(1.17),且5种植物摩擦系数比均大于1。在土壤含水率4.5%—24.5%之间时,随着土壤含水率的增加5种植物根-土界面及土-土界面的内摩擦角总体呈减小趋势,5种植物根土界面摩擦系数呈下降趋势,而土-土界面摩擦系数呈现出先增大后减小的趋势。(4)当根径在Omm～6mm范围内,5种植物根-土界面抗阻拉力均值随着根径的增大而呈线性增大;根-土界面的拉拔抗剪强度均值则随着根径的增大呈幂函数减小。在代表根径级下,5种植物单根平均拉拔抗剪强度大小顺序为:沙棘(112.11KPa)紫花苜蓿(97.65KPa)沙打旺(95.50KPa)柠条(89.81KPa)羊柴(69.38KPa)。在土壤含水率4.5%—24.5%之间时,随着土壤含水率的增加,5种植物根-土界拉拔抗剪强度均呈现出先增大后减小的趋势。根-土界面的拉拔剪切强度均在含水率为10.86%时出现峰值。
[Abstract]:In this paper, the roots of Caragana Korshinkii.Kom., Hippophae rhamnoides.Linn.Pall., Hedysarum frutycosum.Turcz.Pall., Meddicagosativa.L., Astragaalus adsurgens.Pall.are studied. The mechanical properties of five plant roots and their responses to soil moisture were studied. The following results were obtained: when the root diameter of three species of plants was in the range of 0 ~ 6 mm, the ultimate tensile and bending resistance of one root increased with the increase of diameter by power function. The ultimate tensile strength and bending strength decrease with the increase of diameter by power function. The order of ultimate tensile strength of single root is: Hippophae rhamnoides 61.09N) Caragana korshinskii 56.91N) alfalfa 26.42N, single root extreme tensile strength 126.12MPa) seabuckthorn 79.17MPa) the order of bending resistance of three species of alfalfa is: Caragana korshinskii 0.55N. The order of bending strength of three plants is: Caragana korshinskii 22.09 MPA) Alfalfa 17.36 MPA) seabuckthorn 4.77 MPa. When the soil moisture content is between 4.5% and 24.5%, the order of bending strength of three plants is: Caragana korshinskii 22.09 MPa. With the increase of soil moisture content, The ultimate tensile strength and bending strength of five plant root-soil complexes and their shear relationships are all based on the Mohr-Coulomb theory. The shear strength and cohesion of five plant root-soil complexes in natural habitats are determined by Mohr Coulomb theory. The shear strength of 5 plant root-soil complex was higher than that of plain soil. Compared with the values of 17.41 KPaA, 17.60 KPaA, 14.56 KPaA of Alfalfa and 16.23 KPA of Sheep, the cohesion of 5 plant root-soil complexes was higher than that of Caragana Caragana 17.41 KPA, Hippophae rhamnoides 17.60 KPA, Alfalfa 14.56 KPaand 16.23 KPA). The value of Astragalus dadanensis was 12.22 KPA, which was higher than that of Caragana Caragana 11.63 KPA, Astragalus alfalfa 11.05 KPA, Hippophae rhamnoides 10.65 KPA). There was no significant difference between 5 plant root soil complexes and frictional angles with vegetative soil. When soil moisture content was between 4.5% and 24.5%, there was no significant difference in soil moisture content between 4.5kPaand 24.5KPA and 10.65kPa. With the increase of soil moisture content, the shear strength and cohesion of five plant root-soil complexes increased first and then decreased, and the increase of soil moisture content had no effect on the friction angle of root-soil complex and plain soil. The order of friction coefficient is: Hippophae rhamnoides Root-soil interface 0.7707) Yangchaiao 0.7629) Astragalus korshinensis 0.7159) and Caragana korshinskii 0.7157)) Soil-soil interface 0.5337.5 plant root-soil interface friction coefficient ratio order is Hippophae rhamnoides Root-soil interface 1.44) Sand 1.43). The ratio of friction coefficient of 5 plants was all greater than 1. 5% when soil moisture content was between 4.5% and 24. 5%, and the ratio of soil friction coefficient was higher than 1% when soil moisture content was between 4. 5% and 24. 5%. With the increase of soil moisture content, the internal friction angle of 5 plant root-soil interfaces and soil-soil interfaces decreased in general, and the friction coefficient of 5 plant root-soil interfaces decreased. However, the friction coefficient of soil-soil interface increased firstly and then decreased.) when the root diameter was in the range of Omm~6mm, the mean value of the resistance to tensile force of five plant root-soil interfaces increased linearly with the increase of root diameter. The average tensile shear strength of the root soil interface decreases with the increase of root diameter. The order of the average tensile shear strength of 5 plants at the representative root diameter level is as follows: Hippophae rhamnoides 112.11KPa. alfalfa 97.65kPa. Caragana korshinskii 95.50KPa. When the soil moisture content ranged from 4.5% to 24.5%, With the increase of soil moisture content, the pull-out shear strength of five plants showed a tendency of first increasing and then decreasing, and the tensile shear strength of the root-soil interface showed a peak value when the moisture content was 10.86%.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q948

【参考文献】