It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mec...It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mechanical properties can be obtained through the pullout force and root slippage curve(F-S curve). About 120 Pinus tabulaeformis single roots whose diameters ranged from 1 mm to 10 mm divided into 6 groups based on different root embedment length(50 mm, 100 mm and 150 mm) and different load velocity(10 mm·min^(-1), 50 mm·min^(-1), 100 mm·min^(-1) and 300 mm·min^(-1)) were investigated using the pullout method. This study aims to explore the mechanical properties of the soil-root interface in the real conditions using the pullout test method. The results showed two kinds of pullout test failure modes during the experimental process: breakage failure and pullout failure. The results showed that the roots were easier to be broken when the root diameter was smaller or the loading speed was larger. The relationship between the maximum anchorage force and root diameter was linear and the linearly dependent coefficient(R^2) was larger than 0.85. The anchorage force increased with the root embedment length. An increase of 10%^(-1)5% for the maximumanchorage force was found when load speed increased from 10 to 300 mm.min^(-1). The mean peak slippage of the root was from 13.81 to 35.79 mm when the load velocity varied from 10 to 300 mm.min^(-1). The study will be helpful for the design of slopes reinforced by vegetation and in predicting risk of uprooting of trees, and will have practical benefits for understanding the mechanism of landslide.展开更多
Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soi...Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soil conductance, soil-root conductance and root conductance. The vaues and relative importance varywith soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulicconductance of roots in wet soils, the soil-root interfaCe becomes a major limiting factor to water uptake inmoderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance inseriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be usedto evaluate the drought-resistance and water use efficiency of crops.展开更多
The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax...The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax￣b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a andb are the regression constants). The depletion rate of phosphate in soil near the root surface was higher andthe depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content thedepletion range was wider, generally The application rate of phosphate led to the greater depletion intensityof phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, whichdecreased with increasing clay content or increa.sing buffering power of soil, decreased in the order as loessalsoil and black fou soil> lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in theform of KH_2PO_4. This result indicated that the phosphate distribution and its movement in the soil-rootinterface zone closely related with the buffering capacity of soil.展开更多
针对目前缺乏水稻钵苗多株根系交织于基质形成独立钵体复合体基础模型研究的问题,同时为后续开展水稻钵苗移栽机构栽植过程探究机械-钵体互作规律提供理论基础,本文依据水稻钵苗根系物理机械特性与生长规律,提出了一种基于Matlab根系数...针对目前缺乏水稻钵苗多株根系交织于基质形成独立钵体复合体基础模型研究的问题,同时为后续开展水稻钵苗移栽机构栽植过程探究机械-钵体互作规律提供理论基础,本文依据水稻钵苗根系物理机械特性与生长规律,提出了一种基于Matlab根系数值模拟生长的水稻钵苗钵体复合体离散元模型建立方法。通过破坏性检测对移栽期水稻钵苗根系的几何形态与根系拓扑关系及基质相关参数进行测量与分析,结合钵盘边界因素及根-根、根-钵盘间交互生长特性,建立水稻根系生长规律相关特性函数,并通过Matlab程序设计获取水稻钵苗根系生长拓扑轨迹。利用分割排序法求解完整粒子中心坐标,依托EDEM软件平台分别将所建立的水稻钵苗根-基质离散元几何模型与EdinBurgh Elasto-Plastic Adhesion with Bonding接触力学模型结合,实现水稻钵苗钵体复合体离散元模型的建立。开展水稻钵苗钵体压缩和剪切试验对比研究,结果表明,仿真结果与试验结果趋向保持一致,误差满足相关要求,验证了水稻钵苗钵体复合体离散元模型的可行性。展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.YX2010-20)the Open Projects Foundation of Key Laboratory of Soil and Water Conservation & Desertification Combat (Beijing ForestryUniversity), Ministry of Education of P.R. China (No.201002) the National Natural Science Foundation of China (No. 31570708, No.30901162)
文摘It is important to quantify the effect of the root diameter, the embedment length of the root and load speed on the soil-root interface mechanical properties for studying the root anchorage. The soilroot interface mechanical properties can be obtained through the pullout force and root slippage curve(F-S curve). About 120 Pinus tabulaeformis single roots whose diameters ranged from 1 mm to 10 mm divided into 6 groups based on different root embedment length(50 mm, 100 mm and 150 mm) and different load velocity(10 mm·min^(-1), 50 mm·min^(-1), 100 mm·min^(-1) and 300 mm·min^(-1)) were investigated using the pullout method. This study aims to explore the mechanical properties of the soil-root interface in the real conditions using the pullout test method. The results showed two kinds of pullout test failure modes during the experimental process: breakage failure and pullout failure. The results showed that the roots were easier to be broken when the root diameter was smaller or the loading speed was larger. The relationship between the maximum anchorage force and root diameter was linear and the linearly dependent coefficient(R^2) was larger than 0.85. The anchorage force increased with the root embedment length. An increase of 10%^(-1)5% for the maximumanchorage force was found when load speed increased from 10 to 300 mm.min^(-1). The mean peak slippage of the root was from 13.81 to 35.79 mm when the load velocity varied from 10 to 300 mm.min^(-1). The study will be helpful for the design of slopes reinforced by vegetation and in predicting risk of uprooting of trees, and will have practical benefits for understanding the mechanism of landslide.
文摘Water movement into and out of roots depends on the water potential difference between the bulk soiland the root xylem and the total hydraulic conductance of the pathway, which can be divided into three parts,i.e. soil conductance, soil-root conductance and root conductance. The vaues and relative importance varywith soil water content. The general rule is that water uptake by roots is mainly limited by radial hydraulicconductance of roots in wet soils, the soil-root interfaCe becomes a major limiting factor to water uptake inmoderately dry soils, and the water uptake is limited by the rapidly decreasing soil hydraulic conductance inseriously dry soils. Meanwhile these limiting factors vary with crop variety, and these variations can be usedto evaluate the drought-resistance and water use efficiency of crops.
文摘The phosphate in the soil-root interface zone under various soil water contents and application rates ofphosphate was still of depletion distribution which could be described by a power function in the form ofC/Co= ax￣b(C/Co is the relative content of fertilized phosphate in a distance from the root surface x, a andb are the regression constants). The depletion rate of phosphate in soil near the root surface was higher andthe depletion range was narrower under lower soil moisture. On the contrary, at higher soil water content thedepletion range was wider, generally The application rate of phosphate led to the greater depletion intensityof phosphorus was higher in the heavier texture soils. In general, the depletion intensity in the soils, whichdecreased with increasing clay content or increa.sing buffering power of soil, decreased in the order as loessalsoil and black fou soil> lou soil> yellow cinnamon soil when 50 or 100 mg of phosphorus were applied in theform of KH_2PO_4. This result indicated that the phosphate distribution and its movement in the soil-rootinterface zone closely related with the buffering capacity of soil.
文摘针对目前缺乏水稻钵苗多株根系交织于基质形成独立钵体复合体基础模型研究的问题,同时为后续开展水稻钵苗移栽机构栽植过程探究机械-钵体互作规律提供理论基础,本文依据水稻钵苗根系物理机械特性与生长规律,提出了一种基于Matlab根系数值模拟生长的水稻钵苗钵体复合体离散元模型建立方法。通过破坏性检测对移栽期水稻钵苗根系的几何形态与根系拓扑关系及基质相关参数进行测量与分析,结合钵盘边界因素及根-根、根-钵盘间交互生长特性,建立水稻根系生长规律相关特性函数,并通过Matlab程序设计获取水稻钵苗根系生长拓扑轨迹。利用分割排序法求解完整粒子中心坐标,依托EDEM软件平台分别将所建立的水稻钵苗根-基质离散元几何模型与EdinBurgh Elasto-Plastic Adhesion with Bonding接触力学模型结合,实现水稻钵苗钵体复合体离散元模型的建立。开展水稻钵苗钵体压缩和剪切试验对比研究,结果表明,仿真结果与试验结果趋向保持一致,误差满足相关要求,验证了水稻钵苗钵体复合体离散元模型的可行性。
