Root tensile strength is an important factor controlling the performance of bio-slope stabilization works. Due to evapotranspiration and climate factors, the root moisture content and its suction can vary seasonally i...Root tensile strength is an important factor controlling the performance of bio-slope stabilization works. Due to evapotranspiration and climate factors, the root moisture content and its suction can vary seasonally in practice and may not equal soil suction. The influences of suction and root moisture contents were investigated on Chrysopogon zizanioides(vetiver grass) root tensile strength. The root specimens were equilibrated with moist air in different suction conditions(0, 10, 20, and 50 kPa), prior to root tension tests. The root-water characteristic curve or relationship between root moisture and suction, was determined. The increase in suction resulted in decreased tensile strengths of the grass roots, particularly those with diameter of about 0.2 mm, which constituted 50.7% of all roots. For 1 mm roots, the tensile strength appeared to be unaffected by suction increase. The average root tensile strengths were used to estimate the root cohesion in slope stability analysis to find variation of safety factors of a bioengineered slope in different suction conditions. The analysis showed that the critical condition of slope with the lowest factor of safety would happen when the soil suction was zero and the root suction was high. Such condition may occur during a heavy rain period after a prolonged drought.展开更多
为分析黄河源区高寒草甸植物单根的抗拉力学性质及其护岸的微观力学机理,以华扁穗草、线叶嵩草和金露梅3种优势滨河植物为研究对象,通过开展单根拉伸试验和石蜡切片试验,定量分析3种植物单根力学特性及其与微观结构的关系。结果表明,当...为分析黄河源区高寒草甸植物单根的抗拉力学性质及其护岸的微观力学机理,以华扁穗草、线叶嵩草和金露梅3种优势滨河植物为研究对象,通过开展单根拉伸试验和石蜡切片试验,定量分析3种植物单根力学特性及其与微观结构的关系。结果表明,当根径在<0.5 mm、0.5~1.0 mm和>1.0 mm 3个根径级别时,3种植物单根抗拉力和延伸率均随根径增大而增大;单根抗拉强度和杨氏模量均随根径增大而减小;根系应力-应变曲线表现为单峰曲线。灌木金露梅单根平均抗拉强度是草本植物华扁穗草和线叶嵩草的1.56倍和1.25倍,华扁穗草单根平均延伸率是线叶嵩草和金露梅的1.06倍和1.36倍。草本植物单根抗拉强度主要与其维管柱面积占比有关;而灌木金露梅单根抗拉强度主要与其周皮和次生木质部面积占比有关。综合来看,华扁穗草和线叶嵩草根系抵抗变形的能力较强,主要发挥加筋和减缓河岸变形、破坏的作用;而金露梅刚度强、抗拉强度较大,主要发挥固土护岸的作用。研究结果可为筛选黄河源区优势护岸植物提供科学依据。展开更多
基金the financial supports from the Chaipattana FoundationKasetsart University Research and Development Institute(KURDI)the scholarship for his PhD studies provided by the Faculty of Engineering,Kasetsart University
文摘Root tensile strength is an important factor controlling the performance of bio-slope stabilization works. Due to evapotranspiration and climate factors, the root moisture content and its suction can vary seasonally in practice and may not equal soil suction. The influences of suction and root moisture contents were investigated on Chrysopogon zizanioides(vetiver grass) root tensile strength. The root specimens were equilibrated with moist air in different suction conditions(0, 10, 20, and 50 kPa), prior to root tension tests. The root-water characteristic curve or relationship between root moisture and suction, was determined. The increase in suction resulted in decreased tensile strengths of the grass roots, particularly those with diameter of about 0.2 mm, which constituted 50.7% of all roots. For 1 mm roots, the tensile strength appeared to be unaffected by suction increase. The average root tensile strengths were used to estimate the root cohesion in slope stability analysis to find variation of safety factors of a bioengineered slope in different suction conditions. The analysis showed that the critical condition of slope with the lowest factor of safety would happen when the soil suction was zero and the root suction was high. Such condition may occur during a heavy rain period after a prolonged drought.
文摘为分析黄河源区高寒草甸植物单根的抗拉力学性质及其护岸的微观力学机理,以华扁穗草、线叶嵩草和金露梅3种优势滨河植物为研究对象,通过开展单根拉伸试验和石蜡切片试验,定量分析3种植物单根力学特性及其与微观结构的关系。结果表明,当根径在<0.5 mm、0.5~1.0 mm和>1.0 mm 3个根径级别时,3种植物单根抗拉力和延伸率均随根径增大而增大;单根抗拉强度和杨氏模量均随根径增大而减小;根系应力-应变曲线表现为单峰曲线。灌木金露梅单根平均抗拉强度是草本植物华扁穗草和线叶嵩草的1.56倍和1.25倍,华扁穗草单根平均延伸率是线叶嵩草和金露梅的1.06倍和1.36倍。草本植物单根抗拉强度主要与其维管柱面积占比有关;而灌木金露梅单根抗拉强度主要与其周皮和次生木质部面积占比有关。综合来看,华扁穗草和线叶嵩草根系抵抗变形的能力较强,主要发挥加筋和减缓河岸变形、破坏的作用;而金露梅刚度强、抗拉强度较大,主要发挥固土护岸的作用。研究结果可为筛选黄河源区优势护岸植物提供科学依据。
