土石山区护坡草本植物根系抗拉力学特性

为了解山西省土石山区护坡植物的根系抗拉力学特性,对比选择最适宜的水土保持物种.对其边坡上黑麦草(Lolium perenne L.)、香根草(Vetiveria zizanioides L.)、百喜草(Paspalum notatum Flugge)3种护坡植物的根系开展抗拉力学试验,研究3种植物根系最大抗拉力、极限抗拉强度以及弹性模量随直径及根长大小变化的规律.研究结果显示:根长一定时,3种植物的最大抗拉力随直径的增加而增加,单根极限抗拉强度随根系直径的增大而减小;而直径一定时,根系最大抗拉力和极限抗拉强度随根系长度的增大而减小;弹性模量值随着根径和根长增大呈下降的趋势.3种植物根系平均最大抗拉力关系为:香根草(16.258 N)＞黑麦草(11.734N)＞百喜草(4.891 N);平均极限抗拉强度关系为:百喜草(116.226 MPa)＞黑麦草(50.839 MPa)＞香根草(49.650MPa);平均弹性模量分别为:百喜草(20.392 MPa/mm)＞香根草(3.257 MPa/mm)＞黑麦草(3.245 MPa/mm).结果表明这3种植物中百喜草根系的固土能力最好,在选择最为适宜的水土保持物种时可优先考虑.研究结果可为土石山区水土保持研究提供一定的科学依据.

Root tensile properties of the herbaceous plants for slope protection in earth-rocky mountain area,northern China

Background] Landslides caused by soil erosion are common natural geological disasters all over the world.Planting plants on hillsides is an effective project to conserve soil and water during urban construction and mountain development.The mechanical properties of plants are affected by many factors,such as root diameter,root length and rate of water content,as well as the loading ways,loading speed,logging time,etc.Effect of root length and diameter on root tensile properties of herbaceous plants in earth-rocky mountain area is still scarce.Methods] This study aims at three slope protection plants:Lolium perenne L.,Vetiveria zizanioides L.and Paspalum notatum Flugge in earth-rocky mountain areas in Shanxi Province,northern China.Three different root lengths:60,80 and 100 mm were selected in this study.Root tensile tests were conducted with a WDW-5 universal electronic testing system.In the tests,maximum tensile resistance,ultimate tensile strength and elastic modulus with changing root diameter and root length were measured and analyzed.Results] The root diameter of V.zizanioides L.and L.perenne L.mainly varied in the range of 0.2-1.0 mm and P.notatum Flugge varied in the range of 0.1-0.4 mm,and the average values of the diameters were 0.639,0.557 and 0.230 mm respectively.The average maximum tensile resistance of the three species was in the order:V.zizanioides L.(16.258 N) ＞ L.perenne L.(11.734 N) ＞ P.notatum Flugge (4.891 N).The average tensile strength ranked as P.notatum Flugge (116.226 MPa) ＞ L.perenne L.(50.839 MPa) ＞V.zizanioides L.(49.650 MPa).The average elastic modulus was in order as P.notatum Flugge (20.392 MPa/mm) ＞ V.zizanioides L.(3.257 MPa/mm) ＞ L.perenne L.(3.245 MPa/mm).The elastic modulus of P.notatum Flugge was about six times larger than the others.With certain root length,the maximum root tensile strength of the three plants decreased with root diameter increasing.Within certain root diameter,the maximum root tensile strength decreased with root length increasing.In addition,the elastic modulus decreased with both root diameter and length increasing.Conclusions] According to the results,P.notatum Flugge has the best ability of soil fixation and slope protection among the studied three species.It can be a suitable species to maintain soil and water.The results provide a data basis for slope protection and soil and water conservation with vegetation in earth-rocky mountain areas.