香根草固土护坡工程特性初步研究

Preliminary study on engineering properties of vetiver on slope protection

香根草的根系长度和抗拉力或强度都较大,单根的抗拉力或强度的平均值为12.4N或69.7MPa,而且群根效应显著,对边坡起着“活着的土钉”作用。深扎广布于坡体中的根系网,显著改善边坡土体的物理力学性质,明显提高边坡土体的强度及稳定性,可较大幅度地降低作用于护坡挡墙上的主动土压力强度(总主动土压力的减少值大于15%);浓密成丛的香根草可分散径流和减少径流量,有效降低降雨与径流对坡面的冲击力及侵蚀量,对坡面起到较好的防护作用;此外,光合作用强、速生快长的香根草及其发达根系网的吸收与蒸腾作用,可降低边坡土体中的含水量及孔隙水压力,增强土中吸力,进而提高边坡土体的强度,增强边坡的稳定性;穿扎广布于坡体土中的香根草根系网系统,类似“活性钢筋网”,与边坡体固结共同作用、融合胶结构成类似原位复合的重力墙,可较好地防止及控制边坡位移或失稳的发生。初步研究表明;香根草护坡的力学效果较为理想,且具有较强的经济效益及环境效益优势。

Vetiver has long roots and a great tensile strength. The average tensile strength of a single one can be 12.4N. Besides it has a significant effect of one group of roots and has a great influence on a slope just like ＂living soil nail＂. The deep and wide root nets can improve the physical and mechanical properties of slope soil body; improve the intensity and stability of slope soil body; and redece the active earth pressure acting on the retaining wall（the total reduction of the active earth pressure is much more than 15 % ）. The dense vetiver can disperse the surface flow and reduce the surface ruboff amount reduce the shock power and the corroding amount effectively caused by raining and surface runoff, and has a good protecting effect on slope surface. Besides, with the strong photosynthesis and root network system which has a effect of absorption and transpiration, the fast growing vetiver can reduce the water content and the pore water pressure of solpe soil body; meanwhile, they also can enhance the suction force of earth, so the intensity and stability of soil body is improved. Furthermore, the wide spread vetiver zizanioides root nets system, like ＂the active mesh reinforcement＂, combined with the consolidation of slope soil body, effected by glued function, form a in situ compound similar gravity retaining wall, which can prevent the displacement or loss of stability effectively, so the preliminary study indicate that it has a good advantage on economic benefits and environmental benefits using vetiver zizanioides to protect slope, meanwhile its mechanical effect of slope protection is perfect.