寒旱环境盐生植物根系固土护坡力学效应及其最优含根量探讨

 本项研究以大柴旦盐湖区及其周边地区为例，选取海韭菜(Triglochin maritima Linn.)、赖草(Leymus secalinus Tzvel.)、毛穗赖草(Leymus paboanus Claus.)、无脉苔草(Carex enervis C. A. Mey.)等4种优势盐生植物，对其单根进行了单根拉伸试验以及4种植物根–土复合体抗剪强度试验。分别获得了4种植物单根最大抗拉力和单根抗拉强度；通过对4种盐生植物根–土复合体在不同含根量梯度下的直接剪切试验，探讨了根系对土体抗剪强度增强作用以及根–土复合体的最优含根量。由单根拉伸试验结果表明，4种植物单根抗拉力值为4.67～10.97 N，单根抗拉强度值为12.32～49.99 MPa，且4种植物单根抗拉强度由大至小依次为赖草、毛穗赖草、无脉苔草、海韭菜；4种植物根–土复合体扰动试样黏聚力值为10.44～27.42 kPa，不含根素土试样黏聚力值为8.10 kPa，与不含根系素土相比，根–土复合体的黏聚力增长量为2.34～19.32 kPa，其增幅为28.89%～238.52%；根系增强土体抗剪强度存在最优含根量，根–土复合体试样中的含根量处于最优含根量时，4种植物根-土复合体的抗剪强度为相对最大值，其黏聚力值为17.94～27.42 kPa，黏聚力由大至小依次为海韭菜、赖草、毛穗赖草、无脉苔草。该研究成果对大柴旦盐湖区以及与该区地质条件相似的其他地区开展利用盐生植物增强土体抗剪强度，且对于开展有效防治土体侵蚀和地表水土流失等地质灾害的发生具有理论价值和实际意义。

RESEARCH ON THE MECHANICAL EFFECTS OF HALOPHYTES ROOTS IN SLOPE PROTECTION AND THE OPTIMAL ROOT CONTENT IN COLD AND ARID ENVIRONMENT

In this research，Da Qaidam salt lake region and the surrounding areas was taken as the experimental area. Tension tests of single roots as well as shear strength test of the root-soil composite system of the four dominant halophytes(Leymus secalinus Tzvel.，Leymus paboanus Claus.，Carex enervis C. A. Mey. and Triglochin maritima Linn) were performed. The maximum tensile resistance and the corresponding tensile strength for the 4 species have been determined. In addition，a study on how roots increase the shear strength of soil and the optimal root content through the direct shear test for root-soil composite system for four halophytes was also carried out. The results of single root tensile test shows that the single root tensile resistance for four halophytes is 4.67～10.97 N，the single root tensile strength for four halophytes is 12.32～49.99MPa，meanwhile，the descending order of the tensile strength for the 4 halophytes is Leymus secalinus Tzvel.＞Leymus paboanus Claus.＞Carex enervis C. A. Mey.＞Triglochin maritima Linn.. The direct shear test shows that the cohesion force of the root-soil composite system for the disturbed samples of the four halophytes ranges in 10.44～27.42 kPa and that of soil without root is 8.10 kPa. Compared with soil without roots，the cohesion force of four root-soil composite system increase by 2.34～19.32 kPa and with an increase percentage of 28.89%～238.52%；roots can improve the shear strength of soil and there’s an optimal root content with which the shear strength can reach the peak value，and with the optimal root content，the corresponding cohesion force of the root-soil composite system for the 4 halophytes ranges in 17.94～27.42 kPa and the descending order is Triglochin maritima＞Leymus secalinus＞Leymus paboanus＞Carex enervis. The study has a theoretical and practical significance for Da Qaidam salt lake area and other areas having the similar geological condition in increasing shear strength by roots of halophytes，and meanwhile the study is conducive in the control of geological hazards，like water loss and soil erosion.