北麓河青藏公路沿线多年冻土区热融滑塌型边坡植被防护力学效应研究

    STUDY ON THE MECHANICAL EFFECT OF VEGETATION PROTECTION OF THAW SLUMPING SLOPE IN PERMAFROST AREA OF BEILUHE REGION ALONG THE QINGHAI-TIBET HIGHWAY

      摘要
    • 摘要: 为评价青藏公路沿线多年冻土区高寒草甸和人工种植植物固土护坡力学贡献，本研究选取位于青藏公路沿线北麓河地区一处热融滑塌灾害作为研究区。以原生草甸(主要植物种为嵩草(Carex myosuroides Vill.)和藏嵩草(Kobresia tibetica Maxim.))和人工种植垂穗披碱草(Elymus nutans Griseb.)、星星草(Puccinellia tenuiflora(Griseb.)Scribn. & Merr.)、冰草(Agropyron cristatum(L.)Gaertn.)、早熟禾(Poa annua L.)、碱茅(Puccinellia distans(L.)Parl.)和中华羊茅(Festuca sinensis Keng ex S.L.Lu)等6种生长期为1 a草本为研究对象，通过开展室内原状根-土复合体剪切试验，探讨了草本根系增强热融滑塌型边坡体抗剪强度作用贡献，并采用静力平衡法对该热融滑塌型边坡稳定性进行了评价。主要得到如下结果：通过室内洗根试验得到根-土复合体试样平均含根量由高至低依次为原生草甸(33.33 mg·cm-3)、垂穗披碱草(16.95 mg·cm-3)、早熟禾(13.12 mg·cm-3)、中华羊茅(5.80 mg·cm-3)、冰草(3.89 mg·cm-3)、星星草(3.15 mg·cm-3)、碱茅(2.86 mg·cm-3)；平均株高由高至低依次为垂穗披碱草(10.93 cm)、原生草甸(9.64 cm)、冰草(6.88 cm)、早熟禾(5.22 cm)、中华羊茅(3.90 cm)、碱茅(3.86 cm)、星星草(2.90 cm)；区内原生草甸和6种人工种植草本根-土复合体抗剪强度均显著高于不含根系素土，其中原生草甸和人工种植垂穗披碱草根系增强土体抗剪强度作用增幅相对较大，分别为42.17%和30.96%；由静力平衡法计算得到含根系边坡安全系数均高于不含根系素土边坡，边坡安全系数由大至小依次为原生草甸(1.47)、垂穗披碱草(1.39)、早熟禾(1.38)、冰草(1.37)、碱茅(1.36)、星星草(1.32)、中华羊茅(1.32)、素土(0.96)。该研究结果对于有效防治青藏公路沿线北麓河地区热融滑塌灾害，同时为进一步有效防治青藏公路沿线热融滑塌灾害引发的水土流失、草地退化等灾害提供理论依据和实际指导。

       

      Abstract: This study selected a thaw slumping slope in the Beiluhe region along the Qinghai-Tibet Highway as the research area, to evaluate the mechanical contribution of alpine meadow and artificial planting plants to soil reinforcement and slope protection in permafrost region. The native meadow plants such as Carex myosuroides Vill. and Kobresia tibetica Maxim. and 6 kinds of herbs with growth period of 1 a such as Elymus nutans Griseb., Puccinellia tenuiflora(Griseb.)Scribn. & Merr., Agropyron cristatum(L.)Gaertn., Poa annua L., Puccinellia distans(L.)Parl., Festuca sinensis Keng ex S.L.Lu were used as the main research objects. Based on the shear test of root-soil composite system in laboratory, the contribution of herbs roots to enhance the shear strength of thaw slumping soil was discussed, and the stability of thaw slumping slope was evaluated by static equilibrium method. The main results are as follows: by conducting the root-washing experiments, the average root content of the root-soil composite system sample from high to low is as follows: native meadow(33.33 mg·cm-3), Elymus nutans Griseb. (16.95 mg·cm-3), Poa annua L. (13.12 mg·cm-3), Festuca sinensis Keng ex S.L.Lu(5.80 mg·cm-3), Agropyron cristatum(L.)Gaertn. (3.89 mg·cm-3), Puccinellia tenuiflora(Griseb.)Scribn. & Merr. (3.15 mg·cm-3) and Puccinellia distans(L.)Parl. (2.86 mg·cm-3). The average height of plant in the study area from high to low is Elymus nutans Griseb. (10.93 cm), native meadow(9.64 cm), Agropyron cristatum(L.)Gaertn. (6.88 cm), Poa annua L. (5.22 cm), Festuca sinensis Keng ex S.L.Lu(3.90 cm), Puccinellia distans(L.)Parl. (3.86 cm) and Puccinellia tenuiflora(Griseb.)Scribn. & Merr. (2.90 cm). The shear strength of native meadow and 6 kinds of artificial herbs root-soil composite system in the study area was significantly higher than that of plain soil. The increase of the shear strength of the soil enhanced by the roots of the native meadow(42.17%) and the artificial planting Elymus nutans Griseb. (30.96%) is relatively larger than the others. The safety factor of the slope with roots calculated by the static equilibrium method is higher than that of the plain soil slope. The safety factor of slope from large to small is native meadow(1.47), Elymus nutans Griseb. (1.39), Poa annua L. (1.38), Agropyron cristatum(L.)Gaertn. (1.37), Puccinellia distans(L.)Parl. (1.36), Puccinellia tenuiflora(Griseb.)Scribn. & Merr. (1.32), Festuca sinensis Keng ex S.L.Lu(1.32) and plain soil(0.96). The results of this study provide theoretical basis and practical guidance for the effective prevention and treatment of thaw slumping slopes in the Beiluhe region and the soil erosion, grassland degradation and other disasters caused by thaw slumping along the Qinghai-Tibet Highway.

       

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