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大兴安岭土壤抗剪强度及影响因素研究

Study on Soil Shear Strength and Influencing Factors in Daxing’an Mountains

  • 摘要: 采用摩尔库伦强度理论,通过设置多个对照组进行室内三轴试验,研究大兴安岭地区棕色针叶林土壤和暗棕壤的物理性质、土壤抗剪强度差异及相关影响因素。研究结果显示,2个研究对象及自身不同土层之间在含水率、土壤容重及机械组成方面存在不同程度的差异,土壤抗剪强度指标受土壤容重、机械组成、是否添加根系的影响,其中土壤抗剪强度与粉粒含量呈显著负相关(R=-0.755 3),与砂粒含量呈显著正相关(R=0.978 4)。黏聚力与砂粒含量呈显著正相关(R=0.760 1),内摩擦角与黏粒含量呈显著正相关(R=0.836 0),与粉粒含量呈显著负相关(R=-0.815 9);根系的“加筋”作用有助于土壤抗剪强度的提高,使得棕色针叶林土壤和暗棕壤的内摩擦角增大,棕色针叶林土壤的黏聚力降低,暗棕壤的黏聚力升高,导致两者土壤抗剪强度出现不同程度的变化,但在高径向围压状态下,2种土壤均表现出抗剪强度增大的结果。

     

    Abstract: Based on the Mohr-Coulomb strength theory, indoor triaxial tests was conducted by setting up multiple control groups to study the physical properties, shear strength differences and related influencing factors of brown coniferous forest soil and dark brown soil in Daxing’an Mountains. The results showed that there were differences in water content, soil bulk density and mechanical composition between the two research objects and different soil layers. Soil shear strength was affected by soil bulk density, mechanical composition and root addition. Among them, soil shear strength was significantly negatively correlated with silt content(R=-0.755 3) and positively correlated with sand content(R=0.978 4). The cohesion was significantly positively correlated with the sand content(R=0.760 1), the internal friction angle was significantly positively correlated with the clay content(R=0.836 0), and was significantly negatively correlated with the silt content(R=-0.815 9). The ‘ reinforcement’ effect of root system contributed to the improvement of soil shear strength, which increased the internal friction angle of brown coniferous forest soil and dark brown soil, decreased the cohesion of brown coniferous forest soil, and increased the cohesion of dark brown soil, resulting in varying degrees of changes in soil shear strength. However, both soils showed increasing shear strength under high radial confining pressure.

     

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