不同类型土壤-柠条根系复合抗剪力学特性的比较

Comparison of Composite Shear Mechanical Properties of Different Types of Soil-like caragana korshinskii Root

为揭示柠条根系固土抗蚀机理,以柠条锦鸡儿与低液限粘土、砒砂岩风化土、含细粒土砂3种土壤类型的根土复合体做为对象进行室内直剪试验,研究3种土壤类型的柠条根土复合体抗剪强度及强度指标,分析其差异性。结果表明:3种不同土壤类型下柠条根土复合体剪切规律均服从摩尔-库仑强度破坏准则。0.05显著水平下,12.5 kpa下根系提高土体抗剪强度优于25 kpa。抗剪强度、残余抗剪强度及二者的强度指标均为柠条根与3种土壤类型根土复合体优于相应素土。抗剪强度、残余抗剪强度、粘聚力及残余粘聚力大小排序为:低液限粘土根土复合体>砒砂岩风化土根土复合体>含细粒土砂根土复合体,内摩擦角和残余内摩擦角大小排序为:含细粒土砂根土复合体>砒砂岩风化土根土复合体>低液限粘土根土复合体。粘聚力、残余粘聚力的增长率区间为9.97%~45.78%,内摩擦角和残余内摩擦角的增长率区间为-4.09%~2.40%。根会增强土壤抗剪强度及残余抗剪强度。柠条根系对提高低液限粘土的抗剪特性作用效果最明显,提升效果最好。粘聚力在根土复合体抗剪强度、残余抗剪强度的增加中起主要作用。

In order to reveal the mechanism of soil erosion resistance of Caragana Korshinskii roots,taking the Caragana korshinskii root-soil composite systems with low liquid limit clay,soft sandstone weathered soil and fine grained sand as the research objects,the shear strength and strength index of them and their differences were analyzed.The results showed that the shear law of the Caragana korshinskii root-soil composite systems under three different soils all obeyed the More-Coulomb strength failure criterion.At the significant level of 0.05,the shear strength of soil increased by roots at 12.5 kpa was better than that at 25 kpa.The shear strength,residual shear strength and the strength indices of the three Caragana korshinskii root-soil composite systems were all better than that of the corresponding plain soil.The order of shear strength,residual shear strength,cohesion and residual cohesion among the three root-soil composite system was presented by root-low fluid limit clay>root-soft sandstone weathered soil>root-fine grained sand.The order of internal friction angle and residual internal friction angle of them were showed by root-fine grained sand>root-soft sandstone weathered soil>root-low fluid limit clay.The growth ranges of cohesive force and residual cohesive force were 9.97%-45.78%,and the growth ranges of internal friction angle and residual internal friction angle were-4.09%-2.40%.Above all,the roots could enhance the soil shear strength and residual shear strength.The Caragana Korshinskii roots had the most obvious and the best effect on improving the shear properties of low liquid limit clay.The cohesiveness was an important role on increasing the shear strength and residual shear strength of the root-soil composite system.