组合根系加固坡土的直剪试验及数值模拟

Direct shear tests and numerical simulation on slope soils reinforced by composite roots

随着生态护坡技术的不断发展,植被根系固土护坡的作用越来越受到重视。护坡植物根系大多主根与侧根相辅相成,因此针对单根的剪切试验往往不能正确反映真实环境中根系固土的作用机制。为揭示真实根系固土的力学机制,量化根系倾角对坡土的强度影响,开展了侧根倾角分别为30°,45°,60°的组合根系加固坡土的大型直剪试验及数值模拟。结果表明:组合根系能明显提高土体抗剪强度,试验用的根系增加的抗剪强度最大为6.36 kPa;外部剪切荷载主要由前侧根承担,组合根系对土体抗剪强度的贡献依次为前侧根、主根、后侧根;随侧根倾角的增加,前侧根受到的轴向拉力增加,前侧根产生的拉伸变形增大,前侧根附近塑性区分布范围增大,表明前侧根能调动周围更大范围的土体抵抗剪切,根系固土效果增强。

With the development of bioengineering stabilization techniques for slope protection,the role of root reinforcement in slope protection has been paid more and more attention to.The primary root and the lateral root are complementary to each other in most root systems.Therefore,the shear tests with single root often fail to reflect the mechanism of root-soil reinforcement in the real vegetated slopes.In order to reveal the reinforcement mechanism of composite roots and quantify the influences of root angle to the strength of slope soils,the large-scale direct shear tests and numerical simulations are carried out to study the effects of composite roots on the shear strength of soils,with lateral root angles of 30°,45°and 60°.The results show that composite roots can obviously improve the shear strength of soils,and the maximum shear strength increased by the roots is 6.36 kPa.The external shear load is primarily carried by the lateral root opposite to the shear direction(i.e.,the front lateral root),and the consequence of the contribution of composite roots to the shear strength of soil in values is as follows:the front lateral root,the primary root and the posterior lateral root.With the increase of lateral root angle,the axial force and the tensile deformation on the front lateral root increases,and the distribution of the plastic zone near the front lateral root increases,which shows that the front lateral root can mobilize more soils around it to resist shear force,and the soil reinforcement effects of composite roots are enhanced.