土工合成材料加筋边坡宏细观机理模型试验研究

Model tests on macro-mesoscopic mechanism of geosynthetic-reinforced slopes

通过包裹式加筋边坡模型试验对加筋边坡宏观变形模式、宏观力学性状、筋土界面细观作用和剪切破坏带处土颗粒运动进行研究,分析土工合成材料加筋边坡宏细观机理。砂土加筋边坡由于加筋体的存在,宏观变形上呈现为类似黏性土边坡的整体滑移破坏模式,出现圆弧状剪切破坏带;坡顶上部基础p–s曲线类似基础整体剪切破坏弹性、弹塑性和塑性破坏三阶段,曲线各阶段变化与主剪切破坏带整体发展有密切关系;细观上筋土界面处筋材与土颗粒摩擦和咬合作用提供"似黏聚力";"主剪切破坏带"内颗粒的滚动摩擦、"过渡区"内颗粒的滚动摩擦和滑动摩擦和"稳定区"内颗粒的咬合作用构成整个剪切破坏带抗滑阻力。筋土界面处筋材与土颗粒相互作用所提供的"似黏聚力"和主剪切破坏带的发展和贯通所提供的滚动摩擦和滑动摩擦是形成加筋砂土边坡整体滑移、改变整个边坡破坏模式的内在原因。

Model tests on a geosynthetic-reinforced slope in macro- and meso-scale are performed to investigate its deformation models, meso-interaction between geosynthetic and soil particles, particle movement in the shear zone, as well as macro- mesoscopic mechanism. Because of the geosynthetic in the sand slope, a shear zone in arc occurs just like the failure surface mode of clay slope in macro-scale. Three stages can be found in the p-s curve of foundation： elastic stage, elastic-plastic stage and plastic stage. The transformation ofp-s curve relates to the development of the main shear zone. The ＂cohesion＂ in the sand slope is provided by friction and occlusive force in the interface between sand particle and geosynthetic in meso-scale. The whole sliding resistance is composed by the friction in the ＂main shear zone＂, ＂transitional zone＂ and ＂steady zone＂. The intrinsic factors which form and change the failure surface of the geosynthetic-reinforced slope are the ＂cohesion＂ provided by friction and occlusive force in the interface between sand particle and geosynthetic and the friction force during the development of whole shear zone.