基于模型试验的涉水堆积体岸坡变形-破坏模式研究

Model Test on Deformation and Failure Modes of Accumulation Slope under the Action of Reservoir Water

为了进一步探究涉水堆积体岸坡变形-破坏模式,自主设计制作了模型试验平台,选取三峡库区碎石土样,测定了土样基本力学特性,开展了水位升降作用下堆积体岸坡的物理模型试验。依据试验现象,重点分析了不同坡度的岸坡模型在不同水位作用条件下的破坏模式。结果表明:坡度对岸坡变形-破坏特征影响显著,坡度较大(50°及60°)时,在水位上升期间便发生大规模塌岸现象,变形-破坏模式表现为水位上升→剥蚀、淘空塌岸→下错平台→整体滑塌→次稳定状态;坡度为40°时,在水位下降期间发生了较大规模的滑动破坏,对应变形-破坏模式为水位上升→坡体沉降→贯穿裂隙形成→水位下降→贯穿裂隙扩展滑面形成→整体滑移;岸坡坡度较小(35°)时,多次升降循环中并未出现明显的变形-破坏迹象。

In the aim of investigating the deformation and failure modes of water-involved accumulation slope, physical model test on accumulation slope was conducted under the action of reservoir water level fluctuation. A model test platform with the base plate adjustable was designed and manufactured independently. And the basic me-chanical properties of soil samples collected from Three Gorges Reservoir were determined. Results show that slope gradient has significant influence on the characteristics of slope deformation and failure： large-scale bank collapse occurrs during the rise of water level when slope gradient is large （50° and 60°） ,and the deformation failure mode is water level raising→denudation and tunneling←→bank collapse →sinking platform →integral sliding →metastable state; whereas when the slope gradient is 40°,large sliding failure occurs during the water level drawdown,and the corresponding deformation failure mode is water level raising→slope settlement→ crack penetration→drop of water level→propagation of crack penetration←→formation of slip surface →global slip ; when the slope gradient is small （35°）,there is no obvious deformation and failure in many times of water level fluctuation cycle.