Abstract

The mechanism of toppling deformation and failure is important in the stability analysis of anti-dip layered rock slopes, especially in a complex hydrogeological environment. In this paper, the flexural failure model is proposed for describing the mechanical behavior of toppling rock slope using the cantilever beam theory. A method for safety evaluation, considering the action of hydrodynamic force from groundwater, is developed. This model is then applied to conduct a case study of a toppling rock slope at a hydropower station on the Lancang River. The results show that the variation of reservoir water level increases both the tensile stresses and the deflections of rock slabs, which is manifested macroscopically by flexural displacements and failure. Based on the failure surfaces, the slope can be divided into three parts: toppling zone, creep zone, and shear zone. The failure mode of toppling rock slope is a combination of shear and toppling. Under the combined action of earthquake and rapid water drawdown, the toppling rock slope is at risk of shear instability at the leading edge; hence monitoring should be strengthened and prevention measures should be taken.

摘要

倾倒变形破坏机理在反倾层状岩质边坡稳定性分析中具有重要意义，尤其是在复杂的水文地质环境中。本文利用悬臂梁理论提出了描述倾倒岩石边坡力学行为的弯曲破坏模型。开发了一种考虑地下水水动力作用的安全评价方法。然后应用该模型对澜沧江水电站倾倒的岩石边坡进行案例研究。结果表明，水库水位的变化增加了岩板的拉应力和挠度，宏观上表现为挠曲位移和破坏。根据破坏面，边坡可分为三个部分：倾倒区，蠕变区和剪切区。倾倒岩质边坡的破坏模式是剪切和倾倒相结合的破坏形式。在地震和快速降水的共同作用下，倾倒的岩质边坡存在前缘剪切失稳风险；因此，应加强监测，采取预防措施。