降雨条件下湖南省红层地区浅层土坡失稳机理研究

Study on instability mechanism of shallow soil slopes in the red beds of Hunan Province under rainfall conditions

摘要:

红层是典型的“易滑地层”，在降雨条件下很容易发生浅层土质滑坡，因此研究红层地区浅层土质边坡在降雨条件下的稳定性十分重要。本研究以湖南省红层区浅层土质边坡为例，采用修正Green-Ampt入渗模型，对不同坡度、降雨强度、饱和渗透系数和初始含水率条件下的红层地区浅层土质边坡的稳定性进行研究，分析得到了各因素对边坡稳定性的影响规律。边坡坡度<45°时，安全系数随坡度增大而减小，边坡坡度>60°时，安全系数随坡度增大而增大；湿润锋随降雨强度的变化不明显，安全系数随降雨强度的增加变化不明显；随着饱和渗透系数的增加，湿润锋深度增加，边坡安全系数减小；安全系数随初始含水率的增加而减小。研究结果可为红层地区边坡防护工程提供一定的理论依据和实践指导。

关键词:红层;土质边坡;边坡稳定性;降雨入渗;修正Green-Ampt模型

Abstract:

Red beds are typically considered as “prone-to-slide strata”， and shallow soil landslides can easily occur under rainy conditions. Therefore， it is of great importance to study the stability of shallow soil slopes in red bed areas under rainfall conditions. In this research，the shallow soil slopes in the red bed areas of Hunan Province is taken as an example， the stability of shallow soil slopes in red bed areas under different slope gradients， rainfall intensities， saturated hydraulic conductivities， and initial water contents is investigated by employing the modified Green-Ampt infiltration model， the specific impact patterns of these factors on slope stability is also analyzed. When the slope gradient is less than 45°， the safety factor decreases as the slope increases； when the slope gradient is greater than 60°， the safety factor increases with the slope. The wetting front depth changes insignificantly with the rainfall intensity， and the safety factor changes insignificantly with the rainfall intensity； the depth of the wetting front increases and the safety factor of the slope decreases as the saturated hydraulic conductivity increases； the safety factor decreases as the initial water content increase. The results can provide a theoretical basis and practical guidance for slope protection engineering in red bed areas.

Key words:red bed;soil slope;slope stability;rainfall infiltration;modified Green-Ampt model