考虑降雨入渗条件的植被边坡稳定性评价

为了研究降雨对植被边坡稳定性的影响,利用改进的Green-Ampt模型,在考虑植被水力作用和饱和区径流基础上,推导出了降雨入渗条件下植被边坡的湿润锋深度计算公式,并采用极限平衡法计算出了植被边坡不同潜在滑动面上的抗滑稳定安全系数,对多层非饱和土植被边坡稳定性进行分析评价。结果表明:考虑植被水力影响和饱和区径流的多层非饱和土植被边坡的入渗模型,更加实用,可更加准确地对降雨作用下植被边坡进行稳定性评价;湿润锋深度随着降雨的持续时间增加而增大,浸润锋经过土层交界处时出现突变现象,根系粉质砂土层的湿润锋深度增幅小于粉质砂土层的湿润锋深度增幅的1.5%~11.8%;4个潜在滑动面处的抗滑稳定安全系数在降雨早期随着降雨持续时间的增加而逐渐减小;粉质砂根土复合层的抗滑稳定安全系数比粉质砂土层的抗滑稳定安全系数提高了12.3%~35.5%;根土层与土层交界面处不易发生失稳破坏,而土层与土层交界面处的抗滑稳定安全系数会出现急剧变化,易发生失稳破坏。

Stability of Vegetated Slope under the Combined Action of Vegetation's Hydraulic Effect and Runoff in Saturated Zone in Consideration of Rainfall Infiltration

The aim of this research is to explore the impact of rainfall on the stability of vegetated slope. The calculation formula for the wetting front depth of vegetated slope under rainfall infiltration was deduced using the improved Green-Ampt model with the hydraulic effect of vegetation and the runoff in saturated zone into consideration. The factor of safety of different potential sliding surfaces was calculated by using the limit equilibrium analysis method; thereafter, the stability of multi-layer vegetated unsaturated soil slope was analyzed and evaluated. Results indicate that the present infiltration model of multi-layer vegetated unsaturated soil slope which considers the hydraulic effect of vegetation and the runoff in saturated zone is practical, and could accurately evaluate the stability of vegetated slope under rainfall. The depth of wetting front increased with the expansion of rainfall duration, and the wetting front changed suddenly when the wetting front passed the boundary of soil layer. The increment of wetting front depth in root-silty sandy soil layer was smaller than that in silty sandy soil layer by 1.5%-11.8%. The anti-slip safety factor of the four potential sliding surfaces decreased with the increase of rainfall duration in the early stage of rainfall. The safety factor of vegetation-silty sand layer increased by 12.3%-35.5% compared with that of silty sand layer. Instability and damage were not easy to occur at the interface between root-soil layer and soil layer; but were prone to happen at the interface between soil layer and soil layer as the safety factor changed sharply.