降雨入渗对宁南山区黄土梯田边坡稳定性的影响

Rainfall Infiltration:Effects on Slope Stability of Loess Terraces in Mountainous Area of Southern Ningxia

为了研究降雨入渗对宁南山区黄土梯田边坡稳定性的影响。采用ABAQUS软件建立降雨入渗下的宁南山区黄土梯田边坡稳定性有限元模型,研究了水平梯田、隔坡梯田、原始边坡(对照)3种边坡类型,在降雨入渗强度(28~38 mm/h)和边坡坡度(15°—30°)下的破坏时间和安全系数的变化规律。结果表明:降雨入渗下,黄土梯田边坡的破坏时间随降雨入渗强度的增大而减小,且呈幂函数关系,水平梯田的破坏时间显著高于隔坡梯田和原始边坡;安全系数也随降雨入渗强度的增大而减小,但呈线性关系,水平梯田的安全系数与隔坡梯田和原始边坡并无显著差异。降雨条件下,修筑梯田能增加浅层梯田边坡的稳定性,而对于深层梯田边坡的稳定性影响不大。

The paper aims to study the effects of rainfall infiltration on the slope stability of loess terraces in mountainous area of southern Ningxia.We established a finite element model for the stability analysis by using the software ABAQUS,and studied the variation of failure time and safety factors of 3 different types of terraced slopes:the level terrace,alternate terrace and original slope(control)under different rainfall infiltration intensities(28-38 mm/h)and the slope gradient(15°-30°).The results showed that:the failure time of the terraced slope decreased with the increase of rainfall infiltration intensity and satisfied the power function relation;the failure time of the level terrace was significantly higher than that of the alternate terrace and original slope;the safety factors of the terraced slope decreased with the increase of the rainfall infiltration intensity too,but satisfied the linear function relation;the safety factors of the level terrace had no significant difference between the alternate terrace and original slope.Under the condition of rainfall,the construction of loess terraces can increase the stability of shallow terrace slope,but has little effect on the stability of deep terrace slope.