非饱和土边坡饱和区降雨强度-时间临界曲线

Critical Curve of Rainfall Intensity-Time for Saturated-Zone in Unsaturated Soil Slope

为研究降雨入渗边坡产生饱和区的临界条件,使用基于MVG模型的土体饱和度表征降雨强度的计算方程.当土表面饱和度首次达到0.9以上时,饱和度持续稳定在0.9±0.005为饱和区出现的临界判据,数值计算得出土柱和边坡的饱和区临界降雨强度与降雨时间.通过数据拟合构建了饱和区降雨强度-时间临界曲线模型,分析了不同坡度、有效降雨强度对临界曲线的影响.结果表明:饱和度表征降雨强度的计算方法可使土体表面饱和度达到预定值,平均精度为-0.008;有效降雨强度较大时,坡度为50°~60°的边坡,坡度越大产生饱和区的耗时越短,反之耗时越长;坡度30°~40°为易发浅层滑坡的“危险坡度”.

In order to study the critical condition of rainfall-induced saturated-zone forming,the soil saturation based on the MVG model was used to characterize the calculation equations of rainfall intensity.When the surface saturation of the soil reaches above 0.9 for the first time,the saturation is continuously stable at 0.9±0.005 as the critical criterion of the saturated-zone.The numerical calculation method was used to obtain the critical rainfall intensity and rainfall time in the saturated-zone of the soil column and slope.Through the data fitting,a rainfall intensity-time critical curve model of the saturated zone was constructed,and the influence of different slope and effective rainfall intensity on the critical curve was analyzed.The results showed that the calculation method of saturation characterizing rainfall intensity can make the soil surface saturation reach a predetermined value,with an average accuracy of-0.008.When the effective rainfall intensity is large,the greater the slope,the shorter the time consuming to produce the saturated zone for the slope of 50°~60°,on the contrary,the longer it takes.A slope of 30°~40°is a“dangerous slope”prone to shallow landslides.