改进的Green-Ampt模型及其试验验证

AN IMPROVED GREEN-AMPT MODEL AND ITS EXPERIMENTAL VERIFICATION

鉴于Green-Ampt模型过于简化、难以反映实际入渗特征,且其假设与实际入渗规律不符,本文为了弥补Green-Ampt模型的不足,提出了一种改进的Green-Ampt模型。提出的模型考虑了含水率与土体深度的关系,将土壤剖面划分为饱和区、过渡区以及天然区,土柱试验验证了所提出模型的准确性,也证实了入渗过程中过渡区的存在。试验结果表明:Green-Ampt模型计算值明显偏离实际累计入渗量,提出的模型总体上更接近实际累计入渗量。将该模型用于非饱和斜坡稳定性分析,计算结果揭示了Green-Ampt模型低估了斜坡的稳定性系数。提出的改进Green-Ampt模型为分析降雨滑坡风险提供参考。

Because Green-Ampt model is too simplified to accurately calculate the total infiltration volume,we propose an improved Green-Ampt model which conforms to the actual infiltration law in this paper.The proposed model divides the soil profile into saturated,transitional saturated and natural saturated zones.A soil column test is performed to verify the accuracy of the proposed model and the existence of transitional zone.Three indexes are used to evaluate the accuracy of the model.They are the mean absolute error(MAE),the mean absolute relative error(MARE)and the root mean square error(RMSE).The MAE,MARE and RMSE are smaller than those of the classical Green-Ampt model.As a result,the accuracy of the proposed model is higher than that of Green-Ampt model.The proposed model is also used to analyze the stability of an unsaturated soil slope.The calculated results show that the slope angle and precipitation rainfall intensity are inversely proportional to the slope safety factor,and the former has a greater influence impact on the slope safety factor.Compared with the proposed model,the Green-Ampt model underestimates the slope safety.The improved Green-Ampt model provides references for analyzing the risk of rainfall and landslides.