摘要
天然土质边坡在地质和人为因素的作用下,通常呈现一定层状结构,在强降雨作用下会产生入渗和坡面径流。研究降雨条件下坡面径流与地表入渗相互影响过程,对山地洪水和滑坡灾害防治具有重要意义,为了研究层状土边坡地表与地下渗流的相互作用机制,针对上粗下细型层状土边坡降雨入渗忽略坡面径流影响导致入渗分析不符合实际这一问题,基于Moore双层入渗和坡面径流控制方程建立耦合模型,并通过Python编制相应的计算程序分析耦合条件下双层结构边坡降雨产流及停雨后雨水重分布全过程。数值分析结果表明:边坡土体降雨入渗过程与坡面径流深度有关;降雨初期降雨强度<坡面入渗能力,入渗速率等于降雨强度,坡面产流后入渗速率随降雨持时逐渐减小趋于稳定;当湿润锋跨过土层交界面时,入渗速率急剧减小,最终等于次层土的渗透率,表明上粗下细型层状土入渗速率主要由次层土控制,同时降雨停止后径流快速衰退,已入渗的雨水在重力和湿润锋下方土体基质吸力的作用下继续向下推移,湿润锋入渗深度随雨水重分布历时趋于平缓。算例表明,该计算模型与计算方法可行,能够较好地反映实际层状土边坡的降雨入渗过程,为类似的层状土边坡研究提供计算依据。
Natural soil slopes often consist in two or more soil layers due to the geological and human factors.Under heavy rainfall,rainwater infiltrates into the slope,and when the rainfall intensity is greater than the infiltration rate of the soil,the runoff occurs very shortly on the slope surface.Understanding the interaction process of slope runoff and surface infiltration under rainfall conditions is critical for flash flood and landslide risk management.However,the mechanism of the interaction between surface and underground seepage of layered soil slopes has so far remained poorly understood.The studies of rainfall infiltration into the two-layered slope with coarse-over-fine stratification usually ignore the influence of slope runoff resulting in an unrealistic infiltration analysis.A coupled model was established to analyze the rainfall runoff and the rainwater redistribution process after rainfall,and the corresponding calculation program was compiled by Python to solve this problem based on the Moore two-layer infiltration and slope runoff governing equations.The numerical analysis results showed that the rainfall infiltration process of the slope soil was related to the runoff depth on the slope surface.When rainfall intensity was smaller than hydraulic conductivity of surface soil,initial infiltration rate was equal to rainfall intensity,and gradually decreased with the rainfall duration after the runoff on the slope,and finally tended to be stable.The infiltration rate dramatically dropped and eventually equaled the permeability of the subsoil when the wetting front crossed the interface of the soil layers.It indicated that the infiltration rate of the slope with coarse-over-fine stratification was mainly controlled by the lower fine soil layer.The runoff was rapidly degraded after the rainfall stops,and the infiltrated rainwater continued to move downward under the combined action of gravity and the matrix suction of the soil under the wetting front.The runoff was rapidly degraded after the rainfall stops,
作者
韩同春
苏钰钦
张宇
HAN Tongchun;SU Yuqin;ZHANG Yu(Research Center of Coastal and Urban Geotechnical Eng.,Zhejiang Univ.,Hangzhou 3100588,China)
出处
《工程科学与技术》
EI
CAS
CSCD
北大核心
2020年第6期145-152,共8页
Advanced Engineering Sciences
基金
浙江省自然科学基金项目(LY18E080006)。
