浑水膜孔灌自由入渗特性试验研究

Experimental study on free infiltration characteristics of muddy water film hole irrigation

通过室内相同条件下清水膜孔灌自由入渗和4种不同含沙率的浑水膜孔灌自由入渗试验,研究了不同含沙率对浑水膜孔灌自由入渗特性和灌水结束后湿润体内水分分布情况的影响,建立了浑水膜孔灌自由入渗参数、湿润锋运移参数和灌水结束后湿润体内水分分布曲线参数与不同含沙率的关系,提出了不同含沙率的浑水膜孔灌自由入渗单位膜孔面积累积入渗量模型、湿润锋运移模型和灌水结束后湿润体内水分分布曲线模型,以及不同含沙率的浑水膜孔灌自由入渗相对相同条件下清水膜孔灌自由入渗的减渗特性及其影响规律.结果表明:随着浑水含沙率的增大,累积入渗量逐渐减小,且均小于相同条件下的清水累积入渗量,入渗系数K随着含沙率的增大而减小,入渗指数α随着含沙率的增大而增大;在相同入渗时间内,随着浑水含沙率的增大,垂直和水平湿润锋运移距离都逐渐减小;灌水结束后湿润体内垂直方向和水平方向质量含水率均随着距膜孔中心距离的增大而逐渐减小;不同含沙率的浑水膜孔灌自由入渗与相同条件下清水对比具有减渗作用,随着含沙率的增大,减渗率逐渐增大.

The influences of sand content on free infiltration characteristics of muddy water film bole irrigation and water content distribution in wetted soil are studied experimentally. Through indoor free infiltration of clean water film hole irrigation experiments with four different sand contents in muddy water, the relationships between free infiltrations of muddy water film hole infiltration parameters, wetting front transport parameters and wetted soil water content distribution parameters after the irrigation and the different sand contents are established. A cumulative infiltration model per unit film area, wetting front transport model, wetted soil water content distribution model and film infiltration declining feature due to the increasing sand content are put forward. It is demonstrated that with increasing muddy water sand content, the cumulative infiltration decreases and less than that of clean water under the same condition. The infiltration coefficient K decreases with increasing sand content, but the infiltration in- dex c~ increases with the increasing content. In the same infiltration time, with increasing sand content, the vertical and horizontal wetting front transport distances are gradually reduced. With increasing distance from the center of film hole, the water mass content in wetted soil reduces gradually in the vertical and horizontal directions. The sand contents in muddy water can reduce film hole irrigation infiltration in comparison with clean water, particularly, the higher the sand content, the smaller the infiltration rate.