恒定水头井入渗Green-Ampt模型的改进与验证

Improvement and verification of the Green-Ampt model for constant-head well permeameter

在假定恒定水头井入渗近似为以井内积水表面积为入渗面的一维入渗基础上,用湿润体内平均体积含水率增量代替Green-Ampt活塞模型中的饱和含水率与初始含水率差值。用入渗率和累积入渗量倒数的线性关系间接推求Green-Ampt模型中的参数,用湿润锋平均基质吸力和土壤饱和导水率。从而建立了适用于恒定水头井入渗的Green-Ampt模型。同时根据体积等效原理,定义了三维入渗中难以直接测定的概化湿润锋深度。经3种类型土壤的室内试验检验,表明该模型具有较好的精度,能精确地计算不同累积入渗量时的湿润体体积。

Based on the hypothesis that the parameter of three dimensional infiltration in constanthead well is similar to one dimensional infiltration,an improved Green-Ampt model,in which the ponded surface is adopted as the infiltration surfarce,is proposed.The increment of the average volumetric water content is used as the substitution for D-value between saturated water content and initial water content,and the linear relationship between infiltration rate and the reciprocal of cumulative infiltration water amount is used to calculate the average matric potential suction of the wetting front and general saturated hydraulic conductivity.In the meantime,the general wetting depth,which was difficult to measure directly in three dimensional infiltrations,was defined according to the volumetric equivalent principle.The precision of the model is verified by laboratory tests with three types of soil.This model can be used to calculate the soil wetted volume accurately according to the cumulative infiltration water amount.