不同容重条件下深层坑渗灌土壤水分运动的数值模拟

Study on numerical simulation of soil water movement under the condition of deep pit infiltration irrigation with different soil bulk densities

【目的】探究不同土壤容重条件下深层坑渗灌土壤水分的运动规律。【方法】以非饱和土壤水分运动方程为基础,建立深层坑渗灌的数值模拟模型,采用Galerkin有限单元法进行数值求解,用5种不同土壤容重的试验资料对模拟结果进行验证。【结果】容重不同的5种土壤在不同时刻湿润锋的模型值均略小于实测值;非边界上土壤含水量模型值的相对误差为1.98%,边界上土壤含水量模型值的相对误差为10.97%,且上边界的模型值普遍偏小,下边界的计算值普遍偏大;基于研究资料建立了土壤含水量的上、下边界修正方程。【结论】该模型结合修正方程,可以作为一种预测深层坑渗灌条件下土壤水分运动及其含水量分布的有效方法。

【Objective】 Based on non-saturated soil water movement equation,the numerical simulation model of deep pit infiltrating irrigation was established to understand its law of soil water movement.【Method】 The model was solved with Galerkin finite element method and verified by the laboratory experiments with 5 soil bulk densities.【Result】 The results showed that the calculation wetting front value was a little smaller than measurement;the overall relative error of the calculated water content was 1.98% at non-boundary,whereas 10.97% at boundary,and the calculated values of soil water content was generally smaller at up boundary,while generally larger at blew boundary.The model can be effective in simulating the process of wetting front and water content distribution of deep pit infiltrating irrigation.The modified equation at up and down boundary was established.【Conclusion】 Compared with the modified equation,the model may be an effective way to predict the process of and water content distribution under deep pit infiltration irrigation.