强降雨条件下含大孔隙土柱水分非平衡运移特性

发布时间：2018-06-25 00:57

  本文选题：强降雨 + 大孔隙　； 参考：《同济大学学报(自然科学版)》2017年04期

【摘要】：为揭示强降雨条件下大孔隙土柱水分非平衡运移特性,基于双重渗透模型与运动波模型,采用有限差分技术编制计算程序,对降雨强度、持时、初始含水率、两域间等效扩散距离、经验参数(rw,n*)等对水分非平衡迁移特性进行分析.结果表明,双重渗透模型计算所得的水分交换峰值比运动波模型计算值大但水分交换深度范围小.双重渗透模型模拟表层水分变化较好,而运动波模型模拟土层下部水分变化较好.两种计算模型得到的体积含水率沿深度范围内呈现双拐点特性.湿润峰深度、水分交换深度范围均随降雨强度、降雨持时的增大呈现变大趋势.随着初始含水率逐渐接近饱和含水率,湿润峰位置下移,水分交换深度范围变大,但峰值骤降.随着两域间等效扩散距离增大,水分交换速率大幅减小,造成比较明显的非平衡流现象;但当两域间等效扩散距离超过5cm时,湿润峰位置、水分交换速率、基质域剖面含水率相差很小.随着经验参数值rw,n*的增大,湿润峰下降速度变慢,但水流交换速度增大.当rw大于0.4或n*大于2.5,湿润峰下降速度、土壤剖面含水率、水流交换速度与范围变化幅度明显降低,产生非平衡流的几率降低.
[Abstract]:In order to reveal the non-equilibrium migration characteristics of water in macroporous soil column under heavy rainfall, based on double permeability model and motion wave model, the calculation program is compiled by using finite difference technique, and the initial moisture content is calculated when rainfall intensity is sustained. The equivalent diffusion distance between the two domains and empirical parameters (rwn*) are used to analyze the characteristics of water non-equilibrium migration. The results show that the water exchange peak value calculated by the double permeation model is larger than that by the moving wave model, but the water exchange depth range is smaller than that calculated by the moving wave model. The double permeation model simulates the surface moisture change better, while the moving wave model simulates the lower soil moisture change better. The volume water content obtained by the two models shows double inflection points in the range of depth. The range of wetting peak depth and water exchange depth all increased with rainfall intensity, and the increase of rainfall duration showed a trend of increasing. With the initial moisture content approaching the saturated water content, the position of the wetting peak moves down, and the range of water exchange depth becomes larger, but the peak value drops sharply. With the increase of the equivalent diffusion distance between the two domains, the water exchange rate decreases significantly, resulting in a more obvious phenomenon of non-equilibrium flow, but when the equivalent diffusion distance between the two domains exceeds 5cm, the moisture exchange rate and the wetting peak position are obtained. The difference of moisture content in substrate profile is very small. With the increase of the empirical parameter value rwn *, the decrease rate of wetting peak becomes slower, but the velocity of water exchange increases. When r w > 0.4 or n * > 2.5, the moisture content of soil profile, water exchange velocity and range decrease obviously, and the probability of non-equilibrium flow decreases.
【作者单位】： 福州大学土木工程学院;福州大学数学与计算机科学学院;
【基金】：国家自然科学基金(41302215) 福建省自然科学基金(2014J01185)
【分类号】：TU43
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本文编号：2063771