本文選題：強降雨 + 大孔隙�。� 參考：《同濟大學(xué)學(xué)報(自然科學(xué)版)》2017年04期

【摘要】：為揭示強降雨條件下大孔隙土柱水分非平衡運移特性,基于雙重滲透模型與運動波模型,采用有限差分技術(shù)編制計算程序,對降雨強度、持時、初始含水率、兩域間等效擴散距離、經(jīng)驗參數(shù)(rw,n*)等對水分非平衡遷移特性進行分析.結(jié)果表明,雙重滲透模型計算所得的水分交換峰值比運動波模型計算值大但水分交換深度范圍小.雙重滲透模型模擬表層水分變化較好,而運動波模型模擬土層下部水分變化較好.兩種計算模型得到的體積含水率沿深度范圍內(nèi)呈現(xiàn)雙拐點特性.濕潤峰深度、水分交換深度范圍均隨降雨強度、降雨持時的增大呈現(xiàn)變大趨勢.隨著初始含水率逐漸接近飽和含水率,濕潤峰位置下移,水分交換深度范圍變大,但峰值驟降.隨著兩域間等效擴散距離增大,水分交換速率大幅減小,造成比較明顯的非平衡流現(xiàn)象;但當(dāng)兩域間等效擴散距離超過5cm時,濕潤峰位置、水分交換速率、基質(zhì)域剖面含水率相差很小.隨著經(jīng)驗參數(shù)值rw,n*的增大,濕潤峰下降速度變慢,但水流交換速度增大.當(dāng)rw大于0.4或n*大于2.5,濕潤峰下降速度、土壤剖面含水率、水流交換速度與范圍變化幅度明顯降低,產(chǎn)生非平衡流的幾率降低.
[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.
【作者單位】： 福州大學(xué)土木工程學(xué)院;福州大學(xué)數(shù)學(xué)與計算機科學(xué)學(xué)院;
【基金】：國家自然科學(xué)基金(41302215) 福建省自然科學(xué)基金(2014J01185)
【分類號】：TU43
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本文編號：2063771