未飽和紅土水力傳導係數之研究

Study on Coefficient Of Permeability in Unsaturated Laterite

郭麗娥(Li-A Kuo)

指導教授 ： 張德鑫

中原大學/工學院/土木工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300444

摘要

摘要
本文主要研究桃園地區紅土之土壤水分特性，首先以本研究所做實驗之土壤含水量與土壤張力關係為依據，並利用曲線擬合技術，決定不同經驗式之土壤水分保持曲線參數，則可得桃園地區紅土之土壤水分保持曲線，並求得未飽和層水力傳導係數與土壤含水量之變化關係。
由於推估未飽和層土壤水力傳導係數與土壤含水量之關係，必須知道土壤之飽和水力傳導係數值。本研究由實驗室之土壤水力傳導實驗得知桃園地區紅土之飽和水力傳導係數值約為2.929 ，其與相關文獻比較此值尚稱合理。
為驗證本研究所得參數之合理性，本研究採用數值模擬降雨對土壤含水量之變化，並與現地實測資料比對。雖有部份差距，但土壤水分含量時間及空間變化趨勢一致，可知本研究所推估之紅土水分保持曲線及非飽和土壤水力傳導係數值與土壤含水量之關係式，尚稱合理，造成差距之原因為模式中並未考慮到土壤顆粒中之毛管效應，造成降雨初期土壤水分含量其實測值與模擬值之偏離，由此可知，降雨初期毛管作用對水流之影響將大於土壤滲流作用。

關鍵字

毛管效應 ； 水力傳導係數 ； 土壤水分保持曲線

並列摘要

In order to obtain soil water characteristic curves of laterite in Tao-Yuan, and gain the variation relation between unsaturated hydraulic conductivity and soil water content. First of all, this study the water characteristic curves were determined by measured soil water content and soil suction. Then, the parameters of characteristic curves for different formula are obtained by curve fitting techniques.
If someone want to estimate the relation between unsaturated hydraulic conductivity and soil water content, he must have saturated hydraulic conductivity in advance. In this research the measured coefficient of saturated hydraulic conductivity is 2.929 cm/hr, which is reasonable with the measured site data.
To verify the reason of fitted parameters, in this study, the variation of soil water content due to ran-fall is investigated by numerical simulation. The simulated results are compared with the measured site data. Even though there is small discrepancy between each other, but the space and time distributions of soil water content show the same trend. The reason for causing the discrepancy is probably due to the neglect of capillary effect of soil particles. Since the capillary effect will cause significant difference of soil water content.

並列關鍵字

hydraulic conductivity ； soil water characteristic curves

參考文獻

9. 張德鑫、蔡西銘、鄭正隆、李昆性、郭麗娥，（2002），「降雨滲流現象對邊坡穩定之時變分析」，行政院農委會水土保持局科技計畫，坡地災害警戒值訂定與土石流觀測示範站之研究。

12. Archer, J.R., and Smith, P.D. (1972), “The Rrlation Between Bulk Density Available Water Capacity,and Air Capacity of Soil,’’ J. Soil Sci. Vol.23, p.475-480.

16. Burdine, N.T. (1953), “Relative Permeability Calculations from Pore – Size Distribution Data,’ Trans. Am. Inst. Min. Metall. Pet. Eng., 198, p.71-77.

17. Bouyoucos, G. J. and Mick, A.H. (1940), “An Electrical Resistance Method for the Continuous Measurement of Moisture under Frield Conditions,’ Michigan State College Tech. Bull.

18. Campbell, G. (1974), “A Simple Method for Determining Unsaturated Conductivity from Moisture Retention Data.’’ Soil Sci. Vol.117, No.6, p.311-314.