基于统计模型的非饱和土渗透系数函数研究
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摘要
对比分析2种基于统计模型预测非饱和土渗透系数的方法(Kunze法与Fredlund法),得出:2种方法本质相同,仅选取的积分限和积分变量形式不同,是对同一问题的2种不同表述。对其简化计算方法中各参数的选取进行深入分析,结果表明:分段数m取值介于15~50时较为合理,且Fredlund方法中取ln(1 000 000)(假定残余含水率为0)为积分上限、进气值的对数为积分下限,理论上会使预测结果偏大。当接近饱和含水率时,非饱和渗透系数随含水率的变化较为敏感,当接近残余含水率时,渗透系数变化率很小且差异性趋于不明显。
By comparing and analyzing two methods( Kunze's method and Fredlund's method) based on statistical models to predicting the hydraulic conductivity of unsaturated soils,we found that they are exactly the same in essence just with different limits of integration and integration variable forms. Moreover,by analyzing the selection of parameters in their simplified calculation we obtain that it is more reasonable to determine the value of m within15- 50. Theoretically the prediction result will be larger if ln( 1000000)( residual water content is assumed to be0) is taken as the integration upper limit and logarithm of air-entry value as the integration lower limit in Fredlund method.
By comparing and analyzing two methods( Kunze's method and Fredlund's method) based on statistical models to predicting the hydraulic conductivity of unsaturated soils,we found that they are exactly the same in essence just with different limits of integration and integration variable forms. Moreover,by analyzing the selection of parameters in their simplified calculation we obtain that it is more reasonable to determine the value of m within15- 50. Theoretically the prediction result will be larger if ln( 1000000)( residual water content is assumed to be0) is taken as the integration upper limit and logarithm of air-entry value as the integration lower limit in Fredlund method.
引文
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[2]FREDLUND D G,XING A,HUANG S.Predicting the Permeability Function for Unsaturated Soils Using the Soilwater Characteristic Curve[J].Canadian Geotechnical Journal,1994,31(4):533-546.
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[7]梁燕,邢鲜丽,李同录,等.晚更新世黄土渗透性的各向异性及其机制研究[J].岩土力学,2012,33(5):1313-1318.(LIANG Yan,XING Xian-li,LI Tong-lu,et al.Study of the Anisotropic Permeability and Mechanism of Q3 Loess[J].Rock and Soil Mechanics,2012,33(5):1313-1318.(in Chinese))
[8]常波,吴益平,何高峰,等.临江Ⅱ号崩滑体土水特征曲线试验研究[J].长江科学院院报,2012,29(9):53-58.(CHANG Bo,WU Yi-ping,HE Gao-feng,et al.Tests for Soil-Water Characteristic Curve of Riverside Slump-mass[J].Journal of Yangtze River Scientific Research Institute,2012,29(9):53-58.(in Chinese))
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[11]CRONEY D,COLEMAN J D.Pore Pressure and Suction in Soil[C]∥Proceedings of Conference on Pore Pressure and Suction in Soils.Institution of Civil Engineers.Butterworths,London,March 30-31,1960:31-37.
[12]RICHARDS L A.Physical Condition of Water in Soil[M]∥Methods of Soil Analysis.Part 1.Physical and Mineralogical Properties,Including Statistics of Measurement and Sampling.Madison:American Society of Agronomy,1965:128-152.
[13]FREDLUND D G,XING A.Equations for the Soil-water Characteristic Curve[J].Canadian Geotechnical Journal,1994,31(4):521-532.
[14]FREDLUND D G,RAHARDJO H.Soil Mechanics for Unsaturated Soils[M].New York:John Wiley&Sons,1993:256-278.
[2]FREDLUND D G,XING A,HUANG S.Predicting the Permeability Function for Unsaturated Soils Using the Soilwater Characteristic Curve[J].Canadian Geotechnical Journal,1994,31(4):533-546.
[3]叶为民,钱丽鑫,白云,等.由土-水特征曲线预测上海非饱和软土渗透系数[J].岩土工程学报,2005,27(11):1262-1265.(YE Wei-min,QIAN Li-xin,BAI Yun,et al.Predicting Coefficient of Permeability from Soil-water Characteristic Curve for Shanghai Soft Soil[J].Chinese Journal of Geotechnical Engineering,2005,27(11):1262-1265.(in Chinese))
[4]张锐,郑健龙,杨和平.宁明膨胀土渗透特性试验研究[J].桂林工学院学报,2008,28(1):48-53.(ZHANG Rui,ZHENG Jian-long,YANG He-ping.Permeability Test of Ningming Expansive Soil[J].Journal of Guilin University of Technology,2008,28(1):48-53.(in Chinese))
[5]张红芬,李永乐,刘翠然,等.非饱和土渗透系数直接试验法和间接计算法[J].人民黄河,2011,33(4):139-141.(ZHANG Hong-fen,LI Yong-le,LIU Cui-ran,et al.Method of Direct Test and Method of Indirect Calculation of Percolation Coefficient of Unsaturated Soil[J].Yangtze River,2011,33(4):139-141.(in Chinese))
[6]李小伟,王世梅,黄净萍.密度对非饱和粘土渗透系数的影响研究[J].西北地震学报,2011,33(B08):214-217.(LI Xiao-wei,WANG Shi-mei,HUANG Jing-ping.Influence of Density on Permeability Coefficient of Unsaturated Soil[J].Northwestern Seismological Journal,2011,33(B08):214-217.(in Chinese))
[7]梁燕,邢鲜丽,李同录,等.晚更新世黄土渗透性的各向异性及其机制研究[J].岩土力学,2012,33(5):1313-1318.(LIANG Yan,XING Xian-li,LI Tong-lu,et al.Study of the Anisotropic Permeability and Mechanism of Q3 Loess[J].Rock and Soil Mechanics,2012,33(5):1313-1318.(in Chinese))
[8]常波,吴益平,何高峰,等.临江Ⅱ号崩滑体土水特征曲线试验研究[J].长江科学院院报,2012,29(9):53-58.(CHANG Bo,WU Yi-ping,HE Gao-feng,et al.Tests for Soil-Water Characteristic Curve of Riverside Slump-mass[J].Journal of Yangtze River Scientific Research Institute,2012,29(9):53-58.(in Chinese))
[9]CHILDS E C,COLLIS-GEORGE N.The Permeability of Porous Materials[J].Proceedings of the Royal Society of London.Series A.Mathematical and Physical Sciences,1950,201(1066):392-405.
[10]MARSHALL T J.A Relation between Permeability and Size Distribution of Pores[J].Journal of Soil Science,1958,9(1):1-8.
[11]CRONEY D,COLEMAN J D.Pore Pressure and Suction in Soil[C]∥Proceedings of Conference on Pore Pressure and Suction in Soils.Institution of Civil Engineers.Butterworths,London,March 30-31,1960:31-37.
[12]RICHARDS L A.Physical Condition of Water in Soil[M]∥Methods of Soil Analysis.Part 1.Physical and Mineralogical Properties,Including Statistics of Measurement and Sampling.Madison:American Society of Agronomy,1965:128-152.
[13]FREDLUND D G,XING A.Equations for the Soil-water Characteristic Curve[J].Canadian Geotechnical Journal,1994,31(4):521-532.
[14]FREDLUND D G,RAHARDJO H.Soil Mechanics for Unsaturated Soils[M].New York:John Wiley&Sons,1993:256-278.
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