Prediction of permeability of clay by modified Kozeny-Carman equation
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摘要: Kozeny-Carman方程具有明确的物理意义被广泛用于粗粒土渗透系数的计算。为了提高其预估黏土渗透系数的准确度,首先建立等径球形颗粒理论模型,量化结合水占据总孔隙的份额,计算结果表明黏土颗粒间的孔隙几乎都被结合水占据,渗透性受到了极大的影响。然后利用界限含水率与结合水含量的关系,得到了黏土液限含水率推求有效孔隙比的计算公式,对常用的Kozeny-Carman方程进行修正。最后借助热失重试验测算出合肥黏土中结合水质量占液限的比例系数α0选取合肥原状黏土的相关物理参数,分别代入未修正和修正后的Kozeny-Carman方程中,将得到的渗透系数计算值与室内试验的实测值进行对比,发现经修正的Kozeny-Carman方程能较为准确地预估黏土渗透系数,具有一定的实用性。
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关键词:
- 饱和黏土 /
- 等径球形颗粒理论模型 /
- 有效孔隙比 /
- 界限含水率 /
- 热重分析试验 /
- Kozeny-Carman方程
Abstract: The Kozeny-Carman equation has definite physical meaning, and can be widely used in calculating the permeability coefficient of sand.In order to improve the accuracy of using the conventional Kozeny-Carman equation to predict the permeability coefficient for saturated clay, firstly, the theoretical model for equal spherical particle is established, quantifying the share of absorbed water film occupied total pore space, so the permeability is greatly affected.According to the relationship between Atterberg limits and content of absorbed water film, the formula for calculating the efficient void ratio is derivated by the liquid limit.Then, the conventional Kozeny-Carman equation is modified.Finally, the proportion coefficient of absorbed water quality to liquid limit in Hefei clay is calculated by thermal gravimetric tests.Substituting the relevant physical parameters of Hefei clay into the unmodified and modified Kozeny-Carman equation, by comparing the calculated permeability coefficient with the measured value of laboratory tests, the results show that the modified Kozeny-Carman equation can be more accurate for estimating the permeability coefficient of clay. -
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表 1 热重分析结果
Table 1 Results of thermal gravimetric tests
试样编号 自由水失重区间/℃ 自由水/% 弱结合水失重区间/℃ 弱结合水/% 强结合水失重区间/℃ 强结合水/% HF-8 RT~55.59 3.08 55.59~115.59 18.83 115.59~248.59 2.46 HF-23 RT~58.45 3.97 58.45~105.24 24.70 105.24~249.57 3.23 
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表 2 合肥黏土的土工指标
Table 2 Properties of Hefei clay
试样编号 相对质量密度GS 液限wL/% 天然孔隙比e 渗透系数k/(10-8 cm·s-1) HF-4 2.64 38.7 0.884 1.13 HF-6 2.69 35.9 0.964 1.55 HF-8 2.68 32.2 0.996 9.35 HF-9 2.55 42.0 0.981 5.72 HF-11 2.66 35.6 0.915 5.37 HF-14 2.52 41.9 0.933 1.95 HF-23 2.50 50.3 0.962 0.885
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表 3 合肥黏土渗透系数计算结果
Table 3 Calculated results of permeability coefficient of Hefei clay
试样编号 有效孔隙比eu 未修正渗透系数/(10-6) 修正渗透系数/(10-9) 实测渗透系数/(10-8) HF-4 0.141 1.27 8.480 1.130 HF-6 0.261 1.28 39.800 1.550 HF-8 0.368 1.72 127.00 9.350 HF-9 0.202 1.65 23.800 5.720 HF-11 0.226 1.39 32.700 5.370 HF-14 0.165 1.46 13.400 1.950 HF-23 0.047 1.28 0.282 0.885
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