Measuring and modelling the soil shrinkage characteristic curve
Measuring and modelling the soil shrinkage characteristic curve
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DOI：
10.1016/j.geoderma.2006.08.022
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发表时间：
2006-12
期刊：
影响因子：
6.1
通讯作者：
W. Cornelis;J. Corluy;H. Medina;J. Diaz;R. Hartmann;M. Meirvenne;M. Ruiz
中科院分区：
文献类型：
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作者：
W. Cornelis;J. Corluy;H. Medina;J. Diaz;R. Hartmann;M. Meirvenne;M. Ruiz
膨胀和收缩土壤的大孔隙率以及较小程度的微孔隙率受到其收缩行为的影响。体积随含水量变化而变化的幅度通常用土壤收缩特性曲线（SSCC）来描述，即空隙率与含水率之间的关系。目前，已经描述了许多用于测定 SSCC 的技术。我们分别对古巴哈瓦那省甘蔗下变性土和立克西土七个层位中采集的原状土样、扰动土样和土块应用了岩心法、橡皮球法和石蜡涂覆法。我们证明球囊和石蜡涂层方法显示出相似的结果，而核心方法产生的收缩不太明显。后者是由于各向异性收缩造成的，这一点通过几何因子随含水率的变化而得到证实，在收集未受干扰的土芯时颗粒可能会重新定向，以及在干燥时出现小裂缝。我们进一步表明，核心方法产生了更高的散射，这是由更高的测量误差和样品干燥时破碎造成的。由于其优越的性能，随后选择气球方法来测试描述 SSCC 的九种不同参数模型。可以区分在 RMSE、决定系数和 Akaike 信息准则方面表现最好的一组四个模型。这些模型包括 McGarry 和 Malafant 的三个线性方程模型 [McGarry, D., Malafant, K.W.J., 1987。无侧限土壤单位体积变化的分析。土壤科学。苏克。是。 J. 51, 290–297]，Braudeau 等人的线性和指数五方程组合模型。 [Braudeau, E., Costantini, J.M., Bellier, G., Colleuille, H., 1999。土壤收缩曲线测量和表征的新装置和方法。土壤科学。苏克。是。 J. 63, 525–535]，Chertkov 理论三方程模型的修改版本 [Chertkov, V.Y., 2000。模拟土壤粘土基质的孔隙结构和收缩曲线。 Geoderma 95, 215–246] 以及 Groenevelt 和 Grant 的 Logistic 模型的简化版本 [Groenevelt, P.H., Grant, C.D., 2001。重新评估一些英国膨胀土壤的结构特性。欧元。 J.土壤科学。 52, 469–477]。虽然表现非常好，但 McGarry 和 Malafant 模型并没有描述完整的 SSCC，而 Braudeau 等人。模型包含较多的参数。改进后的 Chertkov 模型观察到总体最高性能。然而，修改后的 Groenevelt 和 Grant 模型的优点是最优雅，因为它仅由一个方程组成。
The macroporosity, and to a lesser extent the microporosity, of swelling and shrinking soils is affected by their shrinkage behaviour. The magnitude of the changes in bulk volume in response to changes in water content is usually described by the soil shrinkage characteristic curve (SSCC), i.e. the relation between the void ratio and the moisture ratio. At present, many techniques have been described for determination of the SSCC. We have applied the core method, the rubber-balloon method and the paraffin-coated method on respectively undisturbed soil samples, disturbed soil samples and soil clods collected from seven horizons of a Vertisol and a Lixisol under sugar cane in the Havana province, Cuba. We demonstrated that the balloon and paraffin-coated method showed similar results, whereas the core method produced less pronounced shrinkage. The latter was due to the anisotropic shrinkage as was confirmed by the change of the geometry factor with the moisture ratio, to a possible reorientation of particles when collecting undisturbed soil cores, and to the occurrence of small cracks upon drying. We have further shown that the core method produced much higher scatter, which was explained by higher measuring errors and crumbling of the samples as they dried out. Because of its superior behaviour, the balloon method was then selected to test nine different parametric models that describe the SSCC. A group of four models which performed best in terms of RMSE, coefficient of determination and Akaike Information Criterion could be distinguished. These models include the three linear equations model of McGarry and Malafant [McGarry, D., Malafant, K.W.J., 1987. The analysis of volume change in unconfined units of soil. Soil Sci. Soc. Am. J. 51, 290–297], the combined linear and exponential five equations model of Braudeau et al. [Braudeau, E., Costantini, J.M., Bellier, G., Colleuille, H., 1999. New device and method for soil shrinkage curve measurement and characterization. Soil Sci. Soc. Am. J. 63, 525–535], a modified version of the theoretical three equations model of Chertkov [Chertkov, V.Y., 2000. Modeling the pore structure and shrinkage curve of soil clay matrix. Geoderma 95, 215–246] and a simplified version of the logistic model of Groenevelt and Grant [Groenevelt, P.H., Grant, C.D., 2001. Re-evaluation of the structural properties of some British swelling soils. Eur. J. Soil Sci. 52, 469–477]. Though performing very well, the McGarry and Malafant model does not describe the complete SSCC, whereas the Braudeau et al. model contains a relatively large number of parameters. Overall highest performance was observed for the modified Chertkov model. The modified Groenevelt and Grant model, however, has the advantage of being the most elegant as it consists of only one single equation.