Scaling of Physical Properties of Soils by Using Non-Similar Media Concept

土壤的容重随着田间自然和人工过程的变化而变化。土壤容重RHO_B越大，空气进入吸力h_e越大，导水率K_s越小。尽管基于Poiffille定律的Kozeny-Carman方程和基于米勒和米勒（1956）的类似介质概念（SMC）的坎贝尔方法都能够从理论上预测水力传导率的体积密度依赖性，但它们的适用性和局限性一直是模糊的。本文提出了一个由固相特征长度S、孔隙相特征长度d和固相形状因子τ组成的非相似介质概念（NSMC）模型，用于预测给定土壤的he和Ks值随rho_B的变化。通过与坎贝尔法和Kozeny-Carman方程的比较，表明NSMC模型不仅适用于团聚体土，也适用于分散体土，对桑迪的he（rho_B）和Ks（rho_B）的预测也具有很高的适用性。该模型对聚集的织物的适用性取决于适当的形状因子τ ^<**>的发现。τ ^<**>值接近但略大于rho_B/rho_s可以给出一个粗略的估计，但强烈建议测量h_e-rho_B关系，通过它来确定可靠的τ ^<**>值。结果表明，NSMC模型对机械压实粘性土的K_s与ρ_B的函数关系的预测性较差。通过将形状因子定义为体积密度或压实能的函数，可以改进这种压实土的NSMC模型。

The bulk density of a soil changes with natural and artificial processes in a field. The larger the bulk density RHO_b of the soil, the larger the air entry suction h_e and the smaller the hydraulic conductivity K_s. Although both the Kozeny-Carman equation, based on Poiseuille's law, and Campbell's method, based on a similar media concept (SMC) by Miller and Miller (1956), are able to predict bulk density dependencies of hydraulic conductivities theoretically, the applicabilities and limitations of them have been vague. This study proposed a non-similar media concept (NSMC) model, composed of a characteristic length for the solid phase S,that for the pore phase d and a shape factor tau of the solid phase, to predict he and Ks values of a given soil as functions of its rho_b. By comparing the NSMC model with the Campbell method and the Kozeny-Carman equation, it was clarified experimentally that the NSMC model is applicable to aggregated soils in the predictions of he (rho_b) and Ks (rho_b) as well as to dispersed soils.The applicability of NSMC model to sandy soil was sufficiently high. The applicability of this model to an aggregated woil depended upon the findings of an adequate shape factor tau^<**>. The tau^<**> value close to but a little larger tha rho_b/rho_s may give a rough estimation, but it is strongly recommended to measure the h_e-rho_b relation by which a reliable tau^<**> value is determined.The NSMC model is a new and growing model. It was shown that the predictability of K_s as functions of rho_b of mechanically compacted clayy soils by the NSMC model were relatively poor. The NSMC model for such compacted soils may be improved by defining the shape factor as a function of the bulk density or compaction energy.