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

土壤容重随田间自然过程和人工过程的变化而变化。土壤容重Rho_b越大，进气吸力h_e越大，导水率K_S越小。虽然基于泊松定律的Kozeny-Carman方程和Miller和Miller(1956)基于相似介质概念的Campbell方法都能从理论上预测导水率与容重的关系，但它们的适用性和局限性一直很模糊。提出了一种非相似介质概念模型，该模型由固相S的特征长度、孔隙相d的特征长度和固相的形状因子tau组成，用于预测给定土壤的He和Ks值作为其Rho_b的函数。通过与Campbell方法和Kozeny-Carman方程的比较，实验表明，非相似介质概念模型不仅适用于分散土，也适用于团粒土，对砂土具有较高的适用性。该模型对聚集废物的适用性取决于适当的形状因子的结果。接近但略大于Rho_b/Rho_S的tau^&lt；**&gt；值可能会给出一个粗略的估计，但强烈建议使用h_e-rho_b关系来确定可靠的tau^&lt；**&gt；值。NSMC模型是一个新的、不断发展的模型。结果表明，机械压实粘性土K_S作为Rho_b函数的预测性较差。通过将形状因子定义为体积密度或压实能的函数，可以改进这类压实土的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.