ORIENTATION OF AGGREGATES OF FINE-GRAINED SOIL - QUANTIFICATION AND APPLICATION

The orientation of aggregates in fine-grained soil is an important fac tor that influences the anisotropy and the engineering property of the fine-grained soil. This paper reviews the basic principle and functio ns of the computer image processing system for soil fabric, and propos es two new quantitative indices to assess the orientation of aggregate s of fine-grained soil, which include alignment entropy (H-m) and freq uency distribution function of clay aggregate orientation Q(alpha). Th e significance of H-m and its differences with anisotropy index (I-a) are discussed. Q(alpha) enables the orientation of the aggregates to b e continuously represented from 0 to 180 degrees and is also taken as a quantitative parameter reflecting the anisotropy of the fine-grained soil in the microstructural mechanical model. The latter sections in this paper give two examples showing the applications of these indices . The first example appraises the changes of fabrics of fine-grained s oil during the process of compacting. The examination results confirm the phenomenon that the deformation of the soil samples during the pro cess of compacting is mainly due to the re-alignment and deformation o f clay aggregates rather than clay platelets; the other example repres ents the application of the Q(alpha) in fitting the creep of anisotrop ic fine-grained soil by the micromechanics model. The fitting results indicate that it is proper to take f(n)=Q(alpha). (C) 1998 Elsevier Sc ience B.V. All rights reserved.