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The topology of pore structure in cracking clay soil I. The estimation of numerical density

1988; Wiley; Volume: 39; Issue: 3 Linguagem: Inglês

10.1111/j.1365-2389.1988.tb01217.x

2056-5240

G. J. T. Scott, R. Webster, Stephen Nortcliff,

Geochemistry and Geologic Mapping

SUMMARY The numerical density, N v , of the pore structure of soil is the number of disjoint networks of pores per unit volume of soil. A method is described for estimating N v of patterns of cracks that dominate in many clay subsoils. The cracks are photographed from numerous close‐spaced parallel sections and skeletonized; by comparing the skeletonized photographs sequentially, individual networks are tracked from one section to another and counted. The average number of networks that appears or disappears per section in the sequence is a measure of the numerical density and is obtained by regressing the counts on the volume of soil spanned by the sections. The regressions for appearances and disappearances converge on one another and stabilize within 10 to 20 sections, so that N v can be estimated for a sample of soil with moderate effort. Estimates of N v for cracks wider than 60 μm in subsoil of the Windsor series, sampled at two nearby sites and 5 years apart in time and determined from sections at 50 μm intervals, were approximately 32 cm −3 and 36cm −3 . That of N v in the Swanwick series subsoil nearby was about 75 cm −3 .