Published: Jan 1955
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In principle, determination of the permeability of soils is quite simple. However, due to natural variations of material in place, it is often difficult to relate tests on small samples to larger masses. In sampling soils it is hard to prevent disturbing the moisture or density or particularly the structure of the soil. Changes in the air or chemical or organic content of the permeating fluid can cause large differences. Migration of particles may occur both in the field and laboratory. While some variables can be arbitrarily controlled or eliminated in the laboratory, it is often necessary to consider them in field applications. The Symposium includes papers discussing the importance, evaluation, and control of most of these factors. Field permeability tests are compared, described, and evaluated by formulas. Correlations are presented between permeability and density and gradation of granular materials. A new sampler and a device for testing under small gradients are described. The importance of relating tests to field conditions is stressed. The test value is expressed as length divided by time in a variety of units, but it is generally called coefficient of permeability, although hydraulic conductivity is suggested as being more consistent with other fields such as electrical and thermal conductivity. While the variety of field situations seems to preclude a single standard test method, it should be possible to increase the consistency of results by recommendation of preferred practices.
Barber, Edward S.
Civil Engineerchairman of Subcommittee R-4 of Committee D-18 on Soils for Engineering Purposes, Arlington, Va.