Sampling and Testing in Stiff Crustal Clays

by Kenneth McManis, Univ of New Orleans, New Orleans, LA, USA,
Ara Arman, Univ of New Orleans, New Orleans, LA, USA,

Document Type: Proceeding Paper

Part of: Geotechnical Aspects of Stiff and Hard Clays


In desiccated clays, the secondary structure consisting of fissures and slickensides greatly influence the measurement of soil strength. In a sampling study, such soils were found to be common and yielded much scatter in conventional laboratory test results. However, the shear strength measured with the smaller tube samples were generally greater than those from the larger tubes. This was attributed to two factors: the combination of sample size versus frequency of cracks; and the remolding and smearing effects on the fissures during sampling. The remolded shear strength often approached or exceeded the undisturbed strength regardless of the sample size. Extended storage time of the samples was also found to be more detrimental to the stiff fissured clays producing a further reduction in strength. X-ray radiography was used in evaluating the quality and uniformity of samples.

Subject Headings: Soil strength | Cracking | Laboratory tests | Soil tests | Clays | Shear strength | Soil structures | Structural strength

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