Consolidation of Loess, 1971

(1971) Consolidation of Loess, 1971. Transportation, Department of


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Effective stress paths for a loessial soil subject to collapse during confined compression have been determined from the results of a testing program consisting of (1) confined compression tests on natural samples of loess with initial water contents ranging from air-dry to saturation, (2) negative pore-water pressure measurements to -300 psi during these tests, and (3) Ko-tests in which the lateral stress ratio was measured for one-dimensional strain. Before collapse, Ko was found to average 0.23, an extremely low value for a loose soil, whereas after collapse, Ko increased to 0.54, which is consistent with values for other soils. Because of the low Ko-values before collapse, the effective stress path for loading in confined compression initially approaches the failure envelope. At collapse the stress path intersects the failure envelope and thereafter it changes direction as a consequence of the higher Ko-value after collapse. From the stress path interpretation of the results, it is demonstrated that the collapse mechanism of loess in confined compression and during wetting is a shear phenomenon and subject of analysis in terms of effective stresses.

Item Type: Departmental Report
Keywords: Collapse properties, Compression tests, Loess, Pore water pressures, Stress ratio, Soils
Subjects: Transportation
Transportation > Materials
Transportation > Research
Transportation > Environment
ID Code: 22514
Deposited By: Iowa DOT Library
Deposited On: 26 Jul 2016 12:35
Last Modified: 26 Jul 2016 12:35