Time and Stress-Compressibility Interrelationship

by Gholamreza Mesri, (A.M.ASCE), Assoc. Prof. of Civ. Engrg.; Univ. of Illinois at Urbana-Champaign, Urbana, Ill.,
Paul M. Godlewski, Research Asst.; Dept. of Civ. Engrg., Univ. of Illinois at Urbana-Champaign, Urbana, Ill.,

Serial Information: Journal of the Geotechnical Engineering Division, 1977, Vol. 103, Issue 5, Pg. 417-430

Document Type: Journal Paper


For any natural soil a unique relationship exists between secondary compression index Ca and compression index Cc. It is postulated that the relation between time compressibility and effective stress compressibility holds true at any time, effective stress, and void ratio during consolidation. The observed values of Ca/Cc for a variety of natural soils, including highly sensitive clays, organic silts, and peats, are in the range of 0.025 to 0.10. The shape of the settlement curve in the secondary range can be predicted from the shape of the void ratio-logarithm of effective stress curve and the relationship between Ca and Cc. The predicted results are completely consistent with laboratory observations and with the existing field case records. The magnitude of Ca/Cc can be used to predict the shape of the volume change-logarithm of time curve in the transition from primary to secondary. The procedure provides a quantitative explanation for the observed shapes of the settlement curve.

Subject Headings: Effective stress | Curvature | Soil analysis | Soil compression | Compression | Clays | Soil settlement | Void ratio

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