LABORATORY MEASUREMENT OF FOUNDATION SOIL RESPONSE OF EMBANKMENTS DURING STAGE CONSTRUCTION

摘要

This paper presents results from a laboratory test program designed to simulate, at the element level, the stress conditions within the foundation soil of a stage constructed embankment. Direct simple shear (DSS) tests were conducted on two low plasticity clays representing two extremes of soil sensitivity. Tests were conducted on resedimented Boston Blue Clay and on undisturbed samples of the high sensitivity Gloucester Leda clay. Consolidation states consisted of traditional K_0 consolidation (CK_0U) to measure the reference undrained stress-strain-strength behavior and anisotropic consolidation (CAU) to simulate stage construction. CAU tests involved applying a vertical effective stress and a horizontal shear stress during consolidation, which is a more realistic representation of the stress conditions within the foundation soil of a stage constructed embankment. The CAU tests produced a marked difference in the stress-strain-strength behavior for both soils in comparison with the CK_0U tests. The CAU tests exhibited a more brittle stress-strain response and, more significantly for design, a greater undrained shear strength for all test conditions used. These results are potentially significant for stage construction design, particularly for cases that have marginal factors of safety using traditional CK_0U design strengths.