K(o)-Behavior of Normally Consolidated Fine-Grained Soils during One-Dimensional Secondary Compression Aging and the Quantitative Prediction of the Quasi-Preconsolidation Effect.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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No consensus and little experimental evidence exist in the geotechnical engineering community regarding k sub o behavior of normally consolidated fine-grained soils during one-dimensional secondary compression aging and the origin and magnitude of the quasi-preconsolidation effect. After reviewing several concepts, a control volume triaxial-type test cell with support systems was developed. This equipment allows the maintenance and measurement of the k sub o condition during consolidation. Design considerations, development history, and performance parameters for the system are provided. Six normally consolidated fine-grained specimens, three Edgar Plastic Kaolinite and three Agsco novaculite, were allowed to age a minimum of 14 days under a 2 tsf vertical stress while the k sub o condition was maintained and measured. The specimens were loaded in small increments following aging to determine if the quasi-preconsolidation effect had developed. Results show k sub o decreases during secondary aging in one-dimensional compression for normally consolidated fine-grained soils. Moreover, the quasi-preconsolidation effect develops in both cohesive and cohesionless fine-grained soils. This suggests the quasi-preconsolidation effect develops due to increased friction rather than bonding as previously proposed. Finally, results indicate the existing theory for predicting the magnitude of the quasi-preconsolidation effect needs further refinement. Author.
- Soil Mechanics