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|Title:||Procedures for prediction of consolidation in soft fine-grained dredged material|
|Authors:||Geotechnical Laboratory (U.S.)|
Dredging Operations Technical Support Program (U.S.)
Cargill, Kenneth W.
Fine grained soils
|Publisher:||Environmental Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
Abstract: The report documents studies refining the procedures for calculation of one-dimensional consolidation behavior of very soft fine-grained dredged material. Both tre conventional small strain theory of consolidation, which requires linear or constant soil properties, and the more general finite strain theory, which provides for nonlinear soil properties, are presented. Implications of the simplifying assumptions necessary in practical application of the theories are discussed and the general finite strain theory is shown to be superior for the treatment of dredged material. The governing equations for both theories are written in nondimensional terms and appropriate boundary and initial conditions are specified. Solutions in terms of figures relating the percent consolidation to the nondimensional time factor for small strain theory have been previously published. However, similar solutions based on the finite strain theory were not available and thus had to be developed. Using a computer program, a linearized nondimensional form of the general finite strain governing equation was solved for the cases of singly/doubly drained normally consolidated clays, and singly/doubly drained dredged fill. The figures given represent a significant advancement in the ability to accurately predict the consolidation behavior of thick deposits of very soft fine-grained materials having nonlinear soil properties. A method of obtaining soil parameters necessary for use of the new solution charts is proposed. A procedure for calculating consolidation of multiple lifts of material placed on prior lifts of underconsolidated material is also proposed and validated by using the procedure to predict settlements of actual field sites where settlements have been measured. For two of three field sites, good agreement was obtained between predictions and measurements when the finite strain theory and the proposed solution technique were used. Behavior at the third site was not well predicted due to the geometry of the site and its particular filling history. In all cases, the finite strain theory solutions were far more accurate than small strain theory solutions. The calculation procedure is also applicable to a single lift subjected to multiple surcharge loadings as would be the case in a phased construction. This report concludes that the nondimensional finite strain solutions offer more realistic estimates of soft fine-grained material consolidation than similar small strain solutions and that the procedure proposed for multiple lifts is applicable to field problems. The report recommends the use of given finite strain solutions and procedures for prediction of consolidation behavior of fine-grained dredged material deposited in confined disposal areas. NOTE: This file is large. Allow your browser several minutes to download the file.
|Appears in Collections:||Technical Report|