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Evaluation of Phosphatic Clay Disposal and Reclamation Methods. Volume 8: Predictive Methodology Applied to Case Histories

02-073-097Final

Abstract

To refine the predictive model for phosphatic clay and sand-clay mix consolidation, a Phase II field testing program was performed at three selected sites utilizing conventional, sand-clay mix, and flocculated clay disposal methods. Principal generalized findings include the following:

* Underlying cast spoil material generally serves as a lower drainage boundary during consolidation of phosphatic clays and sand-clay mixes.

* The use of laboratory determined compressibility properties to predict the in situ compressibility of phosphatic clays is justified.

* Piezocone soundings can be advantageously used to estimate the in situ undrained shear strength and, hence, effective stresses of normally consolidated phosphatic clays and sand-clay mixes.

A simplified and practical empirical model for estimating the consolidation properties of phosphatic clays and sand-clay mixes, based on index properties, is presented. The recommended semi-empirical relations are based on previous findings and may be used in the absence of site specific consolidation data.

Finally, the predictive methodology was calibrated based on predictions made from laboratory test data and program SLURRY, and comparison of the predictions to field measurements. In order to accurately model field conditions, it is concluded that the coefficient of permeability determined from laboratory tests, and/or from empirical correlations, may have to be increased to account for the fact that the in situ coefficient of permeability is often greater than backfigured from laboratory tests.

Evaluation of Phosphatic Clay Disposal and Reclamation Methods.
Other Volumes.

FIPR Publication No. 02-002-003
Volume 1: Index Properties of Phosphatic Clays.

FIPR Publication No. 02-002-004
Volume 2: Mineralogy of Phosphatic Clays.

FIPR Publication No. 02-002-005
Volume 3: Sedimentation Behavior of Phosphatic Clays.

FIPR Publication No. 02-002-008
Volume 4: Consolidation Behavior of Phosphatic Clays.

FIPR Publication No. 02-002-023
Volume 5: Shear Strength Characteristics of Phosphatic Clays.

FIPR Publication No. 02-002-024
Volume 6: Predictive Methodology for Evaluating Disposal Methods.

FIPR Publication No. 02-042-044
Volume 7: Engineering Properties of Flocculated Phosphatic Clays.