Piecewise-Linear Formulation of Coupled Large-Strain Consolidation and Unsaturated Flow. II: Testing and Performance
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 143, Issue 7
Abstract
A piecewise-linear formulation for simulating coupled large-strain consolidation and unsaturated flow using a mass-conservative and noniterative solution was developed in a companion paper and implemented in a proposed program called UNSAT-CON. The formulation is tested in this paper using numerical cases as well as laboratory and field data. First, UNSAT-CON is tested by comparing model predictions to published predictions of a finite-element-based model that uses a quasi-unsaturated formulation to model evaporation: the same quasi-unsaturated formulation is implemented in UNSAT-CON to allow direct comparison. Excellent agreement of settlement over time for various levels of evaporation are obtained. UNSAT-CON reliably predicts the hydraulic exchange at the soil–atmosphere interface under the conditions of evaporation, decantation, or their combinations. The fully unsaturated formulation is tested on fine-grained tailings by calibration with a documented laboratory column test and verification with a 4.1-m-deep field trial. This testing exercise showed (1) three-dimensional (3D) constitutive surfaces are largely constrained when defined using conventional test data such as the saturated compressibility function and soil water characteristic curve; (2) good to excellent agreement between measurements and predictions are observed, including the developing suction, decreasing void ratio, increasing solid content, and increasing settlement rate due to evaporation effect on the near surface zone; and (3) modeling desaturation allows for a more-realistic simulation of deformation in the unsaturated zone than using formulations that do not model desaturation.
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Acknowledgments
This research was funded by a Collaborative Research and Development Grant jointly funded by the Canadian Oil Sands Alliance and Natural Science and Engineering Research Council of Canada (NSERC). Logistical support by Shell Canada, Barr Engineering, and O’Kane Consultants is gratefully acknowledged.
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©2017 American Society of Civil Engineers.
History
Received: Feb 8, 2016
Accepted: Sep 26, 2016
Published online: Mar 1, 2017
Published ahead of print: Mar 3, 2017
Published in print: Jul 1, 2017
Discussion open until: Aug 1, 2017
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