Three-Dimensional Discrete-Element Method Analysis of Stresses and Deformations of a Single Geogrid-Encased Stone Column
Publication: International Journal of Geomechanics
Volume 17, Issue 9
Abstract
The discrete-element method (DEM) has been successfully used to simulate the behavior of granular material and was used in this study to analyze the stresses and deformations of a single geogrid-encased stone column under unconfined compression. The aggregate was simulated using graded particles of diameters ranging from 30 to 50 mm, and a biaxial geogrid as an encasement material was simulated using parallel-bonded particles. The micromechanical properties of the aggregate were determined using numerical triaxial tests at various confining stresses. The tensile properties of the geogrid were determined by a multirib tensile test, and the flexural rigidity of the geogrid was calibrated by a flexural bending test. This study investigated the changes in vertical and radial stresses and porosities, the contact-force distribution and particle movements within the aggregate, and the deformation and tensile force in the geogrid encasement. The load-displacement response of the DEM model of the geogrid-encased aggregate sample closely agreed with the experimental results. The coefficient of radial stress, defined as the ratio of vertical stress to radial stress within the aggregate, varied from 0.6 to 2.7 during loading where the tensile strength of the geogrid encasement was not fully mobilized. The aggregate showed volumetric contraction at small deformation and then dilation with an increase of deformation. The interlocking effects between the aggregate and the geogrid were observed at the initial state. The particles within the middle portion of the column were more likely to slip than those at other locations.
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Acknowledgments
This research was funded by the National Natural Science Foundation of China (NSFC Grant 51478178) and conducted while the first author visited the University of Kansas as a visiting scholar, which was supported by the China Scholarship Council (Grant 201406130006). The first author was granted temporary rights to use the PFC3D software through the Itasca Educational Partnership (IEP). The support is greatly appreciated.
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Published In
International Journal of Geomechanics
Volume 17 • Issue 9 • September 2017
Copyright
© 2017 American Society of Civil Engineers.
History
Received: Feb 9, 2016
Accepted: Mar 8, 2017
Published online: Jun 12, 2017
Published in print: Sep 1, 2017
Discussion open until: Nov 12, 2017
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