Studies on the Behavior of Single and Group of Geosynthetic Encased Stone Columns
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 136, Issue 1
Abstract
The stone columns (or granular piles) are increasingly being used as ground reinforcement elements for supporting a wide variety of structures including buildings and flexible structures. The stone columns derive their load capacity from the confinement offered by the surrounding soil. In very soft soils this lateral confinement may not be adequate and the formation of the stone column itself may be doubtful. Wrapping the individual stone columns with suitable geosynthetic is one of the ideal forms of improving the performance of stone columns. This type of encasement by geosynthetic makes the stone columns stiffer and stronger. In addition, encasement prevents the lateral squeezing of stones in to the surrounding clay soil and vice versa, preserves drainage function of the stone column and frictional properties of the aggregates. In spite of many advantages, the behavior and the mechanism of the geosynthetic encased stone columns is not thoroughly understood. This paper investigates the qualitative and quantitative improvement of individual load capacity of stone column by encasement through laboratory model tests conducted on stone columns installed in clay bed prepared in controlled condition in a large scale testing tank. The load tests were performed on single as well as group of stone columns with and without encasement. Tests were performed with different geosynthetics for the encasement of stone column. The results from the load tests indicated a clear improvement in the load capacity of the stone column due to encasement. The increase in the axial load capacity depends very much upon the modulus of the encasement and the diameter of the stone column. The increase in the stress concentration on the stone columns due to encasement was also measured in the tests. The results from the tests were used to develop the design guidelines for the design of geosynthetic encasement for the given load and settlement.
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Acknowledgments
The writers are thankful to the Ministry of Human Resources Development, Government of India, New Delhi for the financial assistance to the project titled “Investigations on Modern Technologies for Construction of Road/Rail Embankments on Soft Clay Soils” at IIT Madras. The writers acknowledge the help rendered by Mr. M. Gunasekaran at various stages during this work. The writers are thankful to the anonymous reviewers for their meticulous review and suggestions for improving the presentation in the paper.
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 136 • Issue 1 • January 2010
Pages: 129 - 139
Copyright
© 2010 ASCE.
History
Received: May 27, 2008
Accepted: Jun 29, 2009
Published online: Jul 1, 2009
Published in print: Jan 2010
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