Refined True Triaxial Apparatus for Testing Unsaturated Soils under Suction-Controlled Stress Paths
Publication: International Journal of Geomechanics
Volume 12, Issue 3
Abstract
This paper introduces a servocontrolled true triaxial apparatus that has been developed to test cubical specimens [with 7.62 cm (3 in.) sides] of unsaturated soil under controlled-suction states and for a wide range of stress paths not readily achievable in a cylindrical cell. The apparatus is a mixed-boundary-type device, with the specimen seated on top of a 5-bar high-air-entry-value (HAEV) ceramic disk and between five flexible membranes on the remaining sides of the cube. The new cell is an upgraded, more elaborate version of one previously reported by the authors, featuring two independent pore-air and pore-water pressure control systems, as well as a fully computer-driven stress application/control system. Suction states are induced in the specimens via the axis-translation technique. The paper outlines the full development of the apparatus, including its main components; assembling process; and selection of appropriate compaction method, dry unit weight, and constant-suction loading rate for clayey sand. The suitability of the apparatus is demonstrated by repeatable results from two triaxial compression tests performed on identically prepared samples of compacted clayey sand under constant 200-kPa matric suction.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The true triaxial apparatus was developed under U.S. National Science Foundation Award No. CMS-0216545. This support is gratefully acknowledged. Any findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF. The authors also thank Dr. Manuel Padilla of GCTS and Professor Stein Sture of the University of Colorado at Boulder for all their technical assistance, especially in the manufacturing of the basic core system during the early stages of this research effort.
References
Alonso, E. E., Gens, A., and Josa, A. (1990). “A constitutive model for partially saturated soils.” Geotechnique, 40(3), 405–430.GTNQA8
Arthur, J. R. F. (1988). “Cubical devices: versatility and constraints.” Advanced triaxial testing of soil and rock (STP 977), Donaghe, R. T., Chaney, R. C. and Silver, M. L., eds., ASTM, Philadelphia, 743–765.
Bishop, A. W., and Gibson, R. E. (1963). “The influence of the provisions for boundary drainage on strength and consolidation characteristics of soils measured in the triaxial apparatus.” ASTM Special Technical Publication No. 361, ASTM, Philadelphia, 435–458.
Bishop, A. W., and Henkel, D. J. (1962). The measurement of soil properties in the triaxial test, 2nd Ed., Edward Arnold, London.
Brooks, R. H., and Corey, A. T. (1964). “Hydraulic properties of porous media.” Hydrology Paper No. 3, Colorado State Univ., Fort Collins, CO.
Fredlund, D. G. (1973). “Volume change behavior of unsaturated soils.” Ph.D. dissertation, Univ. of Alberta, Edmonton, AB, Canada.
Fredlund, D. G., and Rahardjo, H. (1993). Soil mechanics for unsaturated soils, Wiley, New York.
Fredlund, D. G., and Xing, A. (1994). “Equations for the soil-water characteristic curve.” Can. Geotech. J.CGJOAH, 31(4), 521–532.
Geotechnical Consulting and Testing Systems (GCTS). (2004a). Digital servo controller user’s guide, GCTS, Tempe, AZ.
Geotechnical Consulting and Testing Systems (GCTS). (2004b). Universal program user’s guide, GCTS, Tempe, AZ.
Ho, D. Y. F., and Fredlund, D. G. (1982). “Strain rates for unsaturated soil shear strength testing.” Proc., 7th Southeast Asian Geotechnical Conf., Hong Kong, Vol. 1, 787–803.
Hoyos, L. R., Laikram, A., and Puppala, A. J. (2005). “A novel true triaxial apparatus for testing unsaturated soils under suction-controlled multi-axial stress states.” Proc., 16th Int. Conf. on Soil Mechanics and Geotechnical Engineering (CD-ROM), Millpress, Osaka, Japan, 387–390.
Hoyos, L. R., Laikram, A., and Puppala, A. J. (2008). “A novel suction-controlled true triaxial apparatus for unsaturated soils.” Chapter 5, Unsaturated soils: Advances in geo-engineering, Toll, D. G., Augarde, C. E., Gallipoli, D. and Wheeler, S. J., eds., CRC, London, 83–88.
Hoyos, L. R., and Macari, E. J. (2001). “Development of a stress/suction-controlled true triaxial testing device for unsaturated soils.” Geotech. Test. J., 24(1), 5–13.GTJODJ
Hoyos, L. R., Pérez-Ruiz, D. D., and Puppala, A. J. (2012). “Modeling unsaturated soil response under suction controlled true triaxial stress paths.” Int. J. Geomech., 12(3), 292–308.IJGNAI
Janoo, V. C. (1986). “Drained and undrained behavior of sand under high pressures.” Ph.D. dissertation, Univ. of Colorado at Boulder, Boulder, CO.
Lu, N., and Likos, W. J. (2004). Unsaturated soil mechanics, Wiley, Hoboken, NJ.
Macari, E. J., and Hoyos, L. R. (2001). “Mechanical behavior of an unsaturated soil under multi-axial stress states.” Geotech. Test. J., 24(1), 14–22.GTJODJ
Matsuoka, H., Sun, D. A., Kogane, A., Fukuzawa, N., and Ichihara, W. (2002). “Stress-strain behaviour of unsaturated soil in true triaxial tests.” Can. Geotech. J.CGJOAH, 39(3), 608–619.
Pérez-Ruiz, D. D. (2009). “A refined true triaxial apparatus for testing unsaturated soils under suction-controlled stress paths.” Ph.D. dissertation, Univ. of Texas at Arlington, Arlington, TX.
Sture, S. (1979). “Development of multiaxial cubical test device with pore-water pressure monitoring facilities.” Rep. No. VPI-E-79.18, Dept. of Civil Engineering., Virginia Polytechnic Institute and State Univ., Blacksburg, VA.
Sture, S., and Desai, C. S. (1979). “Fluid cushion truly triaxial or multiaxial testing device.” Geotech. Test. J., 2(1), 20–33.GTJODJ
van Genuchten, M. T. (1980). “A closed-form equation for predicting the hydraulic conductivity of unsaturated soils.” Soil Sci. Soc. Am. J.SSSJD4, 44(5), 892–898.
Wheeler, S. J., and Sivakumar, V. (1995). “An elasto-plastic critical state framework for unsaturated soils.” Geotechnique, 45(1), 35–53.GTNQA8
Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 12 • Issue 3 • June 2012
Pages: 281 - 291
Copyright
© 2012. American Society of Civil Engineers.
History
Received: Nov 19, 2010
Accepted: Apr 29, 2011
Published online: May 2, 2011
Published in print: Jun 1, 2012
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.