Evolution of the Pore-Pressure Field around a Moving Conical Penetrometer of Finite Size
Publication: Journal of Engineering Mechanics
Volume 136, Issue 3
Abstract
A solution is developed for the evolution of buildup, steady, and postarrest dissipative pore-fluid pressure fields that develop around a finite-radius conical penetrometer advanced in a saturated linearly elastic porous medium. The analog with cone penetrometer testing is direct and is used to enable continuous distributions of permeability and diffusivity to be determined with depth. This analysis reveals the direct dependence of penetration rate on the induced fluid pressure field magnitudes, and predicts that a penetration rate threshold limit exists with respect to pore-pressure generation. This represents the essence of a partially drained system. The developed pore-pressure field is determined to be a function of the dissipation rate of the material, the penetration rate, and the storage effects of the advecting medium. Analysis of the pore-pressure field under start-up conditions reveals that the time required to reach steady state is strongly influenced by the penetration rate and the pressure-dissipation properties of the material. Analysis of the developed stable pressure fields illustrates the inversely proportional relationship that exists between penetration rate and pore-pressure magnitudes at the cone surface; representing the influence of storage in the medium on stable pore-pressure magnitudes. Stable pressure fields below the penetration threshold limit, , form a spherical response around the cone tip transitioning to an elongated radial response for penetration rates above this limit. Postarrest analysis indicates that the prearrest penetration rate strongly influences the dissipation rate and pattern of dissipation. The developed analysis can be correlated with CPTu-recovered data to independently evaluate permeability magnitudes during steady penetration.
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Acknowledgments
Funding for this research is provided by the U.S. National Science Foundation under Grant No. UNSPECIFIEDCMS-0409002 and a supplement provided through NSF-IREE-2006. The CPTu field data were collected by at the GEMS KGS/KSU field site [James Butler (KSU)] by Dr. Roman Hryciw (UM), and Dr. Dae Sung Lee (July 2005), with financial support from NSF. This support is gratefully acknowledged.
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Information & Authors
Information
Published In
Journal of Engineering Mechanics
Volume 136 • Issue 3 • March 2010
Pages: 263 - 272
Copyright
© 2010 ASCE.
History
Received: Apr 10, 2007
Accepted: Oct 20, 2009
Published online: Feb 12, 2010
Published in print: Mar 2010
Notes
Note. Associate Editor: Dinesh R. Katti
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