Model Tests to Determine Properties of Concrete and Aggregates in Verification Core Holes at the Bottom of Drilled Shafts
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 147, Issue 9
Abstract
Verification core holes are important tools in ascertaining the properties of the bed rock at the bottom of drilled shafts. However, it is unknown whether verification core holes fill during concrete placement; if they fill, the mechanical properties of the filling are unknown. The diameters of the core holes are in the range, and core holes are at least long; empty core holes or core holes filled with weak and deformable materials may significantly decrease the capacity of drill shafts. The paper describes the experiments performed to answer these two questions by using 15- and verification core hole models, and drilled shaft depths between 9- and 30-m depth. The smallest slump allowed by the Texas Department of Transportation (TxDOT) was used: 15 and in dry and wet conditions, respectively. In dry conditions, verification core holes completely filled with concrete, whose compressive strength exceeded the TxDOT specifications. The compressive strength of the concrete obtained in the core holes was higher than the concrete strength in the core holes by 60% to 150%. In wet conditions, unless the tremie or pump pipe was inserted into the bottom of the core hole, the bottom half of the verification core filled with uncemented gravel–sand mixture (angle of internal friction, ), while the upper half of the verification core filled with weakly cemented material whose P-wave velocity was found to be .
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Data Availability Statement
All data, models, and code generated or used during the study appear in the published article.
Acknowledgments
The research is part of Project “TxDOT 0-5825: Influence of Verification Cores on Point Bearing Capacity of Drilled Shafts” sponsored by the Texas Department of Transportation. The authors would like to thank the anonymous reviewers, the associate editors, and the editors for their time and effort in reviewing the paper.
References
ACI (American Concrete Institute). 2014. Building code requirements for structural concrete and commentary. Farmington Hills, MI: ACI.
Anay, R. 2008. “Investigation of concrete flow into the verification cores at the bottom of drilled shafts.” M.S. thesis, Dept. of Civil, Environmental, and Architectural Engineering, Univ. of Texas at Austin.
ASTM. 2004. Standard test method for direct shear test of soils under consolidated drained condition. West Conshohocken, PA: ASTM.
ASTM. 2005. Standard test method for compressive strength of cylindrical concrete specimens. West Conshohocken, PA: ASTM.
ASTM. 2014. Standard specification for concrete aggregates. West Conshohocken, PA: ASTM.
McClelland, M. 2005. “Deep foundations for transportation facilities.” Accessed December 1, 2009. http://cigmat.cive.uh.edu/sites/cigmat/files/files/conference/presentation/2005/3.pdf.
Ou, C. Y. 2006. Deep excavations: Theory and practice. London: Taylor & Francis.
Terzaghi, K., R. B. Peck, and G. Mesri. 1996. Soil mechanics in engineering practice. 3rd ed. New York: Wiley.
TxDOT (Texas Department of Transportation). 2014. Standards specifications for construction and maintenance of highways, streets and bridges. Austin, TX: TxDOT.
Vipulanandan, A. C., A. Hussain, and O. Usluogulari. 2007. “Parametric study of open core-hole on the behavior of drilled shafts socketed in soft rock.” In GeoDenver 2007: Contemporary Issues in Deep Foundations, Geotechnical Special Publication 158, edited by W. Camp, R. Castelli, D. F. Laefer, and S. Paikowsky. Reston, VA: ASCE.
Youn, H., and F. Tonon. 2010. “Numerical study of the effect of verification core hole on the point bearing capacity of drilled shafts.” J. Geotech. Geoenviron. Eng. 136 (9): 1287–1297. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000333.
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© 2021 American Society of Civil Engineers.
History
Received: Dec 5, 2009
Accepted: Mar 5, 2021
Published online: Jul 13, 2021
Published in print: Sep 1, 2021
Discussion open until: Dec 13, 2021
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