Use of Time-Domain Reflectometry for Quality Control of Soil-Nailing Works
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 12
Abstract
Soil nailing is an effective and practical means for stabilizing slopes and supporting excavations. It has been used extensively in slope improvement works in Hong Kong since the mid-1990s. However, once a soil nail has been installed, it is difficult to check its quality, such as the length of the steel bar and the integrity of cement grout annulus. To enhance the quality control of soil-nail installation works, the Geotechnical Engineering Office (GEO) of the Civil Engineering and Development Department in Hong Kong has carried out a study to identify and develop nondestructive means for checking the quality of installed soil nails. Among the various techniques tried, time-domain reflectometry (TDR) was found to be the simplest, quickest, and least expensive. Since then, a large number of field measurements have been taken to gain experience on the practicality and reliability of this technique. In mid-2004, the GEO introduced TDR to its soil-nailing works under the Landslip Preventive Measures Programme for pilot use during independent site audits. In 2007, an independent review was carried out that supports the continual use of TDR in the program and suggests further enhancement of the sampling strategy of the assurance program. This paper gives an overview of the use of TDR in assessing the quality of steel soil nails with preinstalled wires. The sources of uncertainty in relation to the test are discussed. It also describes cases in which TDR has identified anomalies and the corresponding follow-up actions.
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Acknowledgments
This paper is published with the permission of the Head of the Geotechnical Engineering Office and the Director of Civil Engineering and Development of the Government of the Hong Kong Special Administrative Region.
References
Agilent Technologies. (1998). Time domain reflectometry theory (application note 1304-2), Santa Clara, CA, 2, 14.
Ang, A. H.-S., and Tang, W. H. (1984). Probability concepts in engineering planning and design: Decision, risk, and reliability, Wiley, New York.
Ang, A. H-S., and Tang, W. H. (2006). Probability concepts in engineering, Wiley, New York.
British Standards Institution (BSI) (1994a). “Accuracy (trueness and precision) of measurement methods and results—Part 1: General principles and definitions.” BS ISO 5725-1, London.
British Standards Institution (BSI) (1994b). “Accuracy (trueness and precision) of measurement methods and results—Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method.” BS ISO 5725-2, London.
Cheung, W. M. (2003). “Non-destructive tests for determining the lengths of installed steel soil nails.” GEO Rep. No. 133, Civil Engineering and Development Dept., Geotechnical Engineering Office, Hong Kong, 〈http://www.cedd.gov.hk/publications/〉.
Cheung, W. M., and Lo, D. O. K. (2005). “Interim report on non-destructive tests for checking the integrity of cement grout sleeve of installed soil nails.” GEO Rep. No. 176, Civil Engineering and Development Dept., Geotechnical Engineering Office, Hong Kong, 〈http://www.cedd.gov.hk/publications/〉.
Cheung, W. M., Shum, K. W., and Cheng, F. K. (2008). “Use of time domain reflectometry to determine the length of steel soil nails with grout pipe with embedded copper wires.” GEO Rep. No. 228, Civil Engineering and Development Dept., Geotechnical Engineering Office, Hong Kong, 〈http://www.cedd.gov.hk/publications/〉.
Dowding, C. H., and Huang, F. C. (1994). “Early detection of rock movement with time domain reflectometry.” J. Geotech. Eng., 120(8), 1413–1427.
Geotechnical Engineering Office (GEO) (2004). “Acceptance of methods for quality control,” GEO Technical Guidance Note No. 18, Civil Engineering and Development Dept., Geotechnical Engineering Office, Hong Kong, 〈http://www.cedd.gov.hk/publications/〉.
Lee, C. F., and Ove Arup & Partners Hong Kong Limited (OAP) (2007). “Review of use of non-destructive testing in quality control in soil nailing works.” GEO Rep. No. 219, Civil Engineering and Development Dept., Geotechnical Engineering Office, Hong Kong, 〈http://www.cedd.gov.hk/publications/〉.
Lin, C. P., and Tang, S. H. (2005). “Development and calibration of a TDR extensometer for geotechnical monitoring.” Geotech. Test. J., 28(5), 464–471.
Liu, W., Hunsperger, R., Chajes, M., Folliard, K., and Kunz, E. (2002). “Corrosion detection of steel cables using time domain reflectometry.” J. Mater. Civ. Eng., 14(3), 217–223.
O’Connor, K. M., and Dowding, C. H. (1999). Geomeasurements by pulsing TDR cables and probes, CRC Press, Boca Raton, FL.
Reynolds, J. M. (1997). An introduction to applied and environmental geophysics, Wiley, New York.
Siddiqui, S. I., Drnevich, V. P., and Deschamps, R. J. (2000). “Time domain reflectometry for use in geotechnical engineering.” Geotech. Test. J., 23(1), 9–20.
Topp, G. C., Davis, J. L., and Annan, A. P. (1980). “Electromagnetic determination of soil water content: Measurement in coaxial transmission lines.” Water Resour. Res., 16(3), 574–582.
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© 2011 American Society of Civil Engineers.
History
Received: May 13, 2009
Accepted: Apr 12, 2011
Published online: Apr 14, 2011
Published in print: Dec 1, 2011
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