Location
Arlington, Virginia
Date
14 Aug 2008, 4:30pm - 6:00pm
Abstract
Automatic SPT hammers typically provide more transferred energy to drill rods than traditional safety hammers. This results in lower measured blow-counts from automatic hammers when compared to safety hammers. To eliminate such deviations in blow-counts, quality assurance for licensing new generation nuclear power plants requires that SPT energy measurements be made for each hammer used so that blow-counts can be corrected and be appropriately used in foundation design. A series of SPT hammer energy measurements was conducted on automatic hammers using a pile driving analyzer and employing the force velocity method to measure the actual energy transferred into the system. This paper reports the results of measurements for several such subsurface investigations. Altogether, over 220 energy measurements were made on 32 different automatic hammers. The soils ranged from soft clays to partially weathered rock, and the sampling depths ranged from a few feet to over 400 feet. The results obtained are compared to the results from the studies of Florida DOT and Utah DOT. Analysis of the 220 ETR measurements gives an overall average energy correction factor of 1.36, with high and low values of 1.46 and 1.25, respectively, obtained by applying the standard deviation.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
6th Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
Missouri University of Science and Technology
Document Version
Final Version
Rights
© 2008 Missouri University of Science and Technology, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Biringen, Emre and Davie, John, "SPT Automatic Hammer Efficiency Revisited" (2008). International Conference on Case Histories in Geotechnical Engineering. 14.
https://scholarsmine.mst.edu/icchge/6icchge/session04/14
SPT Automatic Hammer Efficiency Revisited
Arlington, Virginia
Automatic SPT hammers typically provide more transferred energy to drill rods than traditional safety hammers. This results in lower measured blow-counts from automatic hammers when compared to safety hammers. To eliminate such deviations in blow-counts, quality assurance for licensing new generation nuclear power plants requires that SPT energy measurements be made for each hammer used so that blow-counts can be corrected and be appropriately used in foundation design. A series of SPT hammer energy measurements was conducted on automatic hammers using a pile driving analyzer and employing the force velocity method to measure the actual energy transferred into the system. This paper reports the results of measurements for several such subsurface investigations. Altogether, over 220 energy measurements were made on 32 different automatic hammers. The soils ranged from soft clays to partially weathered rock, and the sampling depths ranged from a few feet to over 400 feet. The results obtained are compared to the results from the studies of Florida DOT and Utah DOT. Analysis of the 220 ETR measurements gives an overall average energy correction factor of 1.36, with high and low values of 1.46 and 1.25, respectively, obtained by applying the standard deviation.
