PILE LOAD TEST BY IMPACT DRIVING

THE USE OF MEASUREMENTS MADE DURING IMPACT DRIVING TO PREDICT STATIC PILE CAPACITY IS A WIDELY USED CONCEPT. THE RESULTS ARE SOMETIMES NOT SATISFACTORY BECAUSE OF A LACK OF KNOWLEDGE OF HAMMER ENERGY, POOR ESTIMATES OF LOSSES IN CUSHIONS, INACCURATE SET MEASUREMENTS, SUBSTANTIAL STRENGTH CHANGE AFTER THE END OF DRIVING, AND OTHER FACTORS. A METHOD HAVING A DIFFERENT BASIS HAS BEEN PROPOSED FOR PREDICTING STATIC CAPACITY FROM DYNAMIC MEASUREMENTS MADE BY IMPACT DRIVING. BY APPLYING THIS METHOD TO MEASUREMENTS MADE AFTER A SETUP PERIOD, THE DIFFICULTIES MENTIONED ARE AVOIDED. THIS METHOD HAS BEEN APPLIED TO 25 PILES THAT WERE ALSO STATICALLY LOAD-TESTED. THE AVERAGE DIFFERENCE BETWEEN THE STATIC CAPACITY OBTAINED FROM A CONSTANT RATE OF PENETRATION TEST AND THAT PREDICTED FROM DYNAMIC MEASUREMENTS WAS 10 PERCENT. A WIDE VARIETY OF SOIL CONDITIONS AND HAMMER TYPES IS REPRESENTED IN THE DATA. ALL PILES WERE OF HOLLOW STEEL PIPES. THE USE OF THIS SYSTEM FOR ROUTINE MEASUREMENTS IS NOT FEASIBLE IF RELIANCE MUST BE PLACED ON THE ANALYSIS OF RECORDS TAKEN ON HIGH-SPEED OSCILLOGRAPHS BECAUSE A SUBSTANTIAL TIME LAG OCCURS BETWEEN DATA ACQUISITION AND ANALYSIS. IN ADDITION, EQUIPMENT OF THIS TYPE IS HARDLY SATISFACTORY FOR ROUTINE FIELD USE BY PERSONNEL HAVING MODEST BACKGROUNDS IN ELECTRONICS. TO AVOID THESE PROBLEMS, A SPECIAL PURPOSE COMPUTER WAS DESIGNED AND CONSTRUCTED TO PERFORM THE NECESSARY COMPUTATIONS IN THE FIELD AND TO DISPLAY THE RESULTS. WITH THIS DEVICE, THE NECESSARY CALCULATIONS FOR CAPACITY PREDICTION ARE MADE IN REAL TIME AND THE RESULTS ARE DISPLAYED. THUS A NUMBER OF CONSECUTIVE BLOWS CAN BE RECORDED TO IMPROVE THE ACCURACY OF THE PREDICTION. THIS DEVICE SHOULD IMPROVE THE RELIABILITY OF PILE TEST DATA BECAUSE IT IS REALISTIC TO OBTAIN LOAD TEST DATA BY DRIVING A NUMBER OF "TEST" PILES AND OBTAINING DYNAMIC PREDICTIONS FROM ALL OF THEM. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1970/333/333-012.pdf
• Supplemental Notes:
  • Paper sponsored by Committee on Construction Practices--Structures and presented at the 49th Annual Meeting. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Goble, G G
  • Rausche, Frank
• Conference:
  • 49th Annual Meeting of the Highway Research Board
  • Location: Washington District of Columbia, United States
  • Date: 1970-1-12 to 1970-1-16
• Publication Date: 1970

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 123-129
• Monograph Title: Pile foundations
• Serial:
  • Highway Research Record
  • Issue Number: 333
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Accuracy; Data collection; Impacts; Information processing; Loads; Measurement; Pile driving; Soil penetration test; Static loads; Structural tests; Support piles
• Old TRIS Terms: Field records; Pile bearing capacities; Pile lateral loads; Pile tests
• Subject Areas: Bridges and other structures; Geotechnology; Highways;

Filing Info

• Accession Number: 00233013
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: May 26 1971 12:00AM