Developing Production Pile Driving Criteria from Test Pile Data (2011) / Chapter Skim
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14 INTRODUCTION The Phase I Survey (Appendix A) was developed to gather information on how the surveyed agencies were developing and using pile driving criteria.
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15 In the following discussions where respondents were asked to provide numerical answers an attempt has been made to utilize answers that indicate a majority. That is, when an agency had values among several options, the option with the majority was typically taken as the "predominate" method or answer.
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the contractor to submit an installation plan for driven piles that includes the following: a. No submittal required 50% to 100%, with 3 of 42 states listing as primary method.
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17 b. Specified hammer energy included in specifications 5% to 100%, with 12 of 42 states listing as primary method.
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18 TABLE 5 Q4. PLEASE PROVIDE YOUR BEST ESTIMATE OF THE PERCENTAGE OF DRIVEN PILES (e.g., out of the total number of driven piles used for transportation structures on an annual basis)
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19 TABLE 5 (continued) State 4a 4b 4c 4d 4e Ohio 100% Oregon The method for determining the suitability of hamm ers depends on the method being used to deter mi ne bearing.
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Questions 5–9: Current Practice Question 5 -- Predominant Criteria 5. Please estimate the percentage of driven pile projects for which the predominant method your agency uses as a criteria for installation of production piles is the following: a.
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22 State 5a 5b 5c 5d 5e 5f 5g Missouri 75% -- Modified Gates Verified 15% -- Modified Gates Controlled 10% -- Modified Gates Verified Nebraska All projects If we specify test piles on the project Nevada 100%, also mu st meet required blow count 100%, also mu st meet tip elevation requirem ents 90% <10% <5% New Ham pshire 100% 2% 100% New Jersey 95% of production piles driving criteria are based on the test piles driving data that are subjected to PDA/CAPWAP measurem ents. 5% of production pile driving criteria ma y be based on data from SLT and PDA/CAPWAP perform ed to the test piles.
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This question required a narrative answer from the respondents. The survey answers for Question 7 are listed in Table 8.
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25 TABLE 8 (continued) New Ham pshire 100%.
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such as very large projects, certain soil conditions, or other special circumstances. Some states that have had limited use of dynamic monitoring indicated that they foresee increased use of the technology as they fully transition to LRFD design to take advantage of the higher resistance factors associated with dynamic monitoring.
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27 TABLE 9 Q8. PLEASE ESTIMATE THE PERCENTAGE OF DRIVEN PILE PROJECTS FOR WHICH YOUR AGENCY WOULD UTILIZE TESTING OF PRE-PRODUCTION (test or probe)
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28 TABLE 9 (continued) State 8a 8b 8c 8d 8e New York 96% 2% 2% North Carolina One every other year North Dakota 100% 3% Ohio 100% Oregon <1% South Carolina 99% 1% South Dakota Tennessee 50% 50% Utah 98% 2% Vermont 98% Virginia 30% -- These are endbearing piles driven to refusal.
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29 TABLE 10 (continued) State New Jersey N/A New Mexico N/A New York We rarely have used test progra ms during the design stage of the project; in fact, I can only think of one project where we did th is.
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31 a single pile type is exclusively used or is very predominate in the particular states.
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typically have small projects or a low volume of piles on an annual basis. Such states typically responded that they consider tests on very large projects, but do not necessarily require them.
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33 addition of base resistance from one blow with the side resistance of a different blow. There are cases where such an analysis may be warranted, such as when the hammer does not sufficiently move the pile during a restrike to be confident that the full pile resistance was mobilized.
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34 TABLE 12 (continued) State 15a 15b Michigan Typically restrike is avoided unless piles are in silts and/or silty clays.
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35 TABLE 12 (continued) State 15a 15b Washington In such cases, restrike is performed about 70% of the time; however, we might not do restrike if in relatively clean sands or gravels.
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36 TABLE 13 (continued) State 15c 15d Mississippi Generally use one of the early "high energy" blows No Missouri Nebraska Average of 10 blows No Nevada Warm up ham mer on different pile for a minim um of 20 blows.
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37 during design or submittal review to produce the criteria. Some utilize criteria of blow count versus resistance based on the test results, whereas others calculate a minimum blow count for a minimum hammer energy or stroke.
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When the NYSDOT uses HSDT to establish the driving criteria for cast-in-place or H-piles, one test pile (a production pile) per substructure is tested at initial drive and with a 24-h restrike.
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39 WSDOT uses SLT on large diameter piles, using the data to back correlate soil parameters and then adjust the static pile analysis. Piles are then driven to a design tip elevation based on the revised static analysis, rather than to a criteria established by formula or HSDT.
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