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55 GLOSSARY Beginning of restrike (BOR): The first few restrike blows after a period of time. Drivability analysis: An analysis of the maximum driv- ing resistance and the installation equipment in order to evaluate whether a hammer and driving system will likely install the pile to the required depth or resistance in a sat- isfactory manner. Dynamic analysis method: Using dynamic formulas and/or test data to calculate pile resistance. Dynamic monitoring: A measure of the behavior of the pile during one or more hammer blows in which instrumenta- tion on the pile is used to obtain measurements of strain and acceleration. The Pile Driving Analyzer® (PDA) is a commonly used apparatus for dynamic monitoring. Dynamic pile driving formula: A closed form equation, such as the Gates or Engineering News formulas, used to relate pile hammer characteristics and penetration to the axial static resistance of the pile. End-of-initial driving (EOID): The last few blows during the initial installation of a driven pile. High-strain dynamic test: The procedure for monitoring dynamically loaded deep foundations and estimating static axial resistance as described by ASTM D4945. LDOEP (large diameter open-ended pile): An open-ended pipe pile made of either steel or concrete with a diameter that is 36 in. or greater. Also referred to as cylinder piles. Maximum driving resistance: The maximum amount of axial resistance that must be overcome in order to install the pile to the minimum pile penetration and to achieve the nomi- nal bearing resistance. The maximum axial resistance that must be overcome includes the nominal bearing resistance plus any axial resistance present at the time of driving within zones of soil that may be removed in the future by scour or that may be subject to downdrag. Nominal unit base resistance: The resistance to static axial compression loading on the base of the pile, at the strength limit state. Nominal unit side resistance: The resistance to static axial compression or tension loading along the exterior or interior surface along the length of a pile, at the strength limit state. Penetration resistance: A measure of the resistance to penetra- tion of the pile during driving. May be expressed as blows per foot (b/f or blow count), blows per inch (bpi), or set per blow (inches). Pile driving criteria: A specific set of requirements used to define the conditions that must be met during the installa- tion of a production pile. Usually involves some combina- tion of minimum embedment and/or penetration, the latter related to specific installation equipment. Plugged condition or plug: A condition when the soil column inside of the interior of the pile moves downward with the pile, closing the end of the pile. This causes the pile to behave as a closed-end pile during driving or during static loading. Production pile: A pile that will become part of the permanent foundation for the structure. Rapid load test: The application of a force pulse to perform a load test of a deep foundation element as described by ASTM D7383. The Statnamic® (STN) loading device is a commonly used method for performing a rapid load test. Relaxation: A reduction in the axial resistance after a period of time. Restrike: A hammer blow or series of hammer blows applied to a pile after a period of time ranging from hours to days dur- ing which the pile is not actively driven. Restrike blows are applied to provide a measure of setup or relaxation after the initial driving of the pile. Setup: An increase in the axial resistance of a pile that devel- ops over time. Signal matching: Numerical analysis of the pile based on the results of a high-strain dynamic test to determine static axial resistance. The CAPWAP® (Case Pile Wave Analysis Program) is an example of a computer code used for signal matching. Soil column: The soil that is inside the interior of the open- ended pile. The soil column may or may not move with the pile as the pile is driven into the ground. Static analysis method: Using static formulas, correlations, and/or static load test data to calculate pile resistance. Static load test: The application of a static force to perform a load test of a deep foundation element as described by ASTM D1143. Test pile: A pile that is installed for the primary purpose of performing a test of the pile, including the behavior during installation and/or during subsequent testing to determine the axial resistance. A test pile may or may not be incorporated into the permanent foundation as a production pile. Wave equation analysis: Numerical model of the specific pile, soil conditions, and installation equipment used to evaluate behavior of the pile and driving equipment for a specific project.
