High Strain Dynamic Pile Testing and SPT Hammer Calibration

High strain dynamic pile testing is performed during pile installation to provide an assessment of pile capacity and integrity.  The test is performed by attaching strain gages and accelerometers to the top of the pile.

Signals from the gages are recorded by a Pile Driving Analyzer (PDA).  FTC utilizes a wireless communication system between the pile mounted gages and the PDA computer thereby eliminating the need for a main connecting cable.  The wireless system allows for faster, more efficient testing and minimizes the chance for any testing delay associated with cable handling.

It is also possible to efficiently perform PDA tests for several pile each day with one operator.  All pile types including concrete, steel pipe pile or steel H-pile, auger cast pile or even drilled shafts can be tested with the PDA equipment.

PDA testing provides many advantages such as being able to confirm the geotechnical capacity of the pile during installation and the ability to monitor pile driving stresses and hammer efficiency.  PDA testing, when used as part of an overall geotechnical design program can allow for more efficient pile design (fewer or shorter piles compared to using a pile design with a higher factor of safety or lower geotechnical phi factor where pile installation testing was not performed).  The switch from allowable stress design to load and resistance factor design for federally funded and other projects has typically resulted in a greater amount of pile testing.  This is because the uncertainties associated with pile capacity (soil resistance) are greater than the uncertainties associated with the structural capacity of the pile.  The soil resistance can be better quantified by measuring the dynamic resistance and estimating the static resistance with the PDA during pile installation.

Related services that are available from FTC include wave equation analysis (WEAP) to assess hammer selection and drivability, CAPWAP signal matching analysis for pile capacity computation and for refined wave equation analysis (WEAP).

It is important for PDA testing to be performed by qualified and experienced staff.  FTC has provided PDA testing services at many major bridge projects throughout the United States.  FTC has highly qualified and experienced staff performs our services in a highly efficient and responsive manner.