PDA (Pile Driving Analyzer) is a dynamic load testing equipment that is used for high-strain non-destructive load test method which can be done during or after installation of the pile. Pile Driving Analyzer systems also evaluate shaft integrity, driving stresses, and hammer energy when monitoring installation. This test can be applied to driven steel, driven timber and even concrete piles.
PDA gear figures the velocity and force signals acquired from accelerometers and strain transducers appended to the pile during driving. The CAPWAP software is used to compute the pile load capacity.
PDA testing can be attempted during beginning of driving or during re-strike drives after permitting soil setup on the pile for an appropriate time frame. PDA testing is attempted in conformance with ASTM Standard D4945-12.
By using the PDA test method we can directly save pile foundation materials and related establishment costs. The information that PDA testing can provide includes: Verification of pile capacity at the time of testing. Data for developing termination criteria for design loads. Assessment of energy transfer and driving efficiency. Measurement of stress levels induced on the pile during driving. Assessment of pile integrity and possible damage There are three basic types of PDA tests on driven piles:
- testing of a pile for the full installation.
- testing of a pile at end of initial drive (EOID).
- testing of the pile several days after initial drive.
Case Wave Analysis Program (CAPWAP)
Analysis PDA tests just give guide estimations to the forces and movements at the pile head. Movement over the heap shaft and toe and the static and dynamic soil parameters and dissemination of forces & are not directly estimated. To check the static part of pile resistance, CAPWAP examination is performed on field information from a chosen hammer blow from the PDA test record. CAPWAP examination settle three questions: Inside pile forcesPile movements and External forces.
By an iterative process in the CAPWAP software it can estimate and evaluate to polot a processed wave reaction of soil parameters and pile shaft and toe resistance dispersions. The procedure is repeated until the point that a sensible match is accomplished between the CAPWAP wave curve and with the measured wave reaction from the field information. The last CAPWAP result gives a “corrected” resistance result for the pile, the pile shaft and the pile tip. To guarantee that the last outcomes make sense in terms of accessible soil and groundwater data for the site so lot of judgement has to be applied during the CAPWAP investigation.