The dynamic analysis of pile driving, commonly known as dynamic load testing (PDA testing), is a quick way to assess the mobilized static bearing capacity, the stresses in steel, the integrity of a pile and the driving energy, given by the pile driver, using a dynamic strain (impact). All of this is available for a fraction of the cost and time required for conventional static load testing. Dynamic load testing is conducted according to the ASTM D 4945 standard “High-Strain Dynamic Testing of Deep Foundations,” currently in effect.
Dynamic load testing can be conducted on several types of piles. In Quebec, tests are most commonly carried out on tubular steel pipe piles and on HP piles. Testing can also be done on other types of piles, including bored piles – whether or not they are embedded in rock, wooden piles, controlled rigidity columns (CRC), composite piles made of steel and concrete, and finally, caisson.
PDA CONSULTANTS INC. has also conducted dynamic load testing on less common types of foundations, such as GEWI piles and sheet piling. In addition to its use in new constructionprojects, dynamic load testing can be applied to existing piles in order to perform appraisals on deep foundations in place.
Dynamic load testing can be used in pre-project assessment in order to optimize the type of deep foundation to be used, pile length and cost of construction and an adequate pile driver equipment. Implementing a preliminary test program or continuous pile monitoring are both means of gathering important data for this optimization.
In addition, it is possible to calibrate the pile driver equipment by adjusting the energy measured with the pile driving analyzer to the energy indicated on the monitor inside some hydraulic driving equipment.
In addition, it is possible to calibrate the pile driver equipment by adjusting the energy measured with the pile driving analyzer to the energy indicated on the monitor inside some hydraulic driving equipment.
The use of the pile driving analyzer can also give rise to other targeted applications such as assessing the energy transmitted to a split corer (SPT) during exploratory drilling for geotechnical investigation. Measuring this energy using the pile driving analyzer allows for the adjustment of values obtained in the process according to the real energy transferred to N60 standardized values in compliance with the standard ASTM D-1586 « Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils » in effect.
Two types of analyses that are complementary to dynamic load testing of piles are also possible – the wave equation analysis with the help of the GLRWEAP software (Wave Equation Analysis Program) and the CAPWAP analysis (Case Pile Wave Analysis Program).
Wave Equation Analysis (WEAP) is used to evaluate the theoretical refusal criteria or criterion for pile driving and calculate the stresses in the piles. This analysis takes place based on the data gathered through the geotechnical investigation, the characteristics of the piles used, as well as the type of driving equipment planned for the site. This calculation, however, remains theoretical, and must be confirmed by dynamic load testing. Additionally, WEAP analyses make it possible to estimate the time required to drive a pile in order to optimize the driving equipment to be used on the construction site.
On the other hand, the CAPWAP analysis makes it possible to evaluate the total capacity of a pile as well as the distribution of the resistance along the pile shaft and at the pile toe. This analysis can be used to estimate the pull-out resistance of the pile following a dynamic load test.
PDA CONSULTANTS INC. engineers’ team offers other services such as Cross-hole Sonic Integrity testing and the supervision of deep foundations, training and consultation. Contact us today to benefit from our services.