Pile Driving Monitoring (PDM) during driving and Pile Dynamic Testing (PDT) are widely used in onshore and offshore construction to ensure the structural integrity of the piles during driving and achieve a safe and economical pile installation. PDM helps to assess the pile behaviour during installation and thus to confirm the assumptions taken during pile design; as well, it allows to control the dynamic stresses in the pile and keep the hammer energy at max level compatible with pile integrity, thus allowing for an efficient management of the piling on field. As well, it ensures that driving follows the established criterion, providing key elements for calculating the soil resistance at the time of monitoring and on driving system performance.
Pile Driving Monitoring involves attaching strain gauges and accelerometers to the top of the pile. The striking of the pile with the hammer generates stress and velocity waves which travel along the pile and mobilise the shaft friction and the base pile capacity; upward waves are thus generated which travel towards the pile head; such waves are recorded and analysed to determine the actual hammer energy transferred to the pile, pile’s ultimate bearing capacity and the soil resistance under continuous driving conditions.
PDM is the only way to evaluate the stresses induced anywhere in the pile during driving and the results can be used to confirm the static axial pile capacity which is especially important where there is a risk of premature driving refusal or of encountering challenging geological conditions. PDM results can be used to validate the assumptions made during the pile design and for installation assessment. This has resulted in cost savings in terms of pile length and associated installation timescales.
In short, PDM helps to –
- Establish pile ultimate bearing capacity and confirm pile design assumptions,
- with the PDT, avoid expensive pile static load testing,
- Assess and manage the risk of pile tip buckling,
- Allow development of pile driving prediction numerical models,
- Evaluate pile fatigue resulting from driving process, and
- Permit the development of a model to facilitate back analysis of non-instrumented piles.
With a large experience in pile installation supervision and monitoring, G-Octopus, a Cathie Company, has capabilities in both onshore and offshore fields, above water and under water pile driving monitoring and testing. G-Octopus has extensive experience of PDM and PDT within the oil and gas sector and more recently, in offshore wind power, and provide advanced interpretation and analysis of the pile driving monitoring data. G-Octopus operate the Pile Driving Analyser (PDA) and PAX acquisition units manufactured by PDI, which are widely regarded as the most reliable systems in the market. The PDA acquisition units are deployed in conjunction with PDI manufactured strain gauges and accelerometers, and the data captured is analysed using the latest versions of GRL WEAP, PDA-W and CAPWAP. Our engineers are familiar with the offshore environment and trained to liaise with barge masters and deck foreman to minimise interference with the installation schedule. G-Octopus has provided PDM services to projects such as Bokum West II, North sea, Gwynt Y Mor, Irish Sea and AGM-N Platform, Anguille Redevelopment.
G-Octopus and Pile Dynamics, Inc are now organising a seminar and training event in Paris this May to explain the basic concepts of various field testing applications, the advantages and limitations of various integrity and capacity methods in assessing bored piles and choosing the appropriate methods for analysis. This one-day seminar is suitable for those in the field of deep foundation testing and analysis, and includes an overview of recent advances in non-destructive testing methods of bored piles and driven piles.
Click here to learn more about the event.