Dynamic Load Testing
Table of Contents
Last updated
20 May 2025
What is Dynamic Load Testing?
Dynamic load testing, or dynamic testing, is a method of pile testing. It assesses the load-bearing capacity of a pile by applying short-duration, high-intensity loads. This is typically done by striking the pile with a hammer, while sensors measure the resulting forces and displacements. The data collected is then analysed using signal-matching software to estimate the pile’s bearing capacity, integrity, and resistance distribution.
Unlike static load testing, which requires prolonged loading over time, dynamic testing offers rapid insight into how a pile will perform under actual working conditions. It is particularly suited to driven piles but can also be applied to bored and CFA (continuous flight auger) piles with temporary preparation.
Common Uses
Dynamic load testing is widely used in various sectors of construction and infrastructure, including:
- Highway and railway projects – to validate foundation design under tight time constraints.
- Marine and offshore structures – to assess pile capacity where traditional static testing is difficult or impossible.
- Urban developments – where limited space or environmental constraints make dynamic testing a more viable option.
- Wind turbine foundations – where efficiency and scalability are essential across large sites.
- Bridges and retaining walls – for fast, reliable feedback on pile performance.
In short, any project requiring quick and accurate assessment of pile performance, particularly where large numbers of piles are involved, can benefit from dynamic load testing.
Process
The process of dynamic testing generally involves [1]:
- Pile Preparation – Before testing begins, piles are instrumented with strain gauges and accelerometers. A PDA (Pile Driving Analyser) is connected to the sensors and records the data from the test.
- Impact Loading – A drop hammer or driving rig applies a controlled impact to the pile head. The resulting stress wave travels down the pile and reflects back. This wave behaviour provides valuable data on the pile’s resistance.
- Data Collection – The sensors record force and velocity during each impact. Several blows are typically applied to ensure consistent and reliable readings.
- Analysis – The collected data is processed using signal-matching software (like CAPWAP) to calculate ultimate pile capacity, resistance distribution, and dynamic response characteristics.
- Reporting – A detailed report is compiled by engineers to summarise the test results, which can be used to verify design assumptions and inform further geotechnical decisions.
Advantages
The advantages of dynamic load testing include:
- Suitable for all pile types
- Can be completed in a matter of hours, allowing for real-time decision-making and reduced downtime on-site
- Compared to static testing, dynamic testing requires less equipment, fewer materials, and reduced site disruption, resulting in significant cost savings
- The equipment used is compact and mobile, making it ideal for sites with restricted access or challenging terrain
- When conducted by experienced professionals, it provides highly accurate estimates of pile capacity and performance under working loads
- Since the test involves relatively short, sharp loading, it has a lower environmental impact and avoids prolonged stress on the foundation or surrounding structures
- Results from dynamic load tests help verify design assumptions, optimise pile lengths, and reduce the risk of over-designing, ultimately saving materials and time
An Example of Dynamic Testing
From March to April 2016, Aarsleff was awarded the ground engineering contract on behalf of main contractor Carillion to provide the driven piling foundations to support the main buildings of Hampton Gardens Secondary School in Peterborough.
Using its own Banut 700, Aarsleff installed 323no 250/300mm square precast concrete piles of 16m driven into very stiff ground. Due to the hard clay and the majority of made ground consisting of Pulverised Fuel Ash Fill (PFA), Aarsleff carried out dynamic load tests before commencing with main piling works in order to take into account the negative skin friction in regards to pile capacity.
Written by Aarsleff UK
20 May 2025
Aarsleff Ground Engineering is a leading sheet piling supplier and contractor. We specialise in designing and delivering sheet piling solutions across the UK.
Reviewed by Mark Fuller, Piling Director
20 May 2025
Mark Fuller is the Piling Director at Aarsleff Ground Engineering. He has amassed a wealth of experience and knowledge within the specialist piling and ground engineering industry throughout his 20 years of experience in the industry. Mark is directly responsible for the overall driven piling within the business, including technical and operational management of awarded contracts, development of strategic long-term plans and planning of recruitment and resource.
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