The Importance of Testing Installed Screw Piles and Bored Piles

Any quality construction project should be founded on sound engineering principles and engineer-led design. However, it is important to not become complacent, even when you have partnered with reliable contractors. The best contractors will provide advice on the need to continue to monitor the structure’s integrity.

There is always a requirement for ongoing monitoring after something has been constructed or installed. Forces outside of the blueprint can always act upon the structure and influence its integrity. Fortunately, with monitoring and maintenance carried out during and after installation, any emerging changes or risks can be nipped in the bud and dealt with promptly and effectively.

This unpredictable element is particularly true of a structure’s foundation – the point at which it ‘meets’ the less predictable, less controllable surface of the earth. The earth is prone to many forces such as compression, settling, and erosion, and piles serving as a foundation may be subject to below-the-surface sound waves and pressure.

The foundation is also subject to the weight of the structure above. This obviously applies downward weight on the structure, but the pressures can also be lateral, for example, due to wind. With such forces acting upon a structure and its foundation, due diligence should be built into any construction project life cycle, including well after the ribbon is cut and the structure opened to use.

Dynamic load testing

Dynamic load testing involves applying a dynamic load to a pile head to assess the pile’s bearing capacity in situ. This means that the pile has first been installed in place and this final check is taking place. Dynamic here means ‘changing’ or ‘altering’. It often involves applying repetitive blows at the pile head to monitor performance.

When the dynamic load is applied, the strain and acceleration of the pile are measured to determine how the pile will behave under strain and weight bearing; and to see whether the pile concrete is capable of enduring the stresses that are placed upon it. Sensors are often applied during the process and will assess the compressive waves travelling down the pile and up again.

Measurement of these factors can gauge the interaction between the pile and the soil, and support calculations of pile axial capacity. Dynamic load testing is often an affordable and effective method to employ, and requires less additional resources to carry out, when compared to static load testing. It may therefore be appropriate for sites with limited space and offshore projects.

Static load testing

This type of test is used by your NSW piling contractor when installing screw piles to determine, in practice, whether they will be capable of supporting the structure. It involves applying a load gradually, and in this way, it mimics what will occur in real life when the structure is installed, and the pile used to support it. This tests not only the pile, but the response of the surface. Static load testing allows assumptions to be replaced with evidence-based decision making. During the application of load, displacement is measured.

Because it is a slow and precise process that reflects what will occur in real life when the structure is placed under strain, this method is often valued for the accuracy of its results when it comes to assessing pile bearing capabilities, settlement, and pile uplift. The results can be checked against and correct assumptions and may sometimes help to redefine the design and its parameters. Static load testing of piles is also valued for being appropriate to many soil types, and the fact it can also assess how piles behave under tension or lateral pressure.

However static load testing can be a complex job that involves significant weights and the transport thereof. Sufficient space must be available on-site to carry out the load testing. It has an associated cost that can be discussed and quoted openly with a quality screw piling contractor in Sydney. The most accurate picture may be formed if both static and dynamic tests are used in conjunction. Your screw piling contractor such as Piling Experts will be happy to discuss options with you.

Pile Integrity Testing of bored piles

Pile integrity testing (sometimes also referred to as a low strain dynamic test or sonic echo test) is a vital step in quality control for cast in place or precast concrete. It is capable of detecting structural defects such as cracks or cross-section changes due to installation errors. Its purpose is to discover flaws in a timely manner so that they can be dealt with effectively before the need for more costly restoration works arises or the risk profile is compromised. The methods used in a pile integrity test are complex and varied. They may involve pulse echo or transient dynamic response technology and can produce information on pile length, head stiffness, and shaft mobility.

We encourage you to get in touch with The Piling Experts for more information about pile testing on 0411 693 100 or info@pilingexperts.com.au.