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Driven Pile Foundation Testing and Optimization

“Right sizing” your driven pile foundations is key to achieving the lowest total project cost while maintaining compliance with applicable building codes and safety factors. The steel piles can be a significant cost to the project and failure can lead to tilting arrays, binding of tracking systems, or even posts that heave or pull out of the ground.

The traditional method is to use a general geotechnical site investigation, test a selection of random piles to confirm soil properties, and calculate the embedment depth to account generally for the forces required by the racking manufacturer. Often, each step is performed by a different company with safety factors applied at each step. Problems have occurred with an incomplete allowance for a variety of factors such as snow load, soil variability, groundwater, adfreeze, soil corrosivity, and frost heave. Overly conservative designs can cost a project millions in additional cost, while insufficient post length can lead to increased O&M costs, reduced production, and array failure.

RRC employs an exhaustive multi-disciplinary approach, beginning with a careful geotechnical sampling and analysis to understand not only soil type and properties but also variability across the site. The results are then discussed with the structural engineering team and several foundation solutions are developed, along with an anticipated design window to use for on-site pile load testing. This takes a wide variety of variables into account. Next, we strategically select the test sites with emphasis on developing data that will be most representative. The potential for different designs for different areas and soil conditions is considered. As the piles are driven and tested, considerable data is collected to correlate the soil types and tested parameters to the actual load capacity, leading to the optimal sizing and embedment depth for the array. Driving data can also be used to develop an appropriate QC window for use during production installation, which further ensures that the final installed piles will meet the required load capacity. The resulting designs minimize excess steel, while meeting code and the requirements for the foundation.

The traditional approach is typically carried out stepwise. When carried out by different companies, each awaits the final report from the previous step to begin work. With RRC responsible for all phases, concurrent engineering can often save weeks on the project schedule compared to a traditional linear approach. With our foundation optimization service, right-sized driven pile foundations minimize total project cost and decrease project risk.