Working with a Trusted Geotechnical Engineer Can Save Your Project Budget and Schedule


Working with a Trusted Geotechnical Engineer Can Save Your Project Budget and Schedule

This article is part of a series regarding lessons learned in geotechnical engineering. These are real projects with real people, but the names have been omitted to protect those involved.

SME was retained to provide geotechnical engineering services for a Corporate Campus project. The site was located over an ancient glacial sluiceway that was later filled with loose sediment including organic deposits. Deep foundations would be the only way to support this structure. Based on preliminary borings performed by another firm, pipe piles were proposed for foundation support. However, none of the preliminary borings extended deep enough to properly evaluate deep foundations.

SME performed additional soil borings and found the loose and compressible soils extended to a depth of about 120 to 130 feet below grade. SME recommended switching to H-pile type deep foundations. Instead of providing for one pile capacity for the project as is normally done, SME provided several working capacities based on different pile lengths.

Working closely with the contractor and the structural engineer designing the foundations system, SME was able to help optimize the foundation design. Making changes to the initial pile design saved $334,000 – six times SME’s design fee for the project!

To confirm the foundation design, pile load tests were performed. During driving of the test pile, SME used its Piles Driving Analyzer (PDA) to evaluate driving conditions and pile capacity. The load test confirmed SME’s design recommendation.

During installation of the piles, some misaligned piles were found, and requests were made to drive them an additional 10 feet to accommodate increased structural load. However, SME anticipated that the piling may be capable of supporting additional loads. Working with the piling contractor to re-strike the piles, SME’s geotechnical experts were able to show that no additional driving was necessary. This engineering evaluation by SME saved the project schedule and kept the project within budget.

Also during pile installation, the contractor reported difficulty driving some of the piles to the required depth. SME provided PDA testing of some piles, which showed pile capacities on re-striking exceeded the required capacity. SME was able to show no additional driving was necessary to meet the requested pile capacities. Again, SME’s geotechnical experts saved the project schedule and budget.

For more information, contact Bob Rabeler, PE.

TAGS: Geotechnical

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