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Sometimes a Second Opinion From a Trusted Geotechnical Expert Is Exactly What Your Project Budget Needs

11.11.15   Robert C. Rabeler, PE | More by this Author

Sometimes a Second Opinion From a Trusted Geotechnical Expert Is Exactly What Your Project Budget Needs

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 contacted to provide a second opinion regarding foundation support for a large printing facility. Another firm had recommended expensive drilled shafts (caissons) for foundation support. To develop a more cost effective solution, SME’s geotechnical experts performed pressuremeter tests to more accurately evaluate the soil conditions at the site.

Pressuremeter tests are performed by inserting a special probe in a conventional borehole. Incremental loads are applied to the soil using gas and water pressure, while recording incremental deformation measurements. The resulting deformation vs. load data is evaluated to obtain the pressuremeter modulus and limit pressure. The pressuremeter data is then used to more accurately predict foundation settlement and bearing capacity, compared to conventional methods using split spoon blow counts. This more accurate analysis has routinely allowed SME to provide higher design soil bearing pressures for foundations, resulting in smaller footing sizes and associated savings in construction costs.  SME’s geotechnical experts recommended that the owner place a surcharge load on the site, allowing the soil to compress for two to three months. SME measured the resulting settlement and confirmed that this building could use normal spread footings, saving the owner over $100,000 – a return on investment of at least 17:1!

For more information contact Bob Rabeler.


TAGS: Geotechnical

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