Wednesday
Oct252017

Leading Thoughts: 10/25/17 Pump Up the Footing Bearing Pressure

Why build a large structure on low bearing pressure footings?  It’s inefficient, costly, and consumes more energy and more of your schedule.  It also brings a feeling of defeatism right away to the project team (okay maybe that is going a bit far!)

We know that Geopier Rammed Aggregate Pier® is many times stiffer than the surrounding soils, especially when the soils are soft.  We have university and peer-reviewed studies and thousands of load tests to prove it.

One of the fringe benefits of this stiffness, besides settlement control, is the potential for high bearing pressures.

Your structural engineer smiles when he sees a high allowable bearing pressure.  And why not?  He can size smaller footings with less reinforcing steel.  The General Contractor can build the footings more quickly and with less cost.  The Owner can spend the savings on things they can actually see!  Like jewelry, fixtures, larger conference table, upgraded golf clubs, etc.

  

Example Project

We recently finished a project in Ames, Iowa with heavy column loads (up to 2,000 kips) over moderately stiff glacial clay till.  Due to settlement control issues the Geotechnical Engineer could not provide a practical design bearing pressure.

Enter Geopier and Ground Improvement Engineering.  We were able to stiffen these soils using the Geopier GP3® system for a bearing pressure of 8,000 pounds per square foot.  That allowed for reasonable footing sizes.  We also controlled settlements to 1-inch. 

We performed modulus load testing to confirm the pier stiffness.  The test imposed a load of 155 kips on a single 30-inch diameter Geopier element; the deflection was less than ½-inch.  Now that is performance!

 

Final Thoughts

You shouldn’t have to settle for a low foundation bearing pressure when your loads are heavy. Give us a call whether you have soft clay, fill, loose sand or peat and organic silt.  We will listen and develop a tailored Geopier solution.

And you can take the savings to the bank. 

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