There is no correlation between our DCP and the “N” value.
The “N” value is determined from the STP (Standard Penetration Test). That test is widely used for deep foundation work. A drill rig is used to drop a 140 lb hammer driving a split spoon sampler. The N value can then be used to determine the bearing capacity in psf (pounds per square foot).
Because many of the foundation equations used by engineers use the “N” value we have had similar requests for a correlation from the DCP penetration rate to the “N” value. I have surfaced this with the Corps of Engineers (who own the patent for our DCP) and they (Jeb Tingle PhD, P.E. overseer of the DCP technology) has said because they have provided a correlation to psf there is no need to have a correlation to the “N” value. If however someone wants to pay them to do the research to get a correlation from the DCP penetration rate to the “N” value, they would take this project on.
By the way, we sell the Sower’s DCP which does have a correlation from the penetration rate to an N value. Developed years ago by George Sowers at Georgia Tech for Piedmont Soils, it is very popular but much more difficult to use than our K100 DCPs. One must auger to the depth to be tested and then drive the point down 2 inches. This process can be repeated to a depth of about 11 feet.