Portable penetrometer correlation with STP 1

[racwa]

I'm seeking a correlation between portable penetrometer (specifically, a Porta-Pen) and standard penetration testing. The CPT-SPT correlation is not applicable. I've requested the 1966 G.F. Sowers paper from ASTM Special Technical Publication 399. Does anyone know of any other resources? Thank you.

 

[MRM]

There is a post under the "Soil Testing Engineering" forum entitlied "Mackintosh vs. SPT vs. CPT tests." This thread has some discussion related to what you are asking. This may be a start.

 

[earthshake]

As I recall, George Sowers developed the dynamic cone penetrometer (DCP) test while working as an engineer for Law Engineering and serving as a professor at Georgia Tech. The SPT correlations that are provided with the DCP equipment are likely related to his work in Piedmont residual soils encountered through much of Georgia and the Carolinas and further up the east coast. It is reasonable to expect that similar correlations could be developed in other geologic settings. According to Sowers, the DCP is suited for construction control and field exploration for lightweight structures. In general, the penetrometer produces the best correlations between 4 and 30 blows. Below 4 blows, for the required 1-3/4 inch penetration increment, the soils are too soft or loose to produce significant results. Above 30 blows per penetration increment the correlations are quite variable.

The DCP does not work well below the water table unless the borehole is stabilized to prevent inflow and soil softening. The DCP is of limited use in evaluating alluvial soils of Piedmont or Blue Ridge origin (which includes the Upstate of South Carolina and western North Carolina) in that the calibration ratios vary without specific pattern.

 

[Focht3]

Use the correlations carefully, lest they get you into trouble. And don't rely too much on any mechanical cone, particularly the hand held ones -



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