A Comparison of the Sowers Dynamic Cone Penetrometer Test with Cone Penetration and Flat Blade Dilatometer Testing

The Sowers dynamic cone penetrometer (DCP) has been used as a relatively low-cost near-surface soil investigation tool in the Southeastern United States for over 40 years. Typically, the Sowers DCP penetration resistance has been correlated to standard penetration test (SPT) N values for use in geotechnical analyses such as bearing capacity evaluation. Published correlations of DCP and SPT penetration resistances are limited to Piedmont residual soils in and around Atlanta, Georgia and soils in Idaho, Utah, and Wyoming. Correlations of Sowers DCP test results to piezocone penetration test (CPTu) and flat blade dilatometer test (DMT) measurements have not been examined. The following paper examines correlations between the Sowers DCP penetration resistance (n), corrected tip resistance (qt) from piezocone penetration testing, and dilatometer modulus (ED) from flat blade dilatometer testing in lower Atlantic Coastal Plain soils. Testing data were collected from eight sites in the Charleston, SC area. Correlations were conducted taking into account soil classification and groundwater location. Analysis of the data showed no clear correlations exist between these three test measurements with the exception of a linear relationship between n and qt for silty sands below the groundwater table, where a relationship of qt,ave(MPa)/n approx. 0.5 was observed regardless of classification method.