Professor, North Carolina State University, Raleigh, NC
Project engineer, NCSU, Subsurface Inc., RaleighNC,
Adjunct associate professor, North Carolina State University, Raleigh, NC
(Received 11 November 1999; accepted 27 November 2000)
The potential use of the Dynamic Cone Penetrometer (DCP) as a compaction quality control tool is investigated in this study. The DCP is a simple device and relatively inexpensive to operate. Results from a laboratory testing program performed on three piedmont residual soils with appreciable fine content (> 60%) yielded correlation patterns for the estimation of moisture content (w) and dry unit weight (γdry), based on the DCP penetration rate (PR). The PR-liquidity index (LI) data were best correlated with an equation in the form of LI = A Log PR-Bm. For the test soils, A was equal to 0.65 and Bm = 1.2. On the other hand, the PR-degree of saturation (S) data were best correlated with the equation in the form of S = 1 − eCm*PR with the Cm coefficient estimated equal to −0.065. Using the principles of soil mechanics, w and γdry are calculated based on the predicted LI and S values, respectively. Using the water content and unit weight models, and on the average, the water content was underpredicted by 0.2% and the dry unit weight was overpredicted by 0.3 kN/m3. The developed model parameters are expected to vary for different soil types as well as compaction effort and a field calibration procedure in which moisture contents and dry densities are evaluated by alternative means, on a limited scale, is recommended.
Paper ID: GTJ11349J