Results from additional dynamic cone penetration testing of soils on the Utuado Batholith, upland and dissected terrains, Puerto Rico - June 2022

A Smart Dynamic Cone Penetrometer (DCP) system allows for the partially automated collection of cone penetrometer data (CPT) to determine mechanical properties of soil along a vertical profile. A smart DCP system was used to collect soil penetration-with-depth values alongside 12 soil pits dug in the Utuado Batholith, a late Cretaceous age granodiorite pluton located on the northern portion of the Cordillera Central in west-central Puerto Rico (Learned et al., 1981). Both the upland plateau (PL sites) and steep dissected terrain, or side slopes (SS sites), of the Utuado batholith were tested. The data is used in the associated publication on soil and saprolite mineralogy and geochemistry (Ryan et al., in review).
 
Field testing and result calculation was conducted in accordance with ASTM standard D6951/D6951M-18, Standard Test Method for Use of the Dynamic Cone Penetrometer in Shallow Pavement Applications, in order to assess in situ strength of undisturbed soils (ASTM International, 2018). Upon selection of testing location and assembly of the DCP system, a penetrating rod was driven into the soil using a standard weight (4.6 kg) dropped from a consistent height (575 mm) (Applied Research Associates, 2022). Data were automatically captured and recorded on the Vertek Smart DCP application, including the number of blows, the change in depth per blow, and the total depth achieved, which are used to determine the California Bearing Ratio (CBR) percentages (Al-Refeai and Al-Suhaibani, 1997). Changes in the CBR percentage can be used to identify thickness of soil horizons and depths of near surface contacts and estimate other material characteristics at specific depths.
 
The Results_June2022 file includes columns which list the tested site’s name, the cumulative depth of penetration by the rod tip into the soil in millimeters, and the CBR (%) which is calculated during sampling internally by the Vertek Smart DCP application. Each row represents one blow of the hammer and the resulting values. If the equipment malfunctioned in the field, the error was noted and the data was manually corrected during pre-processing. This is captured in two additional columns in the Results_June2022 file which list the corrected cumulative depth in millimeters (as necessary) and notes on the blow during which the error occurred. If no correction was needed, the “Corrected Depth (mm)” and “Depth (mm)” columns are identical. The Locations_June2022 file includes a name column, which corresponds to the testing site names within the Results_June2022 file, the test date, and corresponding latitude and longitude columns.
Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government

References:
 
Al-Refeai, T.O., and Al-Suhaibani, A.M., 1997, Prediction of CBR using Dynamic Cone Penetrometer: Journal of King Saud University: Engineering Sciences, v. 9, p. 191-203, https://doi.org/10.1016/S1018-3639(18)30676-7.
Applied Research Associates, 2022, SmartDCP User Guide (DOC-0073), Rev.3.0, October 2022: Vertek Division of Applied Research Associates Inc., Randolph, Vermont.

ASTM International, 2018, Standard Test Method for Use of the Dynamic Cone Penetrometer in Shallow Pavement Applications, ASTM D6951/D6951M-18: ASTM International, https://www.astm.org/d6951_d6951m-18.html.

Learned, R.E., Hickey, T.H., and Perez de Gonzales, I., 1981, A geochemical reconnaissance of the Utuado Batholith and vicinity, Puerto Rico: U.S. Geological Survey Open-File Report 81-1131, 5 p., https://doi.org/10.3133/ofr811131.