Comparison of a Dynamic and Static Penetrometer for Reproducibility of Readings.
Eric Brevik, Dept of Physics, Astron, and Geosciences, Valdosta State Univ, Valdosta, GA 31698-0055
Two penetrometers, one dynamic and one static, were compared to see which had the most reproducible readings. To make this comparison, 21 undergraduate students were divided into three groups of seven. The students were given instructions on use of the penetrometers. Each group was then sent to seven stations to take penetrometer readings. The readings for each station from each group were averaged and the mean values for each group at each station were compared using t-tests. The standard deviations for each penetrometer as a percent of the mean penetrometer values were also calculated to see which penetrometer (dynamic or static) produced more consistent results. This study found that 18 of the 21 dynamic penetrometer mean comparisons were not statistically different, while 14 of the 21 static penetrometer mean comparisons were not statistically different. The average dynamic penetrometer standard deviation was 18.7% of the mean penetrometer values, with a low of 5.5% and a high of 54.3%. The average static penetrometer standard deviation was 56.4% of the mean penetrometer values, with a low of 21.7% and a high of 264.6%. These results were interpreted as indicating that the dynamic penetrometer gave more consistent, reproducible results when compared to the static penetrometer.