There has been recent increased use of augered cast-in-place (ACIP) and drilled displacement (DD) piles in the foundations of buildings and transportation structures. In the article “Design Methodology for Axially Loaded Auger Cast-in-Place and Drilled Displacement Piles” (J. of Geotech. Geoenviron. Engr., 2012: 1431-1441), researchers propose a design methodology to enhance the efficiency of these piles. Here are length-diameter ratio measurements based on 17 static pile load tests on
ACIP and DD piles from various construction sites. The values of for which percentiles are needed are and .971 .
| ( x_{(i)} ) | 30.86 | 37.68 | 39.04 | 42.78 | 42.89 | 42.89 | 45.05 | 47.08 | 47.08 |
|---|---|---|---|---|---|---|---|---|---|
| ( z ) percentile | -1.89 | -1.35 | -1.05 | -0.82 | -0.63 | -0.46 | -0.30 | -0.15 | 0.00 |
| ( x_{(i)} ) | 48.79 | 48.79 | 52.56 | 52.56 | 54.80 | 55.17 | 56.31 | 59.94 | |
|---|---|---|---|---|---|---|---|---|---|
| ( z ) percentile | 0.15 | 0.30 | 0.46 | 0.63 | 0.82 | 1.05 | 1.35 | 1.89 |
Figure 4.35 shows the corresponding normal probability plot generated by the R software package. The pattern in the plot is quite straight, indicating it is plausible that the population distribution of length-diameter ratio is normal.
Figure 4.35
Normal probability plot from for the Length-Diameter Ratio data
