CPT sounding and the scale of variability of Auckland residual soil

Abstract

The cone penetration test (CPT) provides a huge amount of data in comparison with other in situ test procedures - complete sets of readings every 10 mm or so of penetration. Some years ago a site in Albany was investigated with 30 closely spaced CPT soundings to a depth of 10 m. The intention of this paper is to take the analysis of the data gathered further in order to understand better the scale of the variability of the properties of the residual soil common around the Auckland region. We have data at two scales: vertical and horizontal. In the vertical direction, there are one thousand readings over the 10 m depth of each sounding. In the horizontal direction, there are 30 CPT soundings within a square of 8 m side, the closest being at 1 m spacing. We will present our explorations of the properties in terms of an autocorrelation function and by determining the average distance between zero crossings of the de-trended qc data.