Characterization of the correlation structure of residual CPT profiles in sand deposits

Among the different ways of in-situ soil investigation, cone penetration test data are selected to evaluate the spatial variability of geomaterials and the scale of fluctuations is chosen to evaluate the correlation structure of CPT data. In this regard six case studies in sandy materials from Australia, U.S.A. and Iraq are selected. Various techniques for the calculation of the scale of fluctuation of geotechnical parameters are suggested in literature e.g. VXP, SAI, AMF, BLM and VRF without any preference or privilege for any specific procedure. In order to isolate the stochastic portion of cone tip resistance, deterministic trend was first removed by regression analysis. This study suggests that quadratic trend removal is more suitable for selected CPT data soundings. The closeness of the estimated scale of fluctuation using different approaches is assessed too. Mean value of the scale of fluctuation by five established methods ranges between 0.44 to 1.52 meter for six different cases and the coefficient of variation for the scale of fluctuation calculated by these methods varies between 12 to 27 % showing that available established methods produce almost compatible and comparable results.