## 4 Application of APD to Other Sites
### Oysand Site  
The Oysand test site is located approximately 15 km southwest of Trondheim, Norway. Site characterisation at the Oysand research facility began in 2016 as part of the NGTS project. Since then, a wide range of in situ tests, geophysical surveys, sampling techniques, and laboratory investigations have been conducted to assess the geological history and geotechnical properties of the sand deposits [58].  
The CPT results used as input for APD, along with the associated methods and additional details about the Oysand site, are provided in [59]. A comparison between the results generated by APD and the reference values interpreted for this site is shown in Figure 6. The results are presented for the sand layer (between 12 and 18 m).  
The total unit weight was indirectly determined from water content measurements of the samples, assuming full saturation [58]. However, the water content measurements from disturbed samples were found to be lower than expected, likely due to sample disturbance [60]. Water migration during sampling, transportation, and storage can lead to such discrepancies [60]. As a result, the actual in situ unit weight is expected to be lower than the reported values. The results obtained from the CPT-based workflow are shown in Figure 6a. Overall, the methods tend to underestimate the reported values; however, considering that these reference values are based on disturbed samples, lower in situ values are anticipated.  
Five isotropically consolidated triaxial tests--three undrained (IUC) and two drained (IDC)--were performed on undisturbed (frozen) samples collected at depths of 13.3, 13.8, 14.1, 14.3, and 14.6 m [60]. Accordingly, five reference values are reported for \(e_{0}\), \(D_{r}\), and \(\varphi^{\prime}_{p}\), as highlighted in Figure 6b-d. Figure 6b presents the values obtained from the CPT-based workflow, using the unit weights shown in Figure 6a as input.  
The reference relative density values are significantly influenced by the method used to determine \(e_{min}\) and \(e_{max}\) in the laboratory [60]. The values obtained from the CPT-based workflow are presented in Figure 6c. As shown in the figure, the upper bound of the range successfully captures the first three reference values, while the lower bound captures the two lower reference values. On average, the CPT-based methods underestimate the first three reference values and overestimate the last two. The peak friction angles were determined from three undrained isotropically consolidated (IUC) and two drained isotropically consolidated (IDC) triaxial tests, as highlighted in Figure 6d. With the exception of the fourth reference value (at a depth of 14.3 m), the methods predict the peak friction angles reasonably well. The reference values for the shear wave velocity were derived from the seismic SCPT20 (OYSC20 in the project) test. As shown in Figure 6e, the CPT-based workflow provides a reasonable prediction of the in situ \(V_{s}\) values.  
Figure 5: Comparison between APD and interpreted values at Halden silt test site: (**a**) unit weight, (**b**) constrained modulus, (**c**) small-strain stiffness, (**d**) undrained shear strength (modified from [6]).