## 3 Results and Discussion  
### Stress-Strain Variation in the Piles  
Stress distributions along the piles (BP# 1 and BP# 2) in two continuous loading/unloading cycles have been illustrated in Figures 11-14, showing that in a specified load, normal stress used in the pile's surface area is reduced by depth. Therefore, the reduction rate varied along with the pile--it is low in soft soil layers (having low SPT-N) but sharp in stiff layers (with high SPT-N). These results indicate great skin friction capacity of soil where rapid change between two different depths.  
[PERSON] et al. [41] have declared that the forecast of deep foundation settlements in a layered soil profile is not always straightforward due to the problems in value defining of mechanical parameters affecting them. Distribution of average change and their cycles, in both strains (BP# 1 & BP# 2), in addition to the distribution of back-calculated modulus of concrete as \(E_{c}\) (kN/mm\({}^{2}\)) in both strains (BP# 1 & BP# 2) are shown in Figures 15 and 16. In BP# 1, \(E_{c}\) for the entire length remained constant at 25 kN/mm\({}^{2}\) except at depths below 5 m within stiff sandy silt with little gravel when the higher load showed slightly lower \(E_{c}\) (Figure 15a). Therefore, the results obtained for \(E_{c}\) (in BP# 2) changed based on the depth and applied load. The lower applied stress through the first cycle provided minor changes in \(E_{c}\) distribution along the pile length. However, higher applied load amounts caused a higher change in \(E_{c}\) with depth (Figure 15). The highest and lowest \(E_{c}\) for the depth = 17.816 m (in BP# 2) were 38.2 and 33.9 kN/mm\({}^{2}\), resepectively, for the applied stress of 1,750 kPa and 12,904 kPa. The reverse relation of \(E_{c}\) with applied stress occurred when higher applied stress on the pile cap showed lower \(E_{c}\) (Figure 16a). Consequently, the highest variation in \(E_{c}\) was observed within the silty and/or sandy silt layers, while the lowest change in \(E_{c}\) was measured at the weathered sandstone zone at depths above 20 m (Figure 16b).  
Figure 10: Existing platform in full-scale maintenance of the pile load test.  
Figure 11: Stress distribution measured along BP# 1 in (**a**) 1 st cycle and (**b**) 2 nd cycle.  
Figure 12: Stress distribution measured along BP# 2 in (**a**) 1 st cycle and (**b**) 2 nd cycle.  
Figure 13: Distribution of average change in strain measured along BP# 1 in (**a**) 1 st cycle and (**b**) 2 nd cycle.  
Figure 14: Distribution of average change in strain measured along BP# 2 in (**a**) 1 st cycle and (**b**) 2 nd cycle.  
Figure 15: Distribution of back-calculated elastic modulus of concrete, \(E_{c}\) (kN/mm\({}^{2}\)) for BP# 1; (**a**) 1 st cycle and (**b**) 2 nd cycle.  
Figure 16: Distribution of back-calculated elastic modulus of concrete, \(E_{c}\) (kN/mm\({}^{2}\)) for BP# 2; (**a**) 1 st cycle and (**b**) 2 nd cycle.  
Average SPT-N and unit skin friction in BP# 1 & BP# 2 presented in Figure 17, indicate the range of ultimate skin friction with value change of SPT-N. Furthermore, in multilayer site conditions, the least SPT-N sum for a soil layer provided the least unit skin friction and vice versa. The outcome derived from GSE sensors was computed according to the displacement amounts recorded by the sensors. A higher alteration for the recorded axial force within two continuous levels provided a larger unit skin friction for a specified soil layer (Figure 17).