# Model Tests on Jacked Pile Penetration Characteristics Considering a Static Press-in Piling Machine
## 3 Test Results and Analysis
### Pile Jacking Resistance  
Figure 8 depicts the analysis of pile jacking resistance in the two groups of tests. The pile jacking resistance comprises mainly the pile end resistance and the side friction resistance. Analyzing Figure 8, it is evident that the pile end resistance and pile side resistance in both groups of tests increase with the depth of pile jacking, with the pile end resistance being significantly greater than the pile side resistance. However, when the pile sinking depth is within 10 cm, both tests of piles exhibit a linear increase in end resistance with the growing depth of pile penetration and the total side frictional resistance remains minimal. As the pile sinking depth exceeds 10 cm, the increase rate in end resistance significantly diminished, while the side friction resistance begins to escalate. Moreover, the resistance of the sinking pile in test PS2 is notably greater than that of test PS1 at equivalent sinking depths. Specifically, at the conclusion of the pile driving process, PS2 demonstrated  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Test Number** & **Pile Jacking** & **Pile End** & **Pile Side** & **Pile Side** & **Percentage (\%)** \\  & **Pressure (kN)** & **Resistance (kN)** & **Resistance (kN)** & **Percentage (\%)** \\ \hline PS1 & 1.787 & 1.192 & 66.7 & 0.595 & 33.3 \\ PS2 & 2.126 & 1.411 & 66.3 & 0.715 & 33.7 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Percentage of pile end resistance and pile side resistance to pile pressure at the end of pile jacking.  
Figure 7: The relationship between pile jacking pressure, pile end resistance, and pile shaft resistance. (**a**) Test PS1. (**b**) Test PS2.  
higher end resistance and side resistance compared to PS1, with margins of 0.219 kN and 0.12 kN, respectively.  
The following is the analysis combined with the \"adhesion-plough\" theory: in the process of piling jacking, disparate durations of pile ploughing action impact varying depths of the soil, engendering differential degrees of pile-soil separation. The uppermost stratum of soil generates a thicker slurry water film, leading to a discernible attenuation in adhesion. As the soil depth increases, the ploughing action diminishes, which causes thinner slurry water film and a concurrent escalation in pile side resistance. Notably, the top 10 cm of the test soil layer comprises a gravel cushion. Consequently, the pile end resistance in both test groups increases rapidly within the first 10 cm of pile sinking depth, while the total side friction resistance remains minimal. Moreover, the piling machine in PS2 amplifies the lateral pressure of the soil around the pile during the jacking process. As a result, compared to test PS1, the slurry water film between the pile and soil at equivalent soil depths is thinner, leading to increased adhesion points and, subsequently, to higher pile end resistance and side friction resistance.  
The discrepancy between the end resistance and the total side friction resistance of the two test piles at each jacking depth is illustrated in Figure 9. Significantly, at a depth of approximately 30 cm, the difference in pile end resistance between the two groups is minimal, while the variance in total side friction resistance is the most significant. Comparatively, with reference to test PS1, the growth rate of the total side friction resistance of test PS2 between 20 and 30 cm of pile depth is accelerated. This can be attributed to the lateral deformation of the soil induced by the static press-in piling machine. However, due to the varying soil depths, the lateral extrusion deformation is not uniform. In this experiment, the influence of the piling machine results in larger lateral extrusion of the soil at 20 to 30 cm, leading to a reduced gap between the pile and the soil and to the ploughing force becoming larger. Thus, the total side friction resistance increases.  
Figure 8: Comparative analysis diagram of pile jacking resistance.  
Figure 9: Pile jacking resistance difference curve.