## 3 Test Results
### Excess Pore Water Pressure
At a radial distance of 2.1 m from the pile axis, the excess pore pressure generated during PGP pile construction is smaller than driven piles, and the pore pressure gradient is much smaller than driven piles. After a construction pause of one day, the pore pressure at a depth of 12 m has dissipated almost completely because the shallow pore pressure is more easily discharged from the upper surface. The pore pressure at a depth of 22 m dissipates more slowly because the water pressure in the middle of the pile cannot be quickly drained from the top and bottom ends, and the drainage conditions are worse than in the upper and lower parts. Table 4 shows that the gradient of pore pressure changes at the same depth decreases with increasing radial distance. Generally, the greater the depth, the larger the gradient of pore pressure increases. Figure 7: _Cont._  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & & \multicolumn{2}{c}{**Drilling Stage**} & \multicolumn{2}{c}{**Planting Stage**} & \multicolumn{2}{c}{**Resting 1 Day**} \\ \cline{3-7} \begin{tabular}{c} **\(u_{\text{max}}\) (kPa)** \\ **(kPa/min)** \\ \end{tabular}   
Furthermore, the soil layer is muddy silt clay with high porosity and low permeability. In contrast, pore pressure dissipates faster in clayey silt. At the same depth, the dissipation rate of excess pore water pressure decreases with increasing radial distance from the pile axis after a one-day pause. The maximum excess pore water pressure \(u_{\max}\) measured by each pore pressure gauge around the pile during the PGP pile construction is divided by the effective stress \(\sigma_{v}(h)\) of the overlying soil at that point, and the distance of the pile axis \(r\) is divided by the diameter of the borehole \(d\) for normalization. As shown in Figure 8, when \(r<3.5\)\(d\), the pore pressure decays a little more rapidly than when \(r>3.5\)\(d\). The excess pore pressure has an almost linear relationship with the distance along the pile circumference compared to the average value, which can be expressed by the following equation. \[\frac{u_{\max}}{\sigma_{v}(h)}=-0.06\frac{r}{d}+0.45 \tag{1}\]  
In the equation, \(u_{\max}\) and \(\sigma_{v}(h)\), respectively, represent the maximum measured excess pore water pressure at the point and the effective stress of the overlying soil. \(r\) is the distance between the measurement point and the pile axis, and \(d\) is the diameter of the pre-bored grouted planted pile. It can be clearly seen from the figure that the excess pore pressure ratio at \(r=3.5\)\(d\) for the driven pile is significantly greater than that of the PGP pile. If the line is extended and intersects the horizontal axis at a certain location, the construction-caused excess pore pressure range can be determined. However, considering that, the change in excess pore pressure near the pile axis is gradually steep. In contrast, the change in excess pore pressure far from the pile axis is gradually gentle; it is inferred that the influence of excess pore pressure beyond the 7.5 \(d\) range is relatively small. Therefore, it can be concluded that the range of excess pore pressure influence implanted by the pile is much smaller than the 15 \(d\) range of excess pore pressure influence caused by the driven piles measured by [PERSON] [9].