## 4 Conclusions  
This study examines soil disturbance and environmental impact caused by PGP piles and driven piles. The main findings are as follows:  
1. At a certain distance below, the soil is affected more by pile shaft friction than bottom squeezing. Shallow soil has a lower pressure increment and quicker recovery than deep soil. Planting drill generates substantial soil squeezing towards the pile body. Once the drill is below a layer, pressure stops increasing. More than 1/3 of pile body is not squeezed in the planting process;
2. Driven piles displace soil away, compacting it due to pile impact. For PGP piles, the soil moves towards the pile during drilling, and it moves away during planting. Compaction and displacement are less distinct, with soil recovery. The lateral soil displacements by PGP piles are obviously less than by driven piles;
3. Excess pore pressure by PGP pile construction reduces with the increase of radial distance. It mainly happens during drilling and planting, with minimal change in shallow soil during planting. The pore water pressure gradient at a depth decreases as radial distance increases. Deeper depths result in steeper pore pressure gradients. At r = 3.5 \(d\), excess pore water pressure and its gradient are smaller than by driven piles. After a one-day break, the dissipation rate slows down. The maximum excess pore pressure value varies linearly with increasing radial distance, and the influence distance is no more than 7.5 \(d\);
4. Horizontal vibration exceeds vertical near the pile machine, and it decreases with radial distance. Vibrations from PGP piles are consistently smaller than by driven piles. The max vertical vibration is about 0.5 times that of driven piles, and the max horizontal vibration is about 0.58 times that of driven piles. The vibration by driven piles leads to discomfort, but this does not happen during PGP pile construction;
5. The noise generated by PGP pile construction is lower than by driven piles, with a maximum value of 8 to 15% lower than by driven piles at the same distance. The noise generated during PGP pile construction decreases significantly with the distance increase, while driven piles still produce more than 100 dB of noise at 20 m away. The noise limit can be met 17 m away from the PGP pile;
6. This study provides a reference for the selection of two pile types. In the future, more detailed tests can be carried out and compared with numerical simulations.  
Conceptualization, F.S. and Y.D.; methodology, Y.D.; software, F.S.; validation, Y.D., R.Z. ([PERSON]) and R.Z. ([PERSON]); formal analysis, R.Z. ([PERSON]); investigation, S.C.; resources, R.Z. ([PERSON]); data curation, F.S.; writing--original draft preparation, F.S.; writing--review and editing, Y.D.; visualization, F.S.; supervision, R.Z. ([PERSON]); project administration, R.Z. ([PERSON]); funding acquisition, Y.D. and R.Z. ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
This research was funded by Key Project of Ningbo Natural Science Foundation (grant number 2023J004) and the Science and Technology Innovation 2025 Major Project of Ningbo, grant number 2022Z030).  
Not applicable.  
Data Availability Statement: The data used to support the findings of this study are currently under embargo while the research findings are commercialized. Requests for data, 12 months after publication of this article, will be considered by the corresponding author.  
We acknowledge the funding support from Key Project of Ningbo Natural Science Foundation (grant number 2023J004) and the Science and Technology Innovation 2025 Major Project of Ningbo, grant number 2022Z030). The authors want to express gratitude to [PERSON] and [PERSON] for their valuable advice on this study; this paper could not have been completed well without them.  
The authors declare no conflict of interest.