Performance Analysis of Pile Group Installation in Saturated Clay
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Very interesting and usefull article. I have a few questions:
1. What is the reason for assuming no permeability at the edges of the numerical model? This is a barrier to water filtration.
2. There are no units in the figure 2 and 14.
3. Figures 3 and 4 show a comparison of the calculation results with other results (theoretical and measured by other authors). Were the calculations and measurements for the same piles and the same ground conditions as for the scheme in Figure 1 and the parameters from Table 1?
4. In Figure 14a, negative values of pore water pressure were found under the piles. However, it is clearly visible that these values are above zero (positive)
5. It is not clear how the vertical bearing capacity Q(t) was determined.
Best regards
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe manuscript examines the effect of subsequent pile installation on adjacent piles in saturated clay. After validating the newly proposed simulation model by comparing centrifugal model tests and simulations on radial displacement and pore water pressure under a single pile installation, the study explores the impact of subsequent pile installation on the lateral and vertical displacement, bearing capacity of adjacent piles, and pore water pressure of surrounding soils. Additionally, a parametric study on factors such as pile center distance and L/De was conducted. While the reduction in impact with increased pile center distance is acknowledged, the detailed mechanism is not well documented. Furthermore, the numerical modeling is briefly and roughly described, making it difficult for readers to assess its reliability and accuracy. The results are also dependent on geomaterial conditions, and it remains unclear how to provide guidance for pile group engineering during the design phase and how to account for the group pile effect on horizontal and vertical bearing capacity. Therefore, it is necessary to revise the manuscript in response to the reviewers' concerns.
1) The numerical modelling on the pile installation are not well documented in this manuscript though the reference is cited. And the method how to determine prameters on soil-pile surface are not clear.
2) The reason and mechanics why the negative pore pressure in the little deep area from the pile tip is not well discussed. It is guess that the negative pore pressure may be generated by the volume increase of the soil due to the positive dilatancy, but it is not well mentioned.
3) Line 245: It is doubtful that the peak vertical displacement of the adjacent pile increase with the increase of the pile center distance, S. The reduction in impact with increased pile center distance is likey more reasonable.
4) Line 258: The following sentce is also doubtful. "As the lateral displacemnt of the adjacent pile decreases, the vertical component of the friction force on the pile increase." Pile center distance directly relates to the constraint effect of the surrounding soil.
5) Line 270: It is too briefly expressed. Please provide more the detail to avoid the misunderstanding.
6) Figure 14: Once again, why the negative pore pressure in the little deep area from the pile tip is genereted? Providing the various strain of the surrouding soil is more helpful to understand the mechanism. The unit should be shown.
7) Figures 15 and 16 etc.: In the geotechnical engineering field, the compressive pressure and the effective stress is expressed by positive.
8) Figure 16: It is not clear how to calculate the bearing capacity of the adjacent pile. The detail should be explicitly mentioned. This tendency is depending on the soil condition. It is better to mention the soil type dependency.
9) Line 344: This results also depends on the soil condition. It should be mentioned to avoid the misleading.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe rivised manuscript emphasize the precious of the manuscript following the reviewer's comments. However, it is still not clear for reviewwer why the stress reduction below the pile is generated and why the tensile expansion in the soil below. I guess it is caused by possitive dilatancy because it is using undrained analysis. It is better to mention the mechanism more clearly.
Author Response
Comments 1: The revised manuscript emphasize the precious of the manuscript following the reviewer's comments. However, it is still not clear for reviewer why the stress reduction below the pile is generated and why the tensile expansion in the soil below. I guess it is caused by positive dilatancy because it is using undrained analysis. It is better to mention the mechanism more clearly.
Response 1: Thank you for pointing this out. In the revised manuscript, a stress reduction area is observed at both the top and bottom of the pile, as illustrated in Figures 2(c) and 2(d). Yang et al. (2020) demonstrated that tensile-induced dilation of the soil leads to a reduction in volumetric stress, with tensile stress being positive in FLAC3D. Hence, it can be inferred that the occurrence of stress reduction and negative pore pressure around the pile top and bottom are caused by tensile-induced dilation of the soil under undrained conditions, with specific modifications noted in lines 155-161.
References:
Yang, Z. X., Gao, Y. Y., Jardine, R. J., Guo, W. B., & Wang, D. (2020). Large deformation finite-element simulation of displacement-pile installation experiments in sand. Journal of Geotechnical and Geoenvironmental Engineering, 146(6), 04020044.
