Experimental Study on the Difference Mechanism of Shaft Resistance between Uplift Piles and Compressive Piles
Round 1
Reviewer 1 Report
General Comment:
I am pleased to read the draft titled “Experimental Study on the Difference Mechanism of Shaft Resistance Between Uplift Piles and Compressive Piles” and share my opinions. In this paper, the authors attempt to investigate the formation mechanism of the lower shaft resistance of uplift piles compared to compression piles by a set of model tests, which would be interesting to see. The findings show that the distribution range of additional stress caused by a single pile is within 6d from the axis of the pile.
Authors are suggested to validate the model with one of the numerical software and include the same in the article. Finally, the authors should have checked the draft text carefully or proofread it again to correct most of the typographical errors.
Detailed comments:
1. Authors are suggested to highlight the novelty and importance of this research in the article.
2. Line No. 18-19: The part of the sentence included in the abstract doesn’t give the intended meaning.
3. Line no. 92 and 98: authors are suggested not to use words like we, us, rather better if written in third person perception. Also, suggested to write manuscript in same either past or present.
4. Line no. 114: Authors mentioned “The soil is made of silt”, Does it mean, the soil is classified as "Silty Soil".
Why the Particle size distribution curve for the soil is not included in the article, suggested to include the same?
5. Line no 118: “soil is made by layered filling”, As, soil cannot be made in lab. Does it mean "soil is filled in the model box in layers of 200mm"? Need to correct the sentence.
6. Line no 121: How did authors confirmed the soil density of 1.61 g/cc, was it measured at different locations of the model box before the start of the model test?
7. Line no. 122-123: “The compressive pile is soil-free at the bottom of the pile. Under the pile bottom is a hollow bamboo cage”, seems like, this is not giving the intended meaning, Authors are suggested to include the schematic diagram of the same to assist the reader.
8. From Table 1: it is observed that ds<75micron is about 76.3%. Since % passing 75micron sieve is more than 50%, whether authors performed wet-sieving analyses followed by hydrometer or pipette analysis, in order to decide the soil classification. Since 75micron passing can contain both clayey (ds<2micron) and silty (2micron<ds<75micron) sized particles. Need to be checked properly. what are the Atterberg's limits of the soil used in the study.
How the soil is classified as silty soil? Why % of clay sized particles are not mentioned in the table.
9. Figure 3: Pile used is not visible in the figure.
10. Line no 141: “After the completion of all production”, Does it mean, "after completion of the soil filling in model box"? need to correct the sentence.
11. Line no 142: “resting”, Did the authors left the soil ideal for 20days after filling the soil in the model box? If yes, did the soil was open to air or any special care was taken to reduce the sudden drying of the soil, as it may form shrinkage cracks in fine grained soils?
12. Line no 142-144: What are Ring Knives? why did authors collected the soil after the test, did they perform any other soil tests after the end of model tests?
13. Table 2: Even after the table caption has the word "indices" because, no indices are included in the table. Authors are suggested to include the liquid limit, plasticity index in this table, as it will also assist one in deciding the soil classification.
Why, slash (/) is used after every symbol? Instead, authors are suggested to include the units within brackets, after the symbol.
What tests were performed in estimating the shear-strength parameters (c and phi) of the soil in the study? Are these, the effective stress parameters or total stress parameters?
14. Line 150 and figure 4: “chart”, Does it mean the compressive pile test setup?
15. Line no 154-160: “Q-s curve and s-lgt curve”, What are Q-s, s-lgt curves? Authors are suggested to clearly mention expanded form of the same once before using the short forms in the article.
16. For all plots: For all the graphs or plots, Authors are suggested to include the units of the axis titles within the brackets or parentheses. Also, symbols used in the plots are not clearly visible, authors are suggested to use higher sized symbols and the figures with higher resolution.
17. Line 179-180: “in Figure 7 when the measured ultimate load is 1700 N”, Need to correct the sentence.
18. Table 3, row-2: As per authors explanation in text, earth pressure sensors are located at 50mm away from the pile side, i.e., 75mm away from the pile axis.
Hence, for x=0.075m, SigmaZ is found to be 1.4867kPa,
Whereas, sigmaZ given is 1.2425kPa, how does author defend this?
What should be the units of x, for calculating the sigma Z (line no 206, 233)?
19. Line no 245: authors have used the word “preferably”, Authors are suggested not to use such unconditional words in the article.
20. Line no 251-252: what is (tou)s1d
Authors are suggested to define this as a term and use the same for explanation.
21. Table 8: Did authors used the same pile dimensions for calculating the ultimate bearing capacity of the uplift pile? Authors are suggested to include the equations suggested by Meyerhof (1973) and Deshmukh (2010) and the present methos in the form of table.
22. Line 300-301: authors used the word “analysis”, Did authors perform any kind of analyses (numerical or analytical)? if not, that word must be replaced by "a series of model tests".
23. Line 304-310: Authors are suggested not to make general conclusions, it must be supplemented by the result obtained from the study.
24. Authors are also suggested to cite some of the recently published literature in the article and list the same in the bibliography.
Comments for author File: 
Comments.pdf
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Dear Authors,
This manuscript presents an interesting study on the formation mechanism of Shaft Resistance between Uplift and Compressive Piles. The unloading effect of the uplift pile and the loading effect of the compressive pile on the difference in additional stress are quantitatively studied in this paper through micro-earth pressure cells buried in the soil.
It is a good reference to researchers, equipment users, and specification developers in geotechnical engineering fields. Overall, it is a well-written manuscript. I suggest that this manuscript can be considered for publication after revision. All the comments and notes are added in a PDF file.
Sincerely
Sohrab
Comments for author File: Comments.pdf
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The authors aim to examine the hypothesis that the capacity of piles under axial and tensile loading may differ, through laboratory-scale experiments. However, there are a few concerns that need to be addressed as follows:
- The choice of silt as the testing material for soil needs to be justified. Silt is a fine-grained soil that is known to exhibit undrained behavior and a low response to changes in the stress surrounding the pile shaft. In my opinion, it might be challenging to use silt as the soil in physical model tests to study the effects of changing confining stress.
2. The method for control of the uniform moisture content through out soil in testing chamber need to be explained in detail. Is there any test to ensure the uniformity of preparing silt for depth of 1.7 m. The method to spray water needs to be explained in detail to ensure the similar between two physical testing chamber for axial and tensile loading pile.
3. The authors stated that, the testing chamber needs to wait for 20 days before testing. The reason support needs to be stated. Is there any test to measure its index and 3engineering properties of silt before conduction pile loading test.
4. The details of the testing procedures should be specified based on Table 2. The testing method and details should be thoroughly described in the paper, particularly for the friction angle and cohesion of the soil. These parameters are crucial in calculating the pile friction angle and verifying the authors' hypothesis.
5. The authors should provide a detailed explanation of how the s-lgt curve in Figure 6 was obtained.
6. 6.The authors should explains how to get the pile capacity from a load deformation curve of pile. It seem to be using the last point of testing or end of test. It is not a real failure state of pile. The other suitable method needs to be use to obtain the pile capacity.
7. In the section "Calculation and analysis of the shaft resistance of the pile", the method for calculating the shear stress in the pile should be thoroughly explained as follows:
1. The authors should specify whether the stress for calculation is obtained from the miniature pressure transducer, and indicate the direction of measurement of the stress.
2. The friction angle used for calculation should be clearly stated. In my opinion, the friction angle for silt material may be quite high. The authors should compare their results with previous research findings."
8. In the section "Calculated and measured values of uplift bearing capacity", the methods used to calculate the pile capacity should be thoroughly explained, including the assumptions and parameters used in the analysis."
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
General Comment:
This Manuscript can be accepted for publication if the authors respond to the following comments and include the same in the manuscript.
Detailed comments:
1. From Table 1: It is observed that ds<75micron is about 76.3%. As per, section 3.3.4 and 3.3.5 of GB: 50021 – 2001, If % passing 75micron sieve is more than 50%, then the classification Silty soil, Silty-clay and Clay is truly dependent on Plastic Index (Ip),
i.e., if 10%<Ip<17% then, soil can be classified as “silty clay”, and
if Ip>17% then soil can be classified as “Clay”.
Since, authors mentioned that they have not performed Atterbergs’ limits, but we suggest authors to reconsider and include the Atterbergs’ limits so that the clear explanation for soil classification is brought in the manuscript.
2. Line no 142: “resting”, Did the authors left the soil ideal for 20days after filling the soil in the model box? If yes, did the soil was open to air or any special care was taken to reduce the sudden drying of the soil, as it may form shrinkage cracks in fine grained soils? (Authors did not answer this comment to the point)
3. Line no 142-144: What are Ring Knives? why did authors collected the soil after the test, did they perform any other soil tests after the end of model tests?
Authors responded “after model test, they have conducted physical and mechanical parameters test of soil”
But the results of the same are advised to include in the manuscript.
4. For all plots: For all the graphs or plots, symbols used in the plots are not clearly visible, authors are suggested to use higher sized symbols and the figures with higher resolution. (No changes were found in figures from the previously submitted manuscript, so authors are suggested to reconsider this comment)
Also cite papers on finned piles like Soil Structure Interaction of High-Rise Building on Finned Pile Mat, if relevant as fins were found to increase the pile resistance.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
Thank you for your response to my comment on your paper. I appreciate your insightful explanation of the main argument and the evidence you provided. I learned a lot from reading your paper and I look forward to reading more of your work in the future.
Author Response
Thank you very much for your recognition of this paper. Thank you again for your valuable feedback on our article, which we use to improve the quality of the paper.
