Field Test Study on the Bearing Capacity of Extra-Long PHC Pipe Piles under Dynamic and Static Loads
Round 1
Reviewer 1 Report
Good and valuable research has been done.
This atudy is about Field Test Study on the Bearing Capacity of Extra-long PHC 2
Pipe Piles under Dynamic and Static Loads
In this study,
PHC pipe piles are widely used in various engineering foundations, which have the advantages of high single pile bearing capacity, strong adaptability to geological conditions and highdegree of construction mechanization. In order to study the vertical compressive bearing performance and settlement characteristics of ultra-long PHC pipe piles, high-strain dynamic detections
and static load tests were carried out on four PHC piles with a diameter of 0.9 m on site. It can be seen from the field test that the time-dependent of the bearing capacity of prefabricated pipe piles was obvious. By the end of the dynamic test, the bearing capacity of each test pile increased by 27% to 66%. The static load test also verified the rationality of the value of the restitution coefficient. Therefore, the final bearing capacity of the pile foundation can be predicted by using the high-strain initial driving results and the restitution coefficient, which can reduce the repeated driving process, effectively save the cost, and improve the engineering efficiency. Under 2.1 times the design load, the change range of the pile concrete modulus is from 37.5 GPa to 52 GPa, the change range of the pile side friction resistance is from 0 kPa to 97 kPa, and the change range of the pile end to pile bottom load ratio is from 0% to 7.54%. During the test, the shaft friction and end bearing of the lower part of the piles were not fully mobilized. The shaft friction resistance, the end resistance and the movement behavior of the pile top and the end of the piles can provide parameter references for the subsequent design and construction of the piles.
In the opinion of the reviewer, this manuscript note could be accepted after the major revisions and re-evaluation.
1- Authors are recommended to emphasis the novelty and significance of the study in more detail.
2- Authors are recommended to discuss the obtained results with literature in more detail.
3- Please use the appropriate font size in Figure 1.
4- It is recommended to prepare a table in the introduction section and list the works done in order of year.
5- Authors are recommended to provide a more complete explanation about PDA tests and test analysis.
6- Some of the references provided are old. It is suggested that a number of recent papers that are new and have been published in the last five years be used in the introduction and references list and about fractures.
7- It is recommended to remove the gridlines for a better display of the figures.
8- In Figures 7, 8, 9, 10, 11, the captions c and d have been moved from their position below the figure. be in the correct position.
9- The conclusions section are proposed to be rewritten and using bullets instead of numbers in this section.
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The article deals with methods and results of PHC pile testing. The presentation of the testing is extensive and well organized. The article could be interesting for the readers of the Journal and is recommended for publication. However, there are few points I would like to mention.
1) The Title of the article and Abstract states that the bearing capacity of the PHC (prestressed high-strength concrete) pipe piles were investigated; but in section 2 (line 85) and in Conclusions (lines 456 and 457) the term “steel pipe pile” is used. For example “In this paper, dynamic and static load field tests of prefabricated steel pipe piles are carried out.” – text in lines 456, 457. Then, it is not clear, how the steel pipe pile is related to PHC pipe pile and which type of piles was investigated?
2) The article presents only experimental data; there are no numerical or analytical estimations or simulations done that would increase the significance and attractiveness of the article.
3) Abbreviation PHC was defined two times in the article (in line 27 and line 38), but abbreviation EXT that was used in lines 41 and 42 is not defined at all.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
1. In the abstract the acronym PHC was introduced for the first time; it should be defined (Pretensioned prestressed high strength concrete pipe).
2. The literature is not comprehensive and needs to present some of the findings from previous work.
3.3. More details about the soil properties are required.
4. 4. More details about the pile load testing procedure are required.
5. 5. What is the effect of the pile driving to the dense layer and how it can be evaluated?
6. 6. Fig. 5b is very hard to follow due to a large number of curves, I suggest splitting it into 2 figures. Or it could be presented in a bar chart to show the final settlement at different depths.
7. The authors need to explain the befit of the research to the industry practice and how the finding from this test can be utilized.
8.8. More points from the finding should be added to the conclusions.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The desired corrections have been made. In my opinion, the article can be accepted.
Reviewer 3 Report
No Further comments
