Mechanical Behavior Analysis of Excavation and Retaining Piles in Gravel Formation along Adjacent Railways: A Comparative 3D FEM Study with Monitoring Data

Round 1

Reviewer 1 Report (New Reviewer)

Mechanical Behavior Analysis of Excavation and Retaining Piles in Gravel Formation along Adjacent Railways: A Comparative 3D FEM study with monitoring Data

This paper highlights a vital FEM study for analyzing the mechanical behavior of the gravel layer in response to the excavation. English is well written. The authors may want to consider the following comments:

Line 79: "quarry design" or "quality design"? Please check it.

Line 219: How did the authors get the values of cohesion and friction angle? Have the authors employed some empirical equations to derive them directly from SPT outcomes? If that's the case, please refine it.

Line 271: The Reviewer thinks the mechanical properties pertaining to the counterpart materials are isotropic. However, the initial stress field is not isotropic. The vertical stress is, in general, different from that in the horizontal direction.

Line 273: The authors state that the pore water pressure is not considered. Whether the reason to consider such a drained condition is the fact that water was previously pumped out? The authors should explicitly explain it.

Line 329: It should be "kPa" instead of "KPa". Please correct it.

Author Response

Dear reviewer,

Thank you for taking the valuable time to review our manuscript. Your comprehensive and insightful comments and suggestions for our submission are sincerely appreciated, which significantly enhance the presentation of this manuscript. The manuscript has been revised according to your comments and suggestions from you.

Ask to revise some parts of the manuscript, which have been revised as followings:

(1) Line 79: "quarry design" or "quality design"? Please check it.

It should be "quality design", it has been corrected in line 79 of the manuscript.

(2) Line 219: How did the authors get the values of cohesion and friction angle? Have the authors employed some empirical equations to derive them directly from SPT outcomes? If that's the case, please refine it.

Regarding the values of parameters such as cohesion and friction angle, the parameters of the backfill layer and the yellow sandy silt were obtained through standard penetration test (SPT) and thin-wall tube samplers, and were taken to the laboratory for uniaxial compression tests and direct shear tests. However, the parameters of the gravel layer are estimated using empirical formulas.

It has been added and modified lines 206~210 in the manuscript

(3) Line 271: The Reviewer thinks the mechanical properties pertaining to the counterpart materials are isotropic. However, the initial stress field is not isotropic. The vertical stress is, in general, different from that in the horizontal direction.

Totally agree with you. The physical properties and mechanical behavior of the material are isotropic, but this study adopts the assumption that the initial stress is isotropic for the convenience of calculation.

(4) Line 273: The authors state that the pore water pressure is not considered. Whether the reason to consider such a drained condition is the fact that water was previously pumped out? The authors should explicitly explain it.

Since deep well pumping is implemented in the work area and the pre-precipitation water level is lower than the excavation surface, the pore water pressure is not considered in this study.

It has been added and modified lines 276~278 in the manuscript

(5) Line 329: It should be "kPa" instead of "KPa". Please correct it.

It should be " kPa ", it has been corrected in line 335 of the manuscript.

Thank you very much for your comments and suggestions.

Sincerely,

Yu-Lin Lee

December 25, 2022

Professor

Department of Civil Engineering, Chung-Hua University

707, Sec.2, Wufu Rd., Hsinchu, Taiwan 30012, R.O.C.;

+886-35186701; [email protected]

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

1. There is repetition in the text. Lines 73-76 repeat lines 33-36

2. There are some tautologies in the text, that is desirable to avoid.

3. I think, that the weight units are confused: concrete  unit weight is not 24.53MPa/m, it is rather

24.53 kPa/m. 

That is why iso-value of initial vertical stress in Figure 7 (d) looks unreal. I think units are confused as well and stresses are measured in kPa , not in MPa in this case. 

4.   It is not clear what the line is in Fig.8. a), b).  If this is a support wall, why we do not see it in 3D scheme?

 

5. There is no full design scheme that includes boundary conditions and loading conditions for either 2D or 3D simulation. This makes it difficult to assess the reliability of calculations

Comments for author File: Comments.pdf

Author Response

Dear reviewer,

Thank you for taking the valuable time to review our manuscript. Your comprehensive and insightful comments and suggestions for our submission are sincerely appreciated, which significantly enhance the presentation of this manuscript. The manuscript has been revised according to your comments and suggestions from you.

Ask to revise some parts of the manuscript, which have been revised as followings:

(1) There is repetition in the text. Lines 73-76 repeat lines 33-36

The duplicated text has been removed in lines 73-76 and revised in the manuscript.

(2) There are some tautologies in the text, that is desirable to avoid.

Thank you for your reminder, I have re-examined and avoided this phenomenon in the text.

(3) I think, that the weight units are confused: concrete unit weight is not 24.53MPa/m, it is rather 24.53 kPa/m. That is why iso-value of initial vertical stress in Figure 7 (d) looks unreal. I think units are confused as well and stresses are measured in kPa, not in MPa in this case.

The unit of concrete unit weight is 24.53 kPa/m, and line 215 has been revised in the manuscript. In addition, the stress unit in Fig. 7(d) is MPa, which is correct.

(4) It is not clear what the line is in Fig.8. a), b).  If this is a support wall, why we do not see it in 3D scheme?

In the two-dimensional numerical analysis, two retaining structures, the vertical wall, and the retaining pile are considered, but in the three-dimensional numerical analysis, only the effect of the retaining pile group is considered.

(5) There is no full design scheme that includes boundary conditions and loading conditions for either 2D or 3D simulation. This makes it difficult to assess the reliability of calculations

Regarding the assumption of boundary conditions, in the two-dimensional numerical analysis, the left and right sides and the bottom are fixed by roller, while the upper side is the free side. In addition, in the three-dimensional numerical analysis, the front and rear sides, left and right sides and bottom are also fixed by roller, and the upper side is also free.

Thank you very much for your comments and suggestions.

Sincerely,

Yu-Lin Lee

December 25, 2022

Professor

Department of Civil Engineering, Chung-Hua University

707, Sec.2, Wufu Rd., Hsinchu, Taiwan 30012, R.O.C.;

+886-35186701; [email protected]

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

It is a very interesting technical study. However, it is not a research study at all and I must recommend its rejection according to the type of journal. I would recommend to try to publish it in a journal focused on dissemination.

Some specific comments:

• Line 17: developed three-dimensional finite element program? I understand that the authors are only users of the software.
• Which software and versions were used?
• The introduction is too short regarding the main advancement done so far and the lack of knowledge that require research. Besides, the introduction is mainly focused on the case study characteristics.
• The goal defined is not for a research study
• The references are two short. I recommend that the authors make an intense improvement of the fundamental publications related to the topic

Author Response

Thank lots the referee for taking the time to review the manuscript. Your comments and suggestions have been corrected in the manuscript, and the responses are as follows:

(1) Line 17 talks about the three-dimensional finite element program developed by the research center, whose program name is CHUGEO5, a finite element software developed from 1994 to the present. If reviewers are willing to learn more, we are willing to provide descriptions of relevant finite element program modules and program execution steps and processes.

(2) For the problem that the introduction and references are too short, the description and the number of references have been increased according to the comments. (Modifications are shown in the Introduction and References sections)

Corrections and clarifications above, thank you very much!

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Very little attention has been given in this area. This could be a reason for the novelty of proposed method in this paper. The manuscript has been well written. The research plan was properly implemented and the results were clearly presented. The paper contains useful material and valid results. After reviewing the paper, I would like to say that the paper contains useful material and valid results, and there is, therefore, a recommendation to publish it in your Journal. The followings are a few suggestions to improve the overall quality of the paper.

Author Response

Thank lots the referee for taking the time to review the manuscript, and thank you for acknowledging the results of this research!

Author Response File: Author Response.pdf

Reviewer 3 Report

1.             1-  The introduction needs to be rewritten as it starts directly into the project without explaining the bases of the problem.

2.           2-    The literature needs to be more comprehensive and present some of the findings from previous work.

3.               3- The authors need to identify the benefit of the study and how it can be used in practice.

4.               4- The paper needs to be reviewed by a native speaker of the English language.

5.               5- The authors from the beginning of the paper talking about the gravel layer, it is important to descript eths layer in detail and not assume the reader is aware of the geology of the area under consideration.

6.               6 - L100, more details about the pumping rate are required and what is the groundwater level after the dewatering.

7.               7- It is required to provide a borehole log for the site under consideration.

8.               8- Which software was used for the 2D and 3D FEA?

9.               9- In L150 the authors used the MC model and there are some limitations regarding the loading and unloading stages which may affect the results. It is required to clarify these limitations and how it was eliminated during the study?

Author Response

Thank lots the referee for taking the time to review the manuscript. Your comments and suggestions have been corrected in the manuscript, and the responses are as follows:

(1) The introduction has been supplemented as shown in the introduction section.

(2) A bibliography description has been added to introduce some findings from previous work as indicated in the bibliography section.

(3) In the conclusion section, supplementary description of the advantages of this study and the use of the results obtained so far in future practice. “The key to the success of this project lies in the use of mechanical excavation and the use of vertical walls, retaining piles, and tie beams as the main supporting members when excavating the gravel layer adjacent to the railway track. The results of the study will be provided for future reference to related projects.” (as shown in the conclusion section).

(4) This paper has been reviewed by native English speakers.

(5) Please refer to the revised introduction section.

(6) Additional notes on pumping rates and groundwater levels after draining, “during the construction of retaining piles in this project, the gravel water level needs to be lowered to 10.25m below the surface. When the initially designed groundwater is 3.0m below the surface, the estimated discharge drop demand is 7.25m to prevent the gravel from collapsing due to seepage, thus creating a danger to adjacent railway tracks.” (Supplementary instructions such as L111~L115).

(7) Regarding the provision of the site borehole log, as shown in the picture in the attached file, due to the poor resolution of the picture, it cannot be included in the manuscript.

(8) Line 17 talks about the three-dimensional finite element program developed by the research center, whose program name is CHUGEO5, a finite element software developed from 1994 to the present. If reviewers are willing to learn more, we are willing to provide descriptions of relevant finite element program modules and program execution steps and processes.

(9) According to the use of the MC model and there are some limitations regarding the loading and unloading stages which may affect the results. Mohr-Coulomb theory is a mathematical model (yield surface) describing the response of brittle materials such as concrete, or rubble piles, to shear stress as well as normal stress. Most classical engineering materials somehow follow this rule in at least a portion of their shear failure envelope. Generally, the theory applies to materials for which the compressive strength far exceeds the tensile strength. In geotechnical engineering, it is used to define the shear strength of soils and rocks at different effective stresses.

Corrections and clarifications above, thank you very much!

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Based on the comments made at the initial revision:

- The introduction has been barely improved. It is not necessary to include more references in bulk, but to enrich the proposal, for instance the added lines (33 to 37) make some statements without any reference to back them

- It is important to include the type of software and version in the text.

- The goal has not been addressed based on the comment from the first revision.

- I recommend the authors include a more detailed answer of the comments from the reviewers, gathering question and answer.

Overall, the manuscript has been barely improved and all the issues found in the initial version remain the same. I regret to tell the authors I think it is not suitable to be published as a research paper.

Author Response

Response to referee #1

Thank lots the referee for taking the time to review the manuscript. Your comments and suggestions have been corrected in the manuscript, and the responses are as follows:

(1) A field drill record was added, as shown in Figure 6, and modified in the manuscript. (Lines 180~181)

(2) The details about the FE program are modified and added to the manuscript. (Lines155~156).

Corrections and clarifications above, thank you very much!

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors' response needs to be implemented in the paper not just the response to the reviewer. for example, the details about the soil and bore log and the details about the FE program.

Author Response

Response to referee #3

Thank lots the referee for taking the time to review the manuscript. Your comments and suggestions have been corrected in the manuscript, and the responses are as follows:

(1) Regarding the provision of the site borehole log, as shown in Figure 6 and modified in the manuscript. (Lines180~181)

(2) The details about the FE program are modified and added to the manuscript. (Lines155~156).

Corrections and clarifications above, thank you very much!

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

I regret to tell the authors that they have just made some small cosmetic changes, avoiding the fundamental comments about the manuscript.

In my opinion the manuscript should be rejected

Author Response

Thank lots the referee for taking the time to review the manuscript. Your comments and suggestions have been corrected in the manuscript, and the responses are as follows:

• Line 17 talks about the three-dimensional finite element program developed by the research center, whose program name is ChuGeo5 (version 5.0), a finite element software developed from 1994 to the present. In addition, the description of the finite element program is added to the manuscript. (Lines155~156).
• For problems with too short introductions and references, the number of descriptions and references has been increased according to the comments. (Modifications are indicated in blue in the Introduction and References section)
• The authors have done their best to make revisions to the manuscript that hopefully will meet the goals you have requested of the reviewers.

Thank you very much and wish you peace and joy!

Author Response File: Author Response.docx