Study on the Influence of Foundation Pit Excavation on the Deformation of Adjacent Subway Tunnel in the Affected Area of Fault Zones

Round 1

Reviewer 1 Report

The manuscript investigates the deformation response of an adjacent subway tunnel caused by excavation in a fault zone influence area. The paper employs theoretical analysis, numerical simulation, and on-site measurement to study the deformation problems and proposes various methods to address them. While the overall content is clear, there are some areas that can be improved for clarity and precision.

Consider the following items for improvement of the manuscript:

1. Specify the purpose and significance of the research earlier in the text: Start by clearly stating the objective of the research and its importance. For example, mention that the study aims to understand and mitigate the deformation issues in adjacent subway tunnels caused by foundation pit excavation in fault zone influence areas, ultimately ensuring the safety of the subway system and supporting sustainable urban development.

2. Provide more context about the methodology: Instead of simply stating that theoretical analysis, numerical simulation, and on-site measurement were used, briefly explain how each method was employed. This will give readers a clearer understanding of the research approach. For instance, mention the specific numerical simulation techniques used and describe the types of on-site measurements conducted.

3. Use subheadings or paragraphs to improve organization: Divide the text into sections or paragraphs with informative subheadings to enhance readability and facilitate comprehension. This will allow readers to easily follow the flow of ideas and findings.

4. Clarify the findings and their implications: Provide more specific details about the results obtained from each research method and their significance. For example, mention the specific values or trends observed in the sensitivity analysis of tunnel deformation to different geological parameters, and explain how these findings can inform engineering practices and design considerations.

5. Elaborate on the practical implications and applications: Discuss in more detail how the research outcomes can be practically applied. For instance, highlight how the established deformation calculation formula and prediction model can assist engineers and planners in assessing the impact of foundation pit excavation on nearby subway tunnels and inform decision-making processes for future projects.

6. Consider using more concise and straightforward language: While technical terminology is expected in a research paper, try to simplify the language where possible to improve clarity. Use shorter sentences and break down complex ideas into smaller, digestible parts.

7. Proofread for grammar and punctuation: Double-check the text for any grammatical errors or inconsistencies in punctuation.

8. Review more relevant papers and add to the references

9.  Write the conclusions more concisely

10. Formatting of the paper should be as per journal guidelines

Author Response

Dear Dr,

Thank you very much for taking the time to review our manuscript entitled "Study on the Influence of Foundation Pit Excavation on the Deformation of Adjacent Subway Tunnel in the Affected Area of Fault Zones". We appreciate your valuable comments and suggestions, which have helped us to improve the quality of our work.

We have carefully considered all of your comments and suggestions, and have made the following revisions to the manuscript:

1. Already modified.
2. The last paragraph of the introduction provides supplementary explanations regarding the theoretical, numerical, and experimental aspects.
3. Already modified.
4. Yes, the corresponding sections of the paper have been supplemented and modified.
5. Yes, additional explanations have been provided in the conclusion section.
6. Yes, some adjustments have been made.
7. Already modified.
8. Already supplemented.
9. Already modified.
10. Already modified.

We hope that these revisions address your concerns and have strengthened the manuscript. We have also attached a marked-up version of the revised manuscript to this email to show you exactly what changes have been made.

Once again, we appreciate your insightful feedback and the time you have dedicated to reviewing our work. Please let us know if you have any further questions or concerns.

Sincerely,

Yungang Niu

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript deals with understanding the influence of foundation pit excavation on the deformation response of an adjacent subway region. This is a practical work and will appeal to the readership of Sustainability journal. However, the authors are expected to address the following technical comments while revising the manuscript.

·       How can the current study contribute to sustainability index as claimed by authors in the manuscript? Kindly elaborate on this and justify by providing valid critique.

·       What is the rationale behind choosing Mindlin solution when there are other pragmatic solutions available? Authors must justify this claim. Why Reissner theory was not considered? What are the major setbacks and important favourable points which allowed the authors to go for Mindlin solution?

·       What is the importance of “Stress Release Effect” during pit excavation on the surrounding area and how does it induce anisotropy effect on the targeted studied properties? The authors can refer to the suggested article while revising the manuscript and bring out some inferences. (https://doi.org/10.21660/2016.26.89469). Bring this inference in the introduction section.

·       Lines 40-62 – This literature review section lacks the summary. In the present form, they look as if it is a compiled study and there is no effort put into drawing the major inferences in the study. What are the gaps identified in these studied works and how does they bring in the need to carry out the present study? It may be elaborated.

·       What are the boundary conditions adopted for centrifuge modelling as the inferences drawn are closely matching with theoretical as well as field measurements? This aspect must be duly addressed while revising the manuscript.

·       Provide valid ASTM codes for the test methods adopted to calculate the parameters provided in Table 1 while revising the manuscript.

·       How does the stress release effect is accounted for in the mesh generated in Fig 7? What are the pertinent boundary conditions adopted?

·       The reviewer is extremely impressed with the quality of figures and analysis drawn for horizontal and vertical displacement along with cohesion angle variations provided in the manuscript. It is a commendable achievement.

 

·       The practical importance of the study can be highlighted in the form of a paragraph after the conclusions section. Consider including it while revising the manuscript.

Author Response

Dear Dr,

Thank you very much for taking the time to review our manuscript entitled "Study on the Influence of Foundation Pit Excavation on the Deformation of Adjacent Subway Tunnel in the Affected Area of Fault Zones". We appreciate your valuable comments and suggestions, which have helped us to improve the quality of our work.

We have carefully considered all of your comments and suggestions, and have made the following revisions to the manuscript:

1. Yes, detailed supplements have been provided in the paper.

The aim of this study is to understand and mitigate the deformation issues caused by excavation in the influence zone of the fault zone, ensuring the safety of the subway system and supporting the sustainable development of the city.

2. The reasons for choosing the Mindlin solution are its practicality and applicability in handling specific problems. The Mindlin solution is particularly suitable for addressing problems with specific geometric shapes or constraints. It offers advantages in terms of numerical computation efficiency, especially when dealing with large-scale problems.

The decision not to consider the Reissner theory may be due to several factors. The Reissner theory may not be applicable in handling specific problems, such as those with special boundary conditions or geometric constraints. Additionally, the Reissner theory may involve more complex computational procedures or numerical methods, resulting in increased computational complexity.

The main setback in choosing the Mindlin solution lies in its limitations. The Mindlin solution may have constraints regarding certain specific boundary conditions or geometric shapes, making it unsuitable for all types of problems. However, its important advantages include:

Simplified computation: The Mindlin solution offers a relatively simpler computational process, reducing the complexity and workload of computations.

Faster computation speed: Compared to more complex solutions, the Mindlin solution may provide faster computation speeds, enabling more efficient and timely results.

Practicality and applicability: The Mindlin solution exhibits broad applicability in practical engineering problems, offering solutions to various challenges encountered in real-world engineering scenarios.

3. The importance of stress release effect during excavation in the surrounding area lies in ensuring the stability of the soil, structural safety, and stability of the groundwater system, thus ensuring the safety of the construction and the surrounding environment.

The stress release effect during excavation of foundation pits can result in the following anisotropic effects:

Stress Changes: Excavation of a foundation pit causes a redistribution of stresses within the soil. The horizontal stresses decrease, while the vertical stresses increase, leading to different stress responses in different directions.

Deformation Differences: Excavation of a foundation pit induces deformation in the soil, with significant differences in different directions. For example, in the horizontal direction, the soil may experience lateral expansion, while in the vertical direction, settlement or shrinkage may occur.

Permeability Changes: Excavation of a foundation pit can also alter the permeability of the soil. The horizontal permeability may increase, while the vertical permeability may decrease, resulting in different permeability characteristics in different directions.

The conclusions in the literature were supplemented in the article.

4. Yes, detailed modifications and supplements have been made in the paper.

The current research mainly focuses on the deformation effects of adjacent subway tunnels caused by excavation of foundation pits, but there is limited consideration given to the influence of geological conditions related to fault zones.

5. The section in question has been supplemented in the main text, and the boundary conditions used in the modeling include:

Top boundary condition: Typically, the top of the model is set as a free surface boundary condition, allowing for free deformation of the model's top, simulating the deformation and settlement of the soil during actual excavation processes.

Bottom boundary condition: In centrifuge modeling, the bottom boundary condition can be chosen as a fixed boundary condition, where the bottom of the model is set as fixed to simulate the constraints present in the actual situation.

Side boundary condition: The side boundary condition can be chosen as a free boundary condition, allowing for free deformation of the soil on the sides of the model. Alternatively, specific constraint conditions can be set based on the particular circumstances to simulate realistic constraints.

6. The data in Table 1 is derived from the experimental data in the survey report of the project on which this study is based. The report has undergone expert review.
7. Top boundary condition: The top is set as a free surface boundary condition, allowing the soil to undergo free deformation and settlement during the excavation process.

Bottom boundary condition: A fixed boundary condition can be selected for the bottom, fixing the model's bottom to simulate the actual constraint conditions.

Lateral boundary condition: A free boundary condition can be selected, allowing the soil on the sides of the model to undergo free deformation.

We hope that these revisions address your concerns and have strengthened the manuscript. We have also attached a marked-up version of the revised manuscript to this email to show you exactly what changes have been made.

Once again, we appreciate your insightful feedback and the time you have dedicated to reviewing our work. Please let us know if you have any further questions or concerns.

Sincerely,

Yungang Niu

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript titled 'Study on the Influence of Foundation Pit Excavation on the Deformation of 

Adjacent Subway Tunnel in the Affected Area of Fault Zones' encompasses a comprehensive 

investigation into the impact of foundation pit excavation on the deformation of neighbouring 

subway tunnels within fault zones. The authors have undertaken a range of analytical approaches, 

including theoretical analysis, experimental studies, and numerical simulations, to gain a thorough 

understanding of the influence of various geological parameters on tunnel displacement. They have 

also developed a prediction model to forecast tunnel displacement based on excavation and soil 

parameters.

The authors have consolidated significant research within a single article. However, it is worth noting 

that certain sections of the manuscript lack a sufficiently detailed description. To address this 

concern, the following suggestions are proposed to enhance the clarity and comprehensiveness of

each section.

Line No: 12-22: Simplify the statements and end a sentence with a full-stop ".", instead of a semi￾colon ";".

Line No: 40-43: Write the 'research gaps' or the 'need of the research' at the end of the literature 

survey.

Line No: 68: Please check the spelling of Winker. It should be Winkler.

Line No: 81-84: Please, discuss the reason for choosing such sections or refer to the codes used for 

the design.

Line No: 156-157: Only three properties of the soil are given, which is insufficient to classify the soil. 

Add more soil properties (Atterberg's limit, strength properties etc.) and write in a tabular form.

Line No: 161: rainfall simulation - The soil is said to be sandy clay, implying the clay part is more than 

the sand. How can the rainfall simulation be used for clayey soil? 

Did the authors consider dried powdered clay? In that case, the test would be a drained test which is 

unrealistic for clayey soil.

Line No: 167: Mindin - Spelling correction.

Line No: 174: The numerical analysis part is incomplete. The authors should discuss in detail:

a. The material properties used for all the elements.

b. The mesh size and the mesh convergence studies performed to decide the mesh or 

element size.

c. A validation study to prove the reliability of the numerical analysis.

d. Add loadings and their direction in the schematic diagram.

Line No: 179: Why such boundary dimensions are considered? Kindly mention if the authors 

performed any boundary optimisation study.

Line No: 182,183: 2D plate elements, 1D beam elements - What elements are used? What is the 

number of nodes and Gauss points?

Figure 9(a): The letters in axis titles are overlapping and unclear. Please check and clearly write them.

Line No: 219: Please mention the magnitude of the E.

Line No: 231: Please mention the magnitude of the internal friction.

Eq 9: Please check the equation.

Overall, the English writing is good. However, some sentences should be written clearly and some typo should be corrected as suggested.

Author Response

Dear Dr,

Thank you very much for taking the time to review our manuscript entitled "Study on the Influence of Foundation Pit Excavation on the Deformation of Adjacent Subway Tunnel in the Affected Area of Fault Zones". We appreciate your valuable comments and suggestions, which have helped us to improve the quality of our work.

We have carefully considered all of your comments and suggestions, and have made the following revisions to the manuscript:

1. Already modified.
2. Already modified.
3. Already modified.
4. The design data in 81-84 is sourced from the design documentation of the project. The design is based on the specifications of the "Technical Standards for Excavation Support in Shenzhen City" (SJG 05-2020), and the design scheme has undergone expert review.
5. Yes, it has been modified and supplemented in the article.
6. The material name in pages 156-157 should be changed to "Shenzhen Standard Sand" because, after all, the centrifuge experiments were conducted using sand, and it is difficult to conduct centrifuge experiments with sandy cohesive soil. The incorrect description of the material name is a mistake in the main writing work.
7. Already modified.
8. Element properties have been supplemented in Table 2, and other additions have been made in the text. The reliability of the finite element analysis was primarily validated through comparisons with subsequent experimental data.
9. According to the Saint Venant's principle, the influence range of excavation on the surrounding environment is approximately 3 to 5 times the excavation depth. Beyond this range, the deformation of the soil is minimal and can be neglected.
10. The tunnel lining and retaining structures are simulated using shell elements. The column piles, crown beams, waist beams, and support beams are simulated using 1D beam elements. Two-dimensional plate elements are typically represented by quadrilateral elements (such as quadrilateral plane stress elements or quadrilateral plane strain elements) or triangular elements (such as triangular plane stress elements or triangular plane strain elements). As for the two-dimensional beam elements, commonly used types are two-dimensional beam elements (such as plane beam elements or plane beam elements) that are used to simulate beam components in the structure.

Generally, a higher number of nodes leads to a higher accuracy of the model but also increases the computational cost. Taking various factors into consideration, the three-dimensional finite element model in this study consists of approximately 72,000 finite elements.

11. Already modified.
12. The initial values of E, φ, and C can be found in Table 1, and specific additions have been made in the corresponding section of the article to provide further details.
13. Please refer to Table 1 for detailed information.
14. Already modified.

We hope that these revisions address your concerns and have strengthened the manuscript. We have also attached a marked-up version of the revised manuscript to this email to show you exactly what changes have been made.

Once again, we appreciate your insightful feedback and the time you have dedicated to reviewing our work. Please let us know if you have any further questions or concerns.

Sincerely,

Yungang Niu

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have revised the manuscript considering my comments raised during first review. The reviewer is satisfied and this version of paper can be considered for publication.

Author Response

Dear Dr,

I am writing this email to express my deepest gratitude for reviewing my manuscript. I sincerely appreciate the time and effort you took to carefully read and evaluate my work. Your valuable insights and suggestions have been incredibly valuable to me and have provided crucial guidance for my research and writing.

Once again, I want to express my gratitude for your professional critique and recommendations. Your assistance has allowed me to delve deeper into my research and improve the quality of my work. I am truly grateful for your dedication and support, as your contributions hold significant meaning for both me personally and my research endeavors.

Wishing you all the best in your endeavors.

With sincere appreciation,

Yungang Niu

Reviewer 3 Report

The authors have properly incorporated the changes suggested and the manuscript can be accepted in its present form. 

Minor comment: Please add the relative density of the soil, which is a crucial property for a cohesionless soil.

The Engilsh language used is proper and not difficult to understand.

Author Response

Dear Dr,

I am writing this email to express my deepest gratitude for reviewing my manuscript. I sincerely appreciate the time and effort you took to carefully read and evaluate my work. Your valuable insights and suggestions have been incredibly valuable to me and have provided crucial guidance for my research and writing.

We have carefully considered all of your comments and suggestions, and have made the following revisions to the manuscript:

1.Already modified and supplemented.

Rlative density of 1.71

Once again, I want to express my gratitude for your professional critique and recommendations. Your assistance has allowed me to delve deeper into my research and improve the quality of my work. I am truly grateful for your dedication and support, as your contributions hold significant meaning for both me personally and my research endeavors.

Wishing you all the best in your endeavors.

With sincere appreciation,

Yungang Niu

Author Response File: Author Response.pdf