Investigation of Deep Shaft-Surrounding Rock Support Technology Based on a Post-Peak Strain-Softening Model of Rock Mass
Round 1
Reviewer 1 Report
Mine shafts are access excavations that must exist throughout the life of the mine. Therefore, the selection of the lining plays a very important role in ensuring the overall stability of this excavation. The presented calculations and numerical research seem to be important from the scientific and technological point of view. Below are some comments and suggestions:
- In chapter 2.1.2 a few sentences should be added regarding the "Plutons" model (line 150) and more precisely what the term "Plutons" means.
- Lines 206, 207 should remove the pause between the number and the unit.
- In the chapter 4.5 it should be written down how long do the various stages of installing well circle, anchor rods and concrete support take.
- In the chapter 4.10 it should be written what was the accuracy of the performed measurements.
- In the fourth chapter, reference should be made to the discussion of the research results presented in other publications dealing with the measurement of deformation of rock mass.
Author Response
Dear Reviewer:
Thank you very much for your help of our manuscript. We are truly grateful to the comments and suggestions from your review. Based on these comments and suggestions, we have made careful modifications on the manuscript. All the changes made to the text are in red color. You will find our point by point responses to the comments as bellow.
Responses to Reviewer Comments
Point 1: In chapter 2.1.2 a few sentences should be added regarding the "Plutons" model (line 150) and more precisely what the term "Plutons" means.
Response 1: Thanks for the reviewer's comment. We have corrected the meaning of "Plutons" in the resubmitted manuscript, which means "joint rock mass".
Point 2: Lines 206, 207 should remove the pause between the number and the unit.
Response 2: Thanks for reviewer’s comment. We have removed the pause between the number and unit on lines 206 and 207 in the resubmitted manuscript.
Point 3: In the chapter 4.5 it should be written down how long do the various stages of installing well circle, anchor rods and concrete support take.
Response 3: Thanks for reviewer's comment. We have added your suggestions to the resubmitted manuscript. The added content is: In an excavation section, the design time of the bolt structure installation phase comprises two shifts, the installation time of the well circle is one shift, and the installation time of the concrete structure is one shift, with a total of 8 hours per shift. (from L402 to L404)
Point 4: In the chapter 4.10 it should be written what was the accuracy of the performed measurements.
Response 4: Thanks for the reviewer’s comments. According to your suggestion, we have added the accuracy of the performed measurements in this section. (from L581 to L582)
Point 5: In the fourth chapter, reference should be made to the discussion of the research results presented in other publications dealing with the measurement of deformation of rock mass.
Response 5: Thank you reviewers for their comments. Your suggestions are of great help to our work. In the resubmitted manuscript, we revised this part according to your suggestions, and we added relevant discussions on the calculation results. (from L616 to L654)
We sincerely thank the reviewers for their support and contribution to our work. Your valuable opinions are of great help to the improvement of our work. According to your suggestion, we have completed the revision of the paper. We hope that our work can be recognized by you, and we would like to express our gratitude to you again.
Sincerely yours,
Dr. Jianjun Zhang
School of Civil Engineering
Liaoning Technical University
Fuxin 123000, Liaoning, China
Tel.: +86 13898558156
E-mail: zhangjianjun@lntu.edu.cn
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript in the current form is nsuitable for publication in MDPI journal
Author Response
Dear Reviewer:
We sincerely thank you for your support and contribution to our work. Your valuable comments are of great help to the improvement of our work. According to your suggestions, we have made meticulous changes to the manuscript. All changes to the text are marked in red I hope that our work can be recognized by you, and we would like to express our gratitude to you again.
Sincerely yours,
Dr. Jianjun Zhang
School of Civil Engineering
Liaoning Technical University
Fuxin 123000, Liaoning, China
Tel.: +86 13898558156
E-mail: zhangjianjun@lntu.edu.cn
Author Response File: Author Response.pdf
Reviewer 3 Report
Brief Summary
The study aimed at investigating the deep shaft surrounding rock and the softening behavior of the rock mass according to the several theories and a composite support technology is proposed. The latter is then tested on field and found to have promising outcomes. The manuscript is well-written but more work is needed on the structure of the manuscript. However, several aspects need to be addressed by the authors. These are elaborated below.
Major comments
Can the author elaborate on L23 what is meant by ‘stabilizes’? Does this mean that the deformation remains at 140mm? Also, the subsequent sentence makes a comparison in percentage which is difficult to follow, can the equivalent deformation in millimeter be reported instead?
The authors elaborate several studies from L47 to L78. However, these descriptions appear to be superficial. For instance, L71: Yu et al. solved the problem of large deformation – what were the outcomes? How does it compare to other studies? What is unique about this particular study? These are to be addressed and framed in the context of the current study.
The limitations described on L84 need to be described. The question: ‘Why is strain softening mechanical behavior needed?’ should be answered more explicitly by the authors.
Which studies are being referred to on L89? These need to be stated to determine how novel the current study is.
From Figure 6, why is it that the model better describes the elastic region than the plastic region? What are the causes for deviation of Test to Model?
Section 4 has several elements which should be introduced in the ‘background section’. For example, the description of shaft excavation needs to be introduced earlier if this is to be included in the manuscript. A lot of general information appears in the different subsection which needs to be placed in a ‘Section 2’ labelled background.
Can the authors also compare the reasons described on L476 to other studies geared towards similar investigations?
On L602, in the conclusions section the authors need to include data to support the ‘more realistic’ nature of the model compared to existing ones.
Minor but still important comments that should be addressed
L16: …to release…
L56: The authors need to elaborate on the 3DEC-trigon method and how it differs from other techniques.
L103: ‘GSI’ need to be spelled out
L123: What is troublesome? The authors need to specify how the subsequent empirical relationships (e.g. eqn (4) make the numerical task less troublesome)
L210: Are the sizes reported and aspect ratio mentioned of the samples performed as per any guidelines/standards?
L355: A better sub-section description is needed here.
L522: Can the authors also include the original design scheme parameters so that the changes via the optimized support can be better compared?
L570: Can the calculation results be included in Fig 14 so as to better compare the original and optimized conditions?
L619: The term ‘good’ here should be relative to existing designs.
Author Response
Dear Reviewer:
Thank you very much for your help of our manuscript. We are truly grateful to the comments and suggestions from your review. Based on these comments and suggestions, we have made careful modifications on the manuscript. All the changes made to the text are in red color. You will find our point by point responses to the comments as bellow.
Responses to Reviewer Comments
Point 1: Can the author elaborate on L23 what is meant by ‘stabilizes’? Does this mean that the deformation remains at 140mm? Also, the subsequent sentence makes a comparison in percentage which is difficult to follow, can the equivalent deformation in millimeter be reported instead?
Response 1: Thanks for reviewer’s comment. Your suggestions are of great help to our work. According to your suggestions, we have revised this part of the resubmitted manuscript. Here, " stabilizes " means “shaft rock deformation No more deformation after reaching 140mm", and the percentage "53.3%" has been replaced with a millimeter equivalent deformation.
Point 2: The authors elaborate several studies from L47 to L78. However, these descriptions appear to be superficial. For instance, L71: Yu et al. solved the problem of large deformation – what were the outcomes? How does it compare to other studies? What is unique about this particular study? These are to be addressed and framed in the context of the current study.
Response 2: Thanks for the reviewer's comment. In the resubmitted manuscript, we have detailed the content and optimized the structure of this part.
Point 3: The limitations described on L84 need to be described. The question: ‘Why is strain softening mechanical behavior needed?’ should be answered more explicitly by the authors.
Response 3: Thanks for reviewer’s comment. We revised this part of the resubmitted manuscript, and clarified the reason and significance of studying the mechanical behavior of rock mass strain softening in the article. (from L90 to L96)
Point 4: Which studies are being referred to on L89? These need to be stated to determine how novel the current study is.
Response 4: Thanks for reviewer’s comment. "Previous studies" here refer to the studies in L48-L88, which we have revised to avoid ambiguity.
Point 5: From Figure 6, why is it that the model better describes the elastic region than the plastic region? What are the causes for deviation of Test to Model?
Response 5: Thanks for reviewer’s comment. In the model proposed in this paper, the difference between the maximum principal plastic strain and the minimum principal plastic strain is defined as the softening parameter of the rock mass. When the experimental rock mass is in the elastic deformation stage, the rock mass does not produce plastic strain, and the rock mass softening parameter is 0. The mb and s in the constants in the Hoek-Brown yield criterion have not decayed. Therefore, in the elastic stage, the model curve and the test curve also achieve a better fit. The model curve is the result of numerical calculation under ideal conditions, and the laboratory experimental rock block is taken from the mining area. The mining area has developed faults and the surrounding rock is broken to a large extent. There are fissures in the actual experimental rock sample, which results in deviation.
Point 6: Section 4 has several elements which should be introduced in the ‘background section’. For example, the description of shaft excavation needs to be introduced earlier if this is to be included in the manuscript. A lot of general information appears in the different subsection which needs to be placed in a ‘Section 2’ labelled background.
Response 6: Thanks for reviewer’s comment. We optimized the structure of the resubmitted manuscript and placed the description of the shaft excavation in the background marked "Section 2". (from L223 to L285)
Point 7: Can the authors also compare the reasons described on L476 to other studies geared towards similar investigations?
Response 7: Thanks for reviewer’s comment. We have added a comparison with other similar studies in the resubmitted manuscript. Among the reasons for the large deformation of the rock mass and the failure of the supporting structure, we collectively believe that the rock mass is not closed in time and causes the weathering of the rock mass. Water softening and high ground stress are the reasons for the large deformation of the surrounding rock and the failure of the supporting structure. In addition, we believe that the shaft excavation footage is too large, and the initial support rigidity is too large, resulting in insufficient release space for the surrounding rock stress, which is also the cause of the large deformation of the surrounding rock and the failure of the supporting structure. (from L507 to L516)
Point 8: On L602, in the conclusions section the authors need to include data to support the ‘more realistic’ nature of the model compared to existing ones.
Response 8: Thanks for reviewer’s comment. We added relevant supporting data in the conclusion part of the resubmitted manuscript. (from L656 to L685)
Point 9: L16: …to release…
Response 9: Thanks for reviewer’s comment. We corrected this error in the resubmitted manuscript.(on L16)
Point 10: L56: The authors need to elaborate on the 3DEC-trigon method and how it differs from other techniques.
Response 10: Thanks for reviewer’s comment. We have rewritten this part in the resubmitted manuscript.
Point 11: L103: ‘GSI’ need to be spelled out
Response 11: Thanks for reviewer’s comment. We spelled out the full name of ‘GSI’ in the resubmitted manuscript, namely ‘Geological Strength Index’.（on L111）
Point 12: L123: What is troublesome? The authors need to specify how the subsequent empirical relationships (e.g. eqn (4) make the numerical task less troublesome)
Response 12: Thanks for reviewer’s comment. Here, what we think is that the usual way to obtain the GSI value is to obtain the GSI value corresponding to the rock mass by querying the GSI quantification table based on the block volume Vb and the structural plane condition factor JC. The “troublesome” mentioned here means “the method of obtaining the GSI value of the rock mass by querying the GSI quantification table generally cannot obtain the accurate GSI value of the rock mass. Different people may choose different GSI values within this range, so this method is likely to cause errors in subsequent numerical calculations.” For equation (4), when the block volume Vb and the structural plane condition factor JC are determined, The GSI value is uniquely determined, which avoids errors and makes the numerical calculation results more reliable.
Point 13: L210: Are the sizes reported and aspect ratio mentioned of the samples performed as per any guidelines/standards?
Response 13: Thanks for reviewer’s comment. The size and aspect ratio of the sample are executed in accordance with the standard: DZ/T 0276.20-2015, Regulation for testing the physical and mechanical properties of rock—Part 20: Test for determining the strength of rock in triaxial compression[S], we are renewing Add the relevant content of the standard to the main text and references in the submitted manuscript. (on L295)
Point 14: L355: A better sub-section description is needed here
Response 14: Thanks for reviewer’s comment. We have rewritten this part of the content in the resubmitted manuscript based on the engineering survey data, and improved the engineering background information. (from L368 to L386)
Point 15: L522: Can the authors also include the original design scheme parameters so that the changes via the optimized support can be better compared?
Response 15: Thanks for reviewer’s comment. We revised this table in the resubmitted manuscript. In order to better compare the difference between the optimized support plan and the original support plan, we included the original support plan parameters together in the optimized support plan table (Table 8,on L547).
Point 16: L570: Can the calculation results be included in Fig 14 so as to better compare the original and optimized conditions?
Response 16: Thanks for reviewer’s comment. Sorry that we failed to optimize this picture. We used the convergence-constraint method to present the calculation results of the original support plan and the optimized support plan in Figure 11 and Figure 13, respectively. We compared and analyzed the two based on Figure 11 and Figure 13. The accuracy of the similar calculation results and the reasons for the errors were obtained. Finally, the results of on-site surrounding rock deformation monitoring were used to verify our analysis. Therefore, we put Figure 14 alone at the end. This is our idea.
Point 17: L619: The term ‘good’ here should be relative to existing designs.
Response 17: Thanks for reviewer’s comment. We revised this part in the resubmitted manuscript.
We sincerely thank the reviewers for their support and contribution to our work. Your valuable opinions are of great help to the improvement of our work. According to your suggestion, we have completed the revision of the paper. We hope that our work can be recognized by you, and we would like to express our gratitude to you again.
Sincerely yours,
Dr. Jianjun Zhang
School of Civil Engineering
Liaoning Technical University
Fuxin 123000, Liaoning, China
Tel.: +86 13898558156
E-mail: zhangjianjun@lntu.edu.cn
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The authors have addressed my initial comments.
