Structural Stability and Surrounding Rock Integrity Analysis for Goaf-Side Entry with Small Coal Pillars in Longwall Mining
Round 1
Reviewer 1 Report
To the Authors,
The presented research is interesting for the engineers in the coal mining industry and it is well-conceived.
However, there are two issues that must be resolved.
1. Statement in Chapter 1. (lines, 34, 35, 36): "A small coal pillar..." is not supported with appropriate reference(s), and as such is more likely to be a hypothesis than a statement. Also, it contradicts the findings provided in chapter 2.2 (lines 142-145) "Under the action..." which suggests the presence of secondary cracks in small coal pillar. Cracks are indicators of pillar failure and such pillar can not be considered as reliable isolation regarding air leakage toward the goaf. Recommendation: delete the sentence "A small coal pillar..." (lines 34, 35, 36).
2. Presence of "Immediate roof" seam is evident in Figure 1 and Figure 2. However, the impact of the "Immediate roof" on the model is completely disregarded, although it is positioned between Block B and the coal pillars. It should be noted that all vertical forces are transferred through the Immediate roof. Chapter 2 must be complemented with an explanation for this approach. The explanation must provide the reasoning for excluding the immediate roof from the model.
Chapter title (line 124) - numbering - it should be 2.1 instead of 3.1.
Author Response
Dear Reviewer,
Thank you very much for your timely review and insightful suggestions. The authors have Addressed all the reviewers’ comments and revised the manuscript correspondingly.
Best regards,
Yiming
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comment 1.
The present manuscript present a technology called goaf-side entry with small coal pillars (GESCP), which is used in underground coal mines in China to improve coal recovery ratio. The paper investigates the critical condition of the main roof failure above the solid coal side of goaf-side entry and identifies the key parameters that affect the structural stability of the surrounding rocks for GESCP. The research findings suggest that the integrity of the coal sidewalls plays a major role in maintaining the structural stability of surrounding rock for GESCP, and enhancing the strength of the supporting coal side walls and ensuring the integrity of the small coal pillars are important factors for achieving structural stability. The conclusions were verified by engineering practice at a coal mine in China.
The research findings suggest that enhancing the strength of the supporting coal side walls and ensuring the integrity of the small coal pillars are important factors for achieving structural stability. Moreover It contributes to the understanding of the critical conditions of the main roof failure above the solid coal side of goaf-side entry and investigates the key parameters that affect the structural stability of the surrounding rocks for GESCP.
Overall, this research has important implications for the safety, efficiency, and sustainability of underground coal mining, which is a critical industry for many countries around the world. A manuscript has a practical application and also provides important theoretical for the next studies. The paper can be accepted for publication after providing the corrections mentioned below.
Comment 2.
Lines 39-87. Subdivide into several paragraphs.
Comment 3.
The paper could be challenging to comprehend, and it would be helpful if the authors had structured it using the conventional IMRaD format, which is widely known. By explicitly outlining the Methods, Results, and Discussion sections, the study could have followed a more traditional pattern that would make it easier for readers to grasp the main points of the manuscript.
Comment 4.
Line 85. Reference [30] is not given in the reference list.
Comment 5.
The Introduction section of the paper needs to include a more comprehensive literature review. The authors have cited only 20 sources, which is insufficient for the scope of this research. It would be beneficial if the authors provided additional context to explain the significance of their study and highlighted the limitations of their research. This would help readers better understand why this study is important and the boundaries of the study's conclusions.
Comment 6.
When expanding the Introduction section with additional literature review, please take into account the suggested research from Ukraine and Vietnam. These studies may provide valuable insights that could enhance the overall quality of your paper.
Dychkovskyi, R.; Shavarskyi, Ia.; Saik, P., Lozynskyi, V.; Falshtynskyi, V.; Cabana, E. Research into stress-strain state of the rock mass condition in the process of the operation of double-unit longwalls. Mining of Mineral Deposits, 2020, 14, 85-94. Doi:10.33271/mining14.02.085
Vu, T.T. Solutions to prevent face spall and roof falling in fully mechanized longwall at underground mines, Vietnam. Min. Miner. Depos. 2022, 16, 127-134. Doi:10.33271/mining16.01.127
Shavarskyi, Ia.; Falshtynskyi, V.; Dychkovskyi, R.; Akimov, O.; Sala, D.; Buketov, V. Management of the longwall face advance on the stress-strain state of rock mass. Mining of Mineral Deposits, 2022, 16, 78-85. https://doi.org/10.33271/mining16.03.078
Comment 7.
Figure 2 and 3. Please explain all symbols.
Comment 8.
Line 138. The subsection can not be end by formula. Please add descriptions of above mentioned.
Comment 9.
Please provide answers for four important questions and provide lines where it is discussed:
- What mechanical models were used to establish the main roof and multi-layer-cracking structures of the side wall of GESCP for the structural stability analysis?
- How were the key parameters affecting the main parameters of structural stability of the surrounding rock analyzed in this research?
- How was the proposed limiting equilibrium equation for the structural stability of the surrounding rock derived and what assumptions were made in its development?
Comment 10.
Sketch of initial combined bolt–mesh–cable support (Figure 12) is presented quite well. At the same time Sketch of revised combined bolt–mesh–cable support (Figure 13) is difficult to understand as formatting is very poor.
Comment 11.
Discuss the support effected in the haulage gateway (Figure 14) in more detail.
Comment 12.
It would be beneficial if the paper also explored the impact of leaving rock underground after coal mining on the Damage Evolution Law. It is worth considering the research mentioned below, as it could influence the direction of future research. This additional information could provide a more comprehensive understanding of the factors that affect Damage Evolution Law and may have implications for the design and operation of coal mines.
Smoliński, A.; Malashkevych, D.; Petlovanyi, M.; Rysbekov, K.; Lozynskyi, V.; Sai, K. Research into Impact of Leaving Waste Rocks in the Mined-Out Space on the Geomechanical State of the Rock Mass Surrounding the Longwall Face. Energies, 2022, 15, 9522. https://doi.org/10.3390/en15249522
Malashkevych, D.; Petlovanyi, M.; Sai, K.; Zubko, S. Research into the coal quality with a new selective mining technology of the waste rock accumulation in the mined-out area. Min. Miner. Depos. 2022, 16, 103-114. https://doi.org/10.33271/mining16.04.103
Comment 13.
Please provide a brief overview of the proposed future research.
Comment 14.
Overall, I must say that this is a well-conducted study, and I would recommend that it be published after a thorough revision. With some improvements and clarifications, this research could make a significant contribution to the field and be of interest to a wide range of readers.
Author Response
Dear Reviewer,
Thank you very much for your timely review and insightful suggestions. The authors have Addressed all the reviewers’ comments and revised the manuscript correspondingly.
Best regards,
Yiming
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Maybe a not final version of the paper was attached because there is a lot of misconduct between the authors' reply and the real text within the paper.
Reply 2
Once more - please avoid a long paragraph.
You have added lines 49-71. It is huge.
It must be subdivided using understandable principles of the Introduction presentation.
Must be revised.
Reply 3
Why do not do it within this paper?
Must be revised.
Reply 5
Why authors used predominantly literature published by authors from China?
It is a bad practice not to provide more wide literature review?
What is going on with research abroad in China in this direction?
Must be revised.
Reply 6
These references were suggested to you the reason to use them in your research and add to the reference list to avoid the situation that only researchers from China make research in Mining.
Mining is developed in different countries and a number of different research is conducted regularly.
Also, I can not find mentioned (suggested) papers in the reference list.
Must be revised.
Reply 9
Authors provide replies to comments but do not indicate where it is discussed in the paper.
Please provide step by step explanation of where it can be found.
Must be revised.
Reply 11
The authors added only two full lines. More detail is required.
Must be revised.
Reply 12
Authors indicate that it was considered but the suggested papers were not considered at all.
There is no discussion here according to comment 12.
Also I can not find mentioned papers in the reference list.
Must be revised.
Reply 13
The description of further research must be discussed before the Conclusion section, not here.
Providing a brief overview of the proposed future research enhances the clarity, context, and credibility of the current research paper. It allows readers to grasp the research's significance, direction, and potential impact, while also promoting transparency and accountability in the scientific process.
A brief overview of proposed future research in a research paper is necessary because it provides context and relevance to the current research, clarifies the direction and focus of the work, discusses potential methods and techniques to be used and acts as a roadmap for future studies.
Must be revised.
Reply 14
Most suggestions were not considered at all. Several need to be revised once more.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer,
Thank you very much for your timely review and insightful suggestions. The authors have addressed all the reviewers’ comments and revised the manuscript correspondingly.
Best regards
Yiming
Author Response File: Author Response.docx
Round 3
Reviewer 2 Report
Dear authors,
The current version of the revision is well presented.
My congratulations.
