Pattern of Influence of the Mining Direction of the Protective Seam on the Stress of the Surrounding Rock
Round 1
Reviewer 1 Report
In this paper, a numerical calculation model is established by using FLAC3D software, and the distribution and evolutionary law of the three-dimensional stress and displacement of the stope under the circumstance that the mining direction of the protective seam is parallel to the maximum principal stress of the primary rock and vertical mining is studied. The writing of the paper is standardized, but lacks innovation. It is recommended to reject the paper for the following specific reasons:
(1) The paper focuses on the influence of the mining direction of the protective layer on the stress of the surrounding rock, but the relevant conclusions are obvious and do not require excessive research.
(2) The paper studied the distribution and evolutionary law of the three-dimensional stress and displacement of the stope, which is relatively shallow and lacks quantitative analysis and mechanism analysis.
Minor editing of English language required
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dynamic phenomena such as coal and gas outburst are the most dangerous from the point of view of coal mine safety.
The most effective way to reduce the risk of these dynamic phenomena is to relaxe the massif by mining a protective coal seam, located in the vicinity of the protected coal seams.
The objective of the research summarized in this article is the study of the influence of the exploitation of the protective coal seam D5-6 on the reduction of the risk of mining of the coal seams E8 and E9-10, from Pingdingshan No. 8 Coal Mine, using numerical modeling with FLAC 3D finite difference software.
The simulations were carried out under the conditions of the mining direction of the protective coal seam, parallel and vertical to the maximum principal stress direction of the original state of stress.
Although the distance from the protective coal seam to the protected seams is 88m and does not comply with the Chinese standards, the tests have shown that the D5-6 seam can be a protective coal seam under conditions where the mining direction is parallel to the maximum natural main stresses.
The scientific arguments brought after the analysis of the numerical results, respectively the stress-strain state, confirm the formation of a zone with „pressure relief”, specific to the influence of a protective coal seam.
The paper is very well written, the content is clearly expressed and the obtained results well analyzed, to highlight the primary objective of the research.
I would like to note that the notions of „parallel mining” and „vertical mining” are not very clear, so I suggest introducing two schemes for clarification.
I also suggest the introduction in the text of the article of some characteristics of the coal seams that highlight their predisposition to the occurrence of these dynamic phenomena, the type of gas, the relative flow rate, the pressure, etc.
I noticed two minor drafting errors:
-in Fig.2b-„ming” must be corrected with „mining”;
- on the scales in Fig.3 and Fig.6, the units of measure (MPa) must be written.
In conclusion, the article is very interesting, both from a theoretical and applied point of view, and I propose to publish it.
Comments for author File: Comments.pdf
Dynamic phenomena such as coal and gas outburst are the most dangerous from the point of view of coal mine safety.
The most effective way to reduce the risk of these dynamic phenomena is to relaxe the massif by mining a protective coal seam, located in the vicinity of the protected coal seams.
The objective of the research summarized in this article is the study of the influence of the exploitation of the protective coal seam D5-6 on the reduction of the risk of mining of the coal seams E8 and E9-10, from Pingdingshan No. 8 Coal Mine, using numerical modeling with FLAC 3D finite difference software.
The simulations were carried out under the conditions of the mining direction of the protective coal seam, parallel and vertical to the maximum principal stress direction of the original state of stress.
Although the distance from the protective coal seam to the protected seams is 88m and does not comply with the Chinese standards, the tests have shown that the D5-6 seam can be a protective coal seam under conditions where the mining direction is parallel to the maximum natural main stresses.
The scientific arguments brought after the analysis of the numerical results, respectively the stress-strain state, confirm the formation of a zone with „pressure relief”, specific to the influence of a protective coal seam.
The paper is very well written, the content is clearly expressed and the obtained results well analyzed, to highlight the primary objective of the research.
I would like to note that the notions of „parallel mining” and „vertical mining” are not very clear, so I suggest introducing two schemes for clarification.
I also suggest the introduction in the text of the article of some characteristics of the coal seams that highlight their predisposition to the occurrence of these dynamic phenomena, the type of gas, the relative flow rate, the pressure, etc.
I noticed two minor drafting errors:
-in Fig.2b-„ming” must be corrected with „mining”;
- on the scales in Fig.3 and Fig.6, the units of measure (MPa) must be written.
In conclusion, the article is very interesting, both from a theoretical and applied point of view, and I propose to publish it.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 3 Report
Review report:
- As the consequences of the outburst were not discussed in the paper, it seems that the expression “outburst risk” is incorrect. It is suggested to use “outburst occurrence” or “outburst potential” instead of “outburst risk”.
- In line 61 it is mentioned that “The conclusions of this paper are conducive to optimizing mining deployment …”. It should be mentioned how the results of the paper can optimize the mining operation and development.
- Literature survey is the main concern of this paper. The past related paper must be presented and discussed in the introduction section.
- The innovation of the paper should be discussed.
- Specification of the model and the mechanical properties of the coal and country rock should be presented.
- Fig. 4 needs to be clarified and explained.
- Lines 226-232 are the research method and should be moved to the research methodology section.
- The technical specifications of the studied mine including the location of the mine, and mechanical properties of the coal and country rock need to be mentioned.
- What is the meaning of Smax and qmax in Fig. 11?
- It should be explained that how to determine the critical values in Fig. 11
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Reviewer 4 Report
This paper explores how the direction of mining a protective seam in a coal mine affects the safety and outburst prevention. Using computer simulations, the study focuses on a specific coal mine and examines the stress and displacement patterns when mining the protective seam parallel or vertical to the original rock's main stress direction. The findings reveal that parallel mining reduces outburst risks by decreasing stress, while vertical mining increases risks. The paper suggests that parallel mining enhances both safety and outburst prevention by reducing stress. This conclusion is validated through real-world case studies. Overall, the research helps improve mine safety by optimizing mining strategies to minimize outburst risks.
This research is important because it demonstrates how the direction of mining a protective seam in relation to the rock's stress direction significantly impacts outburst risks and offers insights for enhancing mine safety.
The paper can be recommended for publication after revision. To enhance the manuscript, the authors should consider incorporating the following revisions:
ü Provide a more detailed explanation of the methodology used for numerical simulations.
ü Clarify the specific parameters and conditions of the Pingdingshan No. 8 Coal Mine in the study.
ü Include additional discussion on potential limitations and uncertainties of the simulation model.
ü Elaborate on the practical implications of the research findings for mine safety and outburst prevention.
ü Consider adding comparisons with relevant studies or real-world data to further validate the conclusions.
While the Introduction section offers an extensive literature review mainly centered around Chinese research, it falls short in adequately analyzing studies from beyond China, highlighting the need for substantial enhancement to achieve a more balanced perspective.
It would greatly enhance the paper if the authors provided contextual reasoning for the significance of conducting this study and addressed the limitations inherent in their research.
What about the influence of leaving rock underground after coal mining? Can such actions make influence of the mining direction of the protective seam on the stress of the surrounding rock? Please consider mentioned below research in your study as it can affect further research direction.
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
Can you explain in your research how parallel mining demonstrated a more favorable impact on reducing the outburst risk of the protective seam and why it was more effective than vertical mining?
How did the research validate the conclusion about the enhanced safety and outburst prevention effect of parallel mining, and how might these findings be applied in practical mine layout optimization to minimize outburst risks?
Upon successful incorporation of the suggested revisions, this paper is likely to receive a recommendation for publication.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The author has carefully revised according to the requirements and the paper is recommended to be accept in present form.
Reviewer 3 Report
All comments were considered. The paper is acceptable in present form.
Reviewer 4 Report
Good revision. I wish the authors all the best in the future research!
