Study on the Influence of Roadway Structural Morphology on the Mechanical Properties of Weakly Cemented Soft Rock Roadways
Round 1
Reviewer 1 Report
This manuscript carries out the study on the influence of roadway structural morphology on the mechanical properties of weakly cemented soft rock road-ways. However, there are many vague nouns and grammatical problems in the text, and the adopted method are not clearly explained. My comments are as follows:
1. The lack of line numbers in the manuscript caused inconvenience to the review of the manuscript.
2. Introduction: The description of “Domestic and foreign scholars have proposed……” is not appropriate and rigorous. As this paper is not published in Chinese journal, the expression of “domestic” and “foreign” will cause misunderstanding.
3. Section 2.3 “……, and 12.2 MPa stress is applied at the top of model, which is equivalent to the self-weight of the overburden rock, ρgh = 2.5 × 10 × 488 Pa = 12.2 MPa”: The buried depth of the roadway structure is 488m, which is a typical deep buried structure. It is not reasonable to use “ρgh” to calculate the vertical stress.
4. Section 3.2: please provide a clear definition of stress concentration coefficient. How it is calculated? Please clarify.
5. Section 3.2: The different of stress peak and concentration coefficient between retaining top or bottom coal of roadway is not obvious. I do not agree the conclusion “that the retaining coal way can change the stress environment of the surrounding rock” from the perspective of stress characteristics of surrounding rock.
6. Section 3.4 “plastic failure area of retaining top coal range is slightly larger”: The “top coal” should be corrected by “bottom coal” according to the following analysis.
7. Section 4: please indicate whether the numerical model in this section retains top or bottom coal.
8. Section 4.3: The sentence “When the aspect ratio of the roadway is small, …, which is conducive to the stability of the roof and floor of the roadway.” is too long, which caused great inconvenience to understanding.
9. Conclusion: The conclusion (1) contradicts with the analysis in section 3. In section 3, author indicates “When retaining top coal, the influence range of vertical displacement of the roof is larger” and “when retaining bottom coal, the influence range of vertical displacement of the floor is larger”. However, in the conclusion (1), “When changing from retaining the top coal to retaining the bottom coal, …, the vertical displacement influence range of the roof and floor becomes smaller”
10. Conclusion: In conclusion (3), the author argued “the reasonable retaining top or bottom coal and roadway aspect ratio can prevent the deformation and failure of weakly cemented soft rock roadway”. However, from the perspective of the calculation results in this paper, the difference of different structural morphology is not significant. It is difficult convince readers that these changes will “prevent” the failure of roadway.
Author Response
Response to Reviewer 1 Comments
Point 1：The lack of line numbers in the manuscript caused inconvenience to the review of the manuscript.
Response 1: The line number and page number are added to our manuscript, and the line number format is continuous.
Point 2：Introduction: The description of “Domestic and foreign scholars have proposed……” is not appropriate and rigorous. As this paper is not published in Chinese journal, the expression of “domestic” and “foreign” will cause misunderstanding.
Response 2: The expression of “domestic” and “foreign” have been deleted.
Point 3：Section 2.3 “……, and 12.2 MPa stress is applied at the top of model, which is equivalent to the self-weight of the overburden rock, ρgh = 2.5 × 10 × 488 Pa = 12.2 MPa”: The buried depth of the roadway structure is 488m, which is a typical deep buried structure. It is not reasonable to use “ρgh” to calculate the vertical stress.
Response 3: This part is reorganized and revised, and the relevant references are supplemented in our manuscript.
Point 4： Section 3.2: please provide a clear definition of stress concentration coefficient. How it is calculated? Please clarify.
Response 4: In rock mechanics, the ratio of secondary stress to primary stress after roadway opening is usually defined as the stress concentration coefficient at this point. Relevant explanations are added in section 3.2 of our manuscript.
Point 5：Section 3.2: The different of stress peak and concentration coefficient between retaining top or bottom coal of roadway is not obvious. I do not agree the conclusion “that the retaining coal way can change the stress environment of the surrounding rock” from the perspective of stress characteristics of surrounding rock.
Response 5: In our manuscript, the stress concentration coefficient refers to the stress concentration coefficient at the peak stress. From the point of view of stress, the peak stress and stress concentration coefficient are reduced slightly, while the area of high stress area is greatly reduced. Therefore, the authors thinks that changing the way of retaining top and bottom coal can improve the stress environment of roadway. The above problems are supplemented and modified in this manuscript.
Point 6：Section 3.4 “plastic failure area of retaining top coal range is slightly larger”: The “top coal” should be corrected by “bottom coal” according to the following analysis.
Response 6: This part of the content is reorganized, and from the point of view of stress transfer explain the reasons for the better stability of the surrounding rock of retaining bottom coal.
Point 7：Section 4: please indicate whether the numerical model in this section retains top or bottom coal.
Response 7: In Section 4, the numerical simulation adopts the method of retaining bottom coal, and relevant explanations are added in the manuscript.
Point 8：Section 4.3: The sentence “When the aspect ratio of the roadway is small, …, which is conducive to the stability of the roof and floor of the roadway.” is too long, which caused great inconvenience to understanding.
Response 8: Reorganized and revised the sentence in our manuscript.
Point 9：Conclusion: The conclusion (1) contradicts with the analysis in section 3. In section 3, author indicates “When retaining top coal, the influence range of vertical displacement of the roof is larger” and “when retaining bottom coal, the influence range of vertical displacement of the floor is larger”. However, in the conclusion (1), “When changing from retaining the top coal to retaining the bottom coal, …, the vertical displacement influence range of the roof and floor becomes smaller”
Response 9: By comparing the two texts, it is found that the Conclusion summary is not accurate enough, and the conclusion is reorganized and revised.
Point 10：Conclusion: In conclusion (3), the author argued “the reasonable retaining top or bottom coal and roadway aspect ratio can prevent the deformation and failure of weakly cemented soft rock roadway”. However, from the perspective of the calculation results in this paper, the difference of different structural morphology is not significant. It is difficult convince readers that these changes will “prevent” the failure of roadway.
Response 10: The description here is not accurate enough, " prevent the deformation and failure of weakly cemented soft rock roadway " has been changed to "reduce the deformation of weakly cemented soft rock roadway ".
Reviewer 2 Report
This manuscript presents a numerical study on the influence of roadway structure shape on the mechanical responses of weakly cemented soft rock roadways. The analytical method, data, and results are presented clearly and the conclusions are supported by the results presented.
The manuscript may be considered for publication after the following comments are addressed:
1. The manuscript contains a moderate level of errors in grammar, format, and punctuation. Since the manuscript does not have line numbers, I did not list the details of these errors, but highlighted them in the PDF file. The manuscript needs to be proofread and revised to correct these errors.
2. In the Introduction section, the review of a body of literature (26 references) is loosely connected to the research objective of this study. I cannot see strong justification of the proposed research objective from the literature review. I suggest the authors reorganize the literature with more critique of existing work instead of simply stating what have been done in the literature.
3. Please explain what the lines and different colors represent in Figure 1.
4. What type of model is the numerical calculation model as stated in the last line of Page 5?
5. What type of stress is presented in Figure 6? vertical normal stress? What is the unit of the stress? Same comment goes to Figure 7 and other figures.
6. I see that later on Page 7, the authors mentioned that the software FLAC3D was used in the analysis. More details of the software should be given. The validity of this software for analyzing the roadways in this study should be discussed.
Comments for author File: 
Comments.pdf
Author Response
Response to Reviewer 2 Comments
Point 1：The manuscript contains a moderate level of errors in grammar, format, and punctuation. Since the manuscript does not have line numbers, I did not list the details of these errors, but highlighted them in the PDF file. The manuscript needs to be proofread and revised to correct these errors.
Response 1: The line number and page number are added to our manuscript, and the line number format is continuous. The manuscript has been carefully checked and the details you raised have been revised.
Point 2：In the Introduction section, the review of a body of literature (26 references) is loosely connected to the research objective of this study. I cannot see strong justification of the proposed research objective from the literature review. I suggest the authors reorganize the literature with more critique of existing work instead of simply stating what have been done in the literature.
Response 2: The Introduction section was reorganized and summarized the influencing factors, which provides a research basis for this paper to study the influence of structural morphology of weak cemented soft rock roadway on mechanical properties.
Point 3：Please explain what the lines and different colors represent in Figure 1.
Response 3: Figure 1 is modified and explained in the manuscript. Specifically, black represents the boundary of roadway and mine boundary, and red represents folds and faults.
Point 4：What type of model is the numerical calculation model as stated in the last line of Page 5?
Response 4: The numerical calculation model is a 3D model. The relevant information about the model is added in our manuscript and more detail is seen in Figure 4.
Point 5：What type of stress is presented in Figure 6? vertical normal stress? What is the unit of the stress? Same comment goes to Figure 7 and other figures.
Response 5: Figure 6 showed the vertical stress cloud diagram (unit: Pa). Figure 7 is the vertical displacement cloud diagram (unit: m). Figure 9 is available for vertical stress cloud diagram and Figure 10 for vertical displacement cloud diagram. All the four graphs were modified, and the graph names and units were marked.
Point 6：I see that later on Page 7, the authors mentioned that the software FLAC3D was used in the analysis. More details of the software should be given. The validity of this software for analyzing the roadways in this study should be discussed.
Response 6: The three-dimensional model and the sources of plane model established in our manuscript were supplemented. More details see Figure 4.
Reviewer 3 Report
Hi Authors
Thanks for submitting the manuscript to MDPI sustainability.
Sorry as there are no line numbers in manuscript so I pick the sentences. Pls see the highlighted / colored text as queries.
Abstract
1. If the bottom coal is retained, the stress, deformation and plastic zone of weakly cemented soft rock roadway show a decreasing trend- Pls quantify?
2. if the aspect ratio of the roadway is changed by the equal area method - Pls quantify?
3. So the reasonable retaining coal mode and the aspect ratio of the roadway can prevent the deformation and failure of the weakly cemented soft rock roadway - Can you pls quantify?
Pls revisit and try to incorporate few keywords of this special issue in title, abstract and text i.e.
- deep mining
- soft rock support
- surrounding rock control
- support technology and equipment
- design and evaluation of support system
Keywords: Structural morphology of roadway; weakly cemented soft rock. Pls revisit?
Introduction
1. The weakly cemented soft rocks of the Triassic, Cretaceous, and Jurassic are widely distributed in the western regions of Xinjiang, Gansu, Ningxia, and Western Inner Mongolia in China - Can you pls add a Map as Figure showing the distribution zoning?
2. From the perspective of disaster management,- Pls enter the reference
3. Therefore, the reasonable layout of roadway shape is explored from the root of stress, so as to prevent and control the deformation and failure of weakly cemented soft rock roadway - How Authors can give such statement in Introduction? Can be in your methodology ? Kindly revisit?
4. Can you pls enter some notable Figures or tables from references mentioned from 1 to 25 especially from some domestic scholars? This will uplift the background portion a lot?
From the perspectives of theoretical research, laboratory experiment, similar simulation, numerical calculation and industrial experiment, scholars have carried out corresponding research on the damage and failure of weakly cemented soft rock and the deformation control technology of surrounding rock, and obtained fruitful research results from the control technology of weakly cemented soft rock roadway - Can you share some? This will be the grounds of your problem statement.
Figure 1 please label
Due to the influence of factors such as large buried depth, high ground stress, poor lithology and rich floor water.... Pls add reference
In August 2020, after the temporary suspension of mining at 11303 working face, the bearing capacity of the roadway support was significantly reduced (Can you specify the quantity ?), and the deformation of the roadway was further aggravated (Can you specify the quantity ?), which led to the failure of the support body and the phenomenon of coal wall caving, floor heave and side shrinkage at the working face, which is very likely to induce roof and floor disaster accidents and significantly increase the degree of safety risk. Reference Pls.
Through the lithological analysis and mechanical properties, Can you enter a table of these values?
The action of high stress (Can you specify the quantity ?) serious rheological deformation (Can you specify the quantity ?), resulting in the working face back mining roadway deformation increased (Can you specify the quantity ?) sharply, the......
For the deformation and failure of the roadway, the preliminary analysis found that the floor is sandy sandstone, which is a weak floor, and the floor is the release port of stress or energy under the excavation -- Can you introduce an excavation section labelling different layers ?
where the x-axis is the coal seam tendency, the y-axis is the coal seam direction, and the z-axis is the vertical direction..... Pls label on Figure 4 also
The data of the coal rock parameters are calculated (how ?) using the Moore-Coulomb model (Pls write brief methodology how you determine Table 1 contents?)
11303 return air roadway is used as the engineering background, combined with geological conditions (Can you specify some ? like ?) , according to the original plan to excavate along the floor of the coal seam
How Figures 6, 7 was obtained ? Through which software? What was the model limit conditions?
The problem statement, research gap is also missing in introduction part?
The objectives are not clear? Kindly rewrite?
There are no Materials and Methods & Results and Discussions Sections as per MDPI format? Pls include
roadway structural morphology can you elaborate how you have determined it in methodology and than discuss it results?
the mechanical properties of weakly cemented soft rock can you elaborate how you have determined it in methodology and than discuss it results?
The failure of the roadway surrounding rock is mainly shear failure and tensile failure - How you determined it? Pls elaborate
Shear failure mainly occurs in the top and bottom corners of the roadway and the two sides of the roadway, and tensile failure mainly occurs in the roof and floor of the road ----- Pls quantify?
with the increase of the aspect ratio of the roadway, the plastic failure zone increases, especially the top and bottom corners ----- No experimental support pls elaborate how and quantify it?
When the roadway aspect ratio is small, it is conducive to the stability of the roadway surrounding rock. In actual production, under the premise of meeting the roadway width, the roadway height can be increased appropriately to improve the stability of the surrounding rock ----- No experimental support pls elaborate how and quantify it?
Table 2. Why aspect ratio of 0.88 to 1.38 ? is it hypothetical pls explain? The height of roadway needs to be discussed in term of layers thickness presently it seems ill logical. Pls compare with 1-24 reference any other also use if same aspect ratio? what was their findings?
Table 1 the parameters if you determined than mention in methodology and discuss in results, if taken from 1-24 literature than cite it.
Figure 5 how model was prepared pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Figure 6 how vertical stress profile was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Figure 7 how vertical displacement profile was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Figure 8 how plastic zone distribution was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
FLAC3D is used to establish the numerical model, and the current cross-sectional size of the upper and lower chute roadway is 4.0m×5.5m. ----- why FLAC3D ??? pls list the input and boundary limits of the model with any assumptions used.
Figures 9 & 10 how vertical stress distribution was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Figure 11 how plastic zone distribution was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Pls differentiate between Mohr Coulomb, Moore Columb and z-directional deformation law of surrounding - - - You can use a table with necessary information about its input paramaters, boundary conditions and output achieved ... This can be the part of your discussion.
Conclusions
Authors are requested to bring conclusions in line with objectives?
Pls make conclusions quantifiable like
Changing the way of retaining the top or bottom coal can improve the stability of the surrounding rock (from ---- to ------). When changing from (from ---- to this---) retaining the top coal to retaining the bottom coal, the vertical stress high-stress area is reduced (from ---- to this---) and its stress peak is also decreased (from ---- to this---) ; the vertical displacement influence range ((from ---- to this---) of the roof and floor becomes smaller; the plastic failure range is obviously reduced ((from ---- to this---) , especially the bottom corners.
Likewise above in other conclusions also.
Pls increase the references. Pls include some MDPI journals in references. When you enter keywords of the special issue you will get some.
All the best.
Author Response
Response to Reviewer 3 Comments
Point 1：Sorry as there are no line numbers in manuscript so I pick the sentences. Pls see the highlighted / colored text as queries.
Response 1: I am sorry there are no line numbers, and they were added in a continuous mode.
Point 2：Abstract：If the bottom coal is retained, the stress, deformation and plastic zone of weakly cemented soft rock roadway show a decreasing trend- Pls quantify?
Response 2: The abstract has been refined and revised. In the abstract, the quantitative description of the downward trend of vertical stress, displacement and plastic region under the mode of retaining bottom coal is added.
Point 3：Abstract：if the aspect ratio of the roadway is changed by the equal area method - Pls quantify?
Response 3: The aspect ratio of roadway is reasonably assumed by the principle of equal area, and relevant references are added in our manuscript.
Point 4：Abstract：So the reasonable retaining coal mode and the aspect ratio of the roadway can prevent the deformation and failure of the weakly cemented soft rock roadway - Can you pls quantify?
Response 4: The abstract has been refined and revised. In the abstract, the quantitative description of the downward trend of vertical stress, displacement and plastic region under the mode of retaining bottom coal is added.
Point 5：Pls revisit and try to incorporate few keywords of this special issue in title, abstract and text i.e.
- deep mining
- soft rock support
- surrounding rock control
- support technology and equipment
- design and evaluation of support system
Keywords: Structural morphology of roadway; weakly cemented soft rock. Pls revisit?
Response 5: In the keyword section of the manuscript, some keywords requsted by the special issue are added.
Point 6：Introduction: The weakly cemented soft rocks of the Triassic, Cretaceous, and Jurassic are widely distributed in the western regions of Xinjiang, Gansu, Ningxia, and Western Inner Mongolia in China - Can you pls add a Map as Figure showing the distribution zoning?
Response 6: The distribution of weakly cemented soft rock in western China is illustrated by quoting other papers. Scholars have conducted extensive research on weak cemented soft rock in western China.
Point 7：From the perspective of disaster management,- Pls enter the reference.
Response 7: Relevant references on disaster management are supplemented in our manuscript.
Point 8: Therefore, the reasonable layout of roadway shape is explored from the root of stress, so as to prevent and control the deformation and failure of weakly cemented soft rock roadway - How Authors can give such statement in Introduction? Can be in your methodology ? Kindly revisit?
Response 8: Through inspection and review, it was found that the statement was not accurate enough. We have revised this statement in our manuscript.
Point 9：Can you pls enter some notable Figures or tables from references mentioned from 1 to 25 especially from some domestic scholars? This will uplift the background portion a lot?
Response 9: The Introduction has been rearranged and revised. The rich achievements of researchers can serve as the research background and theoretical support of our manuscript.
Point 10：From the perspectives of theoretical research, laboratory experiment, similar simulation, numerical calculation and industrial experiment, scholars have carried out corresponding research on the damage and failure of weakly cemented soft rock and the deformation control technology of surrounding rock, and obtained fruitful research results from the control technology of weakly cemented soft rock roadway - Can you share some? This will be the grounds of your problem statement.
Response10: The Introduction has been rearranged and revised. The revised description is combined with the existing problems of weakly cemented soft rock roadway in our manuscript. The control technology of weakly cemented soft rock roadway is introduced in detail in the Introduction Section.
Point 11：Figure 1 please label
Response11: Figure 1 has been modified. A detailed description is added to the figure.
Point 12：Due to the influence of factors such as large buried depth, high ground stress, poor lithology and rich floor water.... Pls add reference .
Response 12: Relevant references have been added to our manuscript.
Point 13：In August 2020, after the temporary suspension of mining at 11303 working face, the bearing capacity of the roadway support was significantly reduced (Can you specify the quantity ?)
Response 13: The roadway bearing capacity decreased significantly, which was directly obtained through on-site observation, and there was no monitoring data. This will be explained in the subsequent discussion section.
Point 14：and the deformation of the roadway was further aggravated (Can you specify the quantity ?)
Response 14: The roadway deformation was further aggravated. It can be seen from Figure 2 that there is obvious floor heave, and the maximum floor heave can reach 1m, which has been mentioned previously.
Point 15：which led to the failure of the support body and the phenomenon of coal wall caving, floor heave and side shrinkage at the working face, which is very likely to induce roof and floor disaster accidents and significantly increase the degree of safety risk. Reference Pls.
Response 15: Relevant references have been added to our manuscript.
Point 16：Through the lithological analysis and mechanical properties, Can you enter a table of these values?
Response 16: This section is an overview of the project. For the problem description, the general description is adopted, without detailed discussion. For lithology and mechanical parameters, the following numerical simulation will reflect.
Point 17：The action of high stress (Can you specify the quantity ?) serious rheological deformation (Can you specify the quantity ?), resulting in the working face back mining roadway deformation increased (Can you specify the quantity ?) sharply, the......
Response 17: High stress action, serious rheological deformation, roadway deformation increase and other phenomena are all found through long-term on-site observation, lacking of monitoring data. This issue will be explained in the discussion section.
Point 18：For the deformation and failure of the roadway, the preliminary analysis found that the floor is sandy sandstone, which is a weak floor, and the floor is the release port of stress or energy under the excavation -- Can you introduce an excavation section labelling different layers ?
Response 18: For the deformation and failure process of the roadway, the stress of the surrounding rock of the roadway will transfer to the surrounding rock after the excavation is unstable, and the failure will start from the position with relatively weak strength. For a roadway support system, the floor support strength is relatively small. In addition, weak cemented soft rock floor is more likely to be damaged.
Point 19: where the x-axis is the coal seam tendency, the y-axis is the coal seam direction, and the z-axis is the vertical direction..... Pls label on Figure 4 also
Response 19: Figure 4 was modified to mark the coal seam's tendency and strike, as well as the model's x axis and y axis and other information.
Point 20: The data of the coal rock parameters are calculated (how ?) using the Moore-Coulomb model (Pls write brief methodology how you determine Table 1 contents?)
Response 20: The mechanical parameters of coal and rock in Table 1 were measured in the laboratory, rather than calculated by the Mohr- Coulomb model, which was not clearly expressed and caused ambiguity, and has been modified in our manuscript.
Point 21: 11303 return air roadway is used as the engineering background, combined with geological conditions (Can you specify some ? like ?) , according to the original plan to excavate along the floor of the coal seam
Response 21: Geological conditions of 11303 working face are added in Section 2.1 our manuscript.
Point 22: How Figures 6, 7 was obtained ? Through which software? What was the model limit conditions?
Response 22: Figure 6 and Figure 7 were obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 6 and Figure 7.
Point 23: The problem statement, research gap is also missing in introduction part?
Response 23: The Introduction has been rearranged and revised. Added the problem statement and research gap in Induction.
Point 24: The objectives are not clear? Kindly rewrite?
Response 24: The research objective of this paper is to discuss the influence of the shape of weak cemented soft rock roadway on its mechanical properties. The introduction part has been rearranged and revised to clearly explain the research goal and research ideas.
Point 25: There are no Materials and Methods & Results and Discussions Sections as per MDPI format? Pls include
Response 25: According to MDPI format, materials, methods, results and other parts are highlighted, and discussion parts are added.
Point 26: roadway structural morphology can you elaborate how you have determined it in methodology and than discuss it results?
Response 26: The structural form of the roadway is properly explored and improved according to the site conditions. For example, the existing coal retaining method is to retain top coal, so the assumption of retaining bottom coal is proposed to compare and analyze the response of the two to the roadway surrounding rock mechanics. For another example, the section of the original roadway is wide × Height=5.5m × On this basis, according to the principle of equal area, a reasonable width to height ratio assumption is put forward, and the influence of the mechanical properties of surrounding rocks of roadways with different width to height ratios is compared and analyzed.
Point 27: the mechanical properties of weakly cemented soft rock can you elaborate how you have determined it in methodology and than discuss it results?
Response 27: In the manuscript, the mechanical properties of weak cemented soft rock are simulated by FLAC3D simulation software for different roadway structural morphology, and the vertical stress changes of roadway surrounding rock are compared and analyzed, as well as the plastic failure area and deformation caused by roadway surrounding rock are studied. So as to determine the influence of mechanical characteristics of weak cemented soft rock roadway on its stability.
Point 28: The failure of the roadway surrounding rock is mainly shear failure and tensile failure - How you determined it? Pls elaborate
Response 28: The plastic failure of roadway is reflected by the plastic state diagram in FLAC3D simulation, which is described in detail in the manuscript.
Point 29: Shear failure mainly occurs in the top and bottom corners of the roadway and the two sides of the roadway, and tensile failure mainly occurs in the roof and floor of the road ----- Pls quantify?
Response 29: The failure type and failure range of the plastic region are directly reflected in Figures 8 and 11.
Point 30: with the increase of the aspect ratio of the roadway, the plastic failure zone increases, especially the top and bottom corners ----- No experimental support pls elaborate how and quantify it?
Response 30: The plastic zone of the roadway is obtained through FLAC3D, as shown in Figure 11. The plastic zone of roadway under different aspect ratios of roadway width to height is obtained by direct comparison in Figure 11.
Point 31: When the roadway aspect ratio is small, it is conducive to the stability of the roadway surrounding rock. In actual production, under the premise of meeting the roadway width, the roadway height can be increased appropriately to improve the stability of the surrounding rock ----- No experimental support pls elaborate how and quantify it?
Response 31: For the influence of roadway aspect ratio on the stability of its surrounding rock, our manuscript makes a comparative analysis from three aspects of vertical stress, displacement and plastic zone, thus obtaining that when the roadway area is equal, the roadway surrounding rock is relatively stable when the width height ratio is small.
Point 32: Table 2. Why aspect ratio of 0.88 to 1.38 ? is it hypothetical pls explain? The height of roadway needs to be discussed in term of layers thickness presently it seems ill logical. Pls compare with 1-24 reference any other also use if same aspect ratio? what was their findings?
Response 32: The width and height of 11303 air return roadway are 5.5m and 4.0m, respectively. Different width height ratios in Table 2 are assumed based on the existing roadway size and the principle of equal area. The relevant references about the influence of roadway aspect ratio on roadway stability are supplemented in the Introduction, and the reference significance of their research results for our manuscript is analyzed.
Point 33: Table 1 the parameters if you determined than mention in methodology and discuss in results, if taken from 1-24 literature than cite it.
Response 33: The Introduction has been reorganized and revised. The influence of roadway structural morphology on roadway stability was clearly introduced in The Introduction.
Point 34: Figure 5 how model was prepared pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Response 34: Figure 5 was obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 5.
Point 35: Figure 6 how vertical stress profile was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Response 35: Figure 6 was obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 6.
Point 36: Figure 7 how vertical displacement profile was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Response 36: Figure 7 was obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 7.
Point 37: Figure 8 how plastic zone distribution was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Response 37: Figure 8 was obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 8.
Point 38: FLAC3D is used to establish the numerical model, and the current cross-sectional size of the upper and lower chute roadway is 4.0m×5.5m. ----- why FLAC3D ??? pls list the input and boundary limits of the model with any assumptions used.
Response 38: FLAC3D can simulate the mechanical characteristics of three-dimensional structures of soil, rock and other materials and analyze the plastic flow. FLAC3D adopts explicit Lagrangian algorithm and hybrid discrete partition technology, which can accurately simulate the plastic failure and flow of materials. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted.
Point 39: Figures 9 & 10 how vertical stress distribution was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Response 39: Figure 9 &10 was obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 9 &10.
Point 40: Figure 11 how plastic zone distribution was modelled pls list the input and boundary limits of the model with any assumptions used. How model was achieved i.e. tools used.
Response 40: Figure 11 was obtained by FLAC3D software. Related information such as model boundary conditions and rock parameters are described in Section 2.3. In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 11.
Point 41: Pls differentiate between Mohr Coulomb, Moore Columb and z-directional deformation law of surrounding - - - You can use a table with necessary information about its input parameters, boundary conditions and output achieved … This can be the part of your discussion.
Response 41: “Moore Columb” is a spelling error. Mohr Coulomb is the correct spelling. Mohr Coulomb criterion is commonly used to describe rock failure.
Point 42: Conclusions: Authors are requested to bring conclusions in line with objectives?
Response 42: According to the research objectives, the conclusions have been refined and revised.
Point 43: Pls make conclusions quantifiable like
Changing the way of retaining the top or bottom coal can improve the stability of the surrounding rock (from ---- to ------). When changing from (from ---- to this---) retaining the top coal to retaining the bottom coal, the vertical stress high-stress area is reduced (from ---- to this---) and its stress peak is also decreased (from ---- to this---) ; the vertical displacement influence range ((from ---- to this---) of the roof and floor becomes smaller; the plastic failure range is obviously reduced ((from ---- to this---) , especially the bottom corners.
Likewise above in other conclusions also.
Response 43: The conclusion has been refined and revised, and quantitative description has been added.
Point 44: Pls increase the references. Pls include some MDPI journals in references. When you enter keywords of the special issue you will get some.
Response 44: References to MDPI have been added to our manuscript.
Author Response File: 
Author Response.docx
Round 2
Reviewer 1 Report
Thanks for the responses from authors, the quality of this paper has been obviously improved after the careful revision. The manuscript could be accepted for the publication if the following questions can be answered:
(1) Line 266-267, could you make some comments for the statement that the stress concentration coefficient is reduced 10 from 1.67 to 1.64, is it a remarkable decrease? Is it reasonable?
(2) I would like to suggest the authors to change the term of ‘this paper’ into ‘this study’ or ‘this work’.
(3) The format of References should be uniform. Please check reference 8 and 11.
(4) In the Literature Review part, how about other research studies? Other literature for the same purpose (or similar) can be added, addressing the assumptions, main challenges, and advancements. Several unquoted publications on this topic are highly recommended: doi.org/10.1016/j.soildyn.2022.107456& doi.org/10.1016/j.enggeo.2016.12.012&doi.org/10.1016/j.engfailanal.2020.104611
(5) In the last paragraph of the Introduction Section, the organization of this study should be clearly stated.
(6) The Abstract seems too long in my view.
Author Response
Response to Reviewer 1 Comments Round 2
Point 1: Line 266-267, could you make some comments for the statement that the stress concentration coefficient is reduced from 1.67 to 1.64, is it a remarkable decrease? Is it reasonable?
Response 1: The description in this part is inaccurate and has been modified.
Point 2: I would like to suggest the authors to change the term of ‘this paper’ into ‘this study’ or ‘this work’.
Response 2: The term has been changed.
Point 3: The format of References should be uniform. Please check reference 8 and 11.
Response 3: The format of References gave been checked and modified.
Point 4: In the Literature Review part, how about other research studies? Other literature for the same purpose (or similar) can be added, addressing the assumptions, main challenges, and advancements. Several unquoted publications on this topic are highly recommended: doi.org/10.1016/j.soildyn.2022.107456& doi.org/10.1016/j.enggeo.2016.12.012&doi.org/10.1016/j.engfailanal.2020.104611
Response 4: The Introduction part has been rearranged to supplement the current main challenges and advancements of weakly cemented soft rock.
Point 5: In the last paragraph of the Introduction Section, the organization of this study should be clearly stated.
Response 5: The last paragraph of Introduction is reorganized and revised.
Point 6: The Abstract seems too long in my view.
Response 6: The Abstract has been reorganized.
Reviewer 2 Report
My comments on the original manuscript have been sufficiently addressed by the authors. I appreciate the effort of the authors in responding and revising the manuscript. I have no further comment on the technical aspect. I think the revised manuscript may be accepted for publication after a final round of proofreading (e.g., the first sentence in the abstract has grammar errors in the highlighted section).
Author Response
Response to Reviewer 2 Comments Round 2
Point 1: My comments on the original manuscript have been sufficiently addressed by the authors. I appreciate the effort of the authors in responding and revising the manuscript. I have no further comment on the technical aspect. I think the revised manuscript may be accepted for publication after a final round of proofreading (e.g., the first sentence in the abstract has grammar errors in the highlighted section).
Response 1: Thank you for your efforts to our manuscript. The manuscript has been carefully proofread.
Reviewer 3 Report
Abstract can be further modified by quantitatively describing
The results show that when retaining top coal is replaced by bottom coal, the high stress zone of vertical 9 stress is reduced (how much?)
The plastic failure range is obviously reduced, especially at the bottom corners (How much?)
Likewise in other portions of abstract?
The plastic failure range is obviously reduced, especially at the bottom corners (Pls avoid repetition)
Abstract need careful re-reading?
Keywords: I think you can add few more pls revisit?
Point 6 Kindly revisit the addition can improve the understanding of readers?
Point 9：Can you pls enter some notable Figures or tables from references mentioned from 1 to 25 especially from some domestic scholars? No relevant figures / tables added. Can you pls add Figures/Tables.
Response 13: The roadway bearing capacity decreased significantly, which was directly obtained through on-site observation, and there was no monitoring data. This will be explained in the subsequent discussion section -, Bearing capacity can not be determined through observation. Kindly revisit your statement.
Point 16：Through the lithological analysis and mechanical properties, Can you enter a table of these values? Kindly reconsider, it will improve understanding.
Response 17: High stress action, serious rheological deformation, roadway deformation increase and other phenomena are all found through long-term on-site observation, lacking of monitoring data. This issue will be explained in the discussion section. I am sorry I could not find it in discussion section.
Point 18：For the deformation and failure of the roadway, the preliminary analysis found that the floor is sandy sandstone, which is a weak floor, and the floor is the release port of stress or energy under the excavation -- Can you introduce an excavation section labelling different layers ? Kindly revist.
Point 24: The objectives are not yet clear? Kindly rewrite? Shape is relative word ? Can you replace with some logical parameter?
Point 31: When the roadway aspect ratio is small, it is conducive to the stability of the roadway surrounding rock. In actual production, under the premise of meeting the roadway width, the roadway height can be increased appropriately to improve the stability of the surrounding rock ----- No experimental support pls elaborate how and quantify it? Response still unclear please write?
Different width height ratios in Table 2 are assumed based on the existing roadway size and the principle of equal area Response 32 Not clear pls re elaborate.
In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 6. Response 35 is unclear Pls revisit.
Point 41: Pls differentiate between Mohr Coulomb, and z-directional deformation law of surrounding - - - You can use a table with necessary information about its input parameters, boundary conditions and output achieved … This can be the part of your discussion. Pls revisit and add a table.
Spelling and vocabulary need serious attention.
Authors are requested to observe the MDPI format of headings.
Authors are requested to kindly revisit the paper in light of all our previous comments and try to incorporate them in paper. That will improve the understanding of readers significantly.
All the best
Author Response
Response to Reviewer 3 Comments Round 2
Point 1: Abstract can be further modified by quantitatively describing.
Response 1: Abstract has been reorganized and revised.
Point 2: The results show that when retaining top coal is replaced by bottom coal, the high stress zone of vertical stress is reduced (how much?)
Response 2: The comparison of plastic failure zone is made by direct comparison of FLAC3D results (Figure 6), and there is still a lack of reliable quantification method.
Point 3: The plastic failure range is obviously reduced, especially at the bottom corners (How much?) Likewise in other portions of abstract?
Response 3: The comparison of plastic failure zone is made by direct comparison of FLAC3D results (Figure 8 and Figure 11), and there is still a lack of reliable quantification method.
Point 4: The plastic failure range is obviously reduced, especially at the bottom corners (Pls avoid repetition)
Response 4: Abstract is reorganized and modified to avoid repetition.
Point 5: Abstract need careful re-reading?
Response 5: Abstract has been re-read and re-revised.
Point 6: Keywords: I think you can add few more pls revisit? Kindly revisit the addition can improve the understanding of readers?
Response 6: The keywords section has been modified and added “coal retention mode; roadway aspect ratio”
Point 7：Can you pls enter some notable Figures or tables from references mentioned from 1 to 25 especially from some domestic scholars? No relevant figures / tables added. Can you pls add Figures/Tables.
Response 7: The Introduction part has been organized and summarized again. The research status introduced the influencing factors of soft rock roadway and the influence of structural morphology on roadway stability. The current research difficulties and hot issues are described in the last paragraph of the Introduction.
Point 8：Response 13: The roadway bearing capacity decreased significantly, which was directly obtained through on-site observation, and there was no monitoring data. This will be explained in the subsequent discussion section -, Bearing capacity can not be determined through observation. Kindly revisit your statement.
Response 8: The roadway bearing capacity decreased significantly, which was obtained through on-site observation and analysis of support stress (Figure 3). There was no specific long-term monitoring data directly indicating the decline of roadway bearing capacity.
Point 9：Through the lithological analysis and mechanical properties, Can you enter a table of these values? Kindly reconsider, it will improve understanding.
Response 9: The simulation in the manuscript is based on the Mohr-Coulomb model. Lithology and mechanical parameters are shown in Figure 4 and Table 1. The study of mechanical properties mainly refers to the vertical stress distribution law, as well as the deformation and plastic failure area embodied in the surrounding rock.
Point 10：Response 17: High stress action, serious rheological deformation, roadway deformation increase and other phenomena are all found through long-term on-site observation, lacking of monitoring data. This issue will be explained in the discussion section. I am sorry I could not find it in discussion section.
Response 10: The phenomenon of high stress, serious rheological deformation, and increased roadway deformation was found in the field observation, and there is a lack of monitoring data at present. This will be a problem that needs to be solved in the future, which is explained in detail in Section 5.3.
Point 11：For the deformation and failure of the roadway, the preliminary analysis found that the floor is sandy sandstone, which is a weak floor, and the floor is the release port of stress or energy under the excavation -- Can you introduce an excavation section labelling different layers ? Kindly revist.
Response 11: The thickness of coal seam 3-1 is 5m and its floor is mudstone. When the method of retaining coal is discussed in Section 3, the mining thickness is 4m and the retaining thickness is 1m. The floor in different method can be seen in Figure 5. In Section 4, the roadway aspect ratio is discussed based on the method of bottom coal, and coal of corresponding thickness will be set aside for different roadway heights.
Point 12: The objectives are not yet clear? Kindly rewrite? Shape is relative word ? Can you replace with some logical parameter?
Response 12: The structural morphology of the roadway studied in this manuscript not only refers to the shape, but also includes the roof and floor structure of the roadway. The discussion of retaining the top or bottom coal in the manuscript is the discussion of the roof and floor structure.
Point 13: When the roadway aspect ratio is small, it is conducive to the stability of the roadway surrounding rock. In actual production, under the premise of meeting the roadway width, the roadway height can be increased appropriately to improve the stability of the surrounding rock ----- No experimental support pls elaborate how and quantify it? Response still unclear please write?
Response 13: “In actual production, on the premise of meeting the roadway width, the roadway height can be appropriately increased to improve the stability of surrounding rock " is only a reasonable inference, but not supported by experimental data, which needs to be verified by experimental data. The phrase was deleted from the manuscript.
Point 14: Different width height ratios in Table 2 are assumed based on the existing roadway size and the principle of equal area Response 32 Not clear pls re elaborate.
Response 14: The aspect ratio of roadway in Table 2 is a reasonable assumption based on the cross-section of existing roadway based on the principle of equal area. The thickness of the 3-1 coal seam is 5m, and the assumed height of the roadway is 4.0m~5.0m, so there is no stratified mining.
Point 15: In order to reflect the situation of the11303 return air roadway, only part of the model was intercepted in Figure 6. Response 35 is unclear Pls revisit.
Response 15: Figure 6 was obtained by FLAC3D software. Section 2.3 describes the model boundary conditions, rock parameters and other relevant information. In order to reflect the situation of the 1303 return roadway, only part of the model is selected in Figure 6, and the selected part can reflect the changes of the surrounding rock of the roadway.
Point 16: Pls differentiate between Mohr Coulomb, and z-directional deformation law of surrounding - - - You can use a table with necessary information about its input parameters, boundary conditions and output achieved … This can be the part of your discussion. Pls revisit and add a table.
Response 16: Mohr-Coulomb model is the mechanical constitutive model used in this simulation. The z-direction deformation law is the vertical displacement law. In order to avoid ambiguity, it is modified in the manuscript. Mohr-Coulomb model is a constitutive model commonly used in geotechnical engineering. Its model parameters and boundary conditions are conventional parameters, which are described in detail in Section 2.3.
Point 17: Spelling and vocabulary need serious attention.
Response 17: The whole manuscript was carefully checked.
Point 18: Authors are requested to observe the MDPI format of headings.
Response 18: The full manuscript has been revised as requested.
Point 19: Authors are requested to kindly revisit the paper in light of all our previous comments and try to incorporate them in paper. That will improve the understanding of readers significantly.
Response 19: Thank you reviewers for your efforts for the quality of our manuscript. We fully absorb suggestions and incorporate them into the manuscript.
Round 3
Reviewer 1 Report
The author has not carefully and deeply revised the paper according to the review recommendations, and the current paper quality cannot meet the publication requirements of this journal. The manuscript may be accepted for the publication if the following questions can be answered:
(1) Line 6-7 of the Abstract, could you make some comments for the statement that the stress concentration coefficient is reduced 10 from 1.67 to 1.64, is it a remarkable decrease? Is it reasonable?
(2) The quality of Figure 1, 4 and 11 must be improved to meet the standard of this journal.
(3) In the Literature Review Section, other literature for the similar purpose shoud be added, addressing the assumptions, main challenges, and advancements. Several unquoted publications on this topic should be added in the list: doi.org/10.1016/j.soildyn.2022.107456& doi.org/10.1016/j.enggeo.2016.12.012&doi.org/10.1016/j.engfailanal.2020.104611
(4) The writing is recommended to be improved. I found some grammatical errors. Please polish the writing and English of the manuscript.
(5) Line 266-267, could you make some comments for the statement that the stress concentration coefficient is reduced 10 from 1.67 to 1.64, is it a remarkable decrease? Is it reasonable?
(6) Conclusion section must go deeper. Please improve the conclusion section. Also, limitations in the developed approach should be discussed in the conclusions section.
Author Response
Response to Reviewer 1 Comments Round 3
Point 1: Line 6-7 of the Abstract, could you make some comments for the statement that the stress concentration coefficient is reduced 10 from 1.67 to 1.64, is it a remarkable decrease? Is it reasonable?
Response 1: The stress concentration coefficient is reduced from 1.67 to 1.64. It is a slight decrease. This question has been modified in our manuscript.
Point 2: The quality of Figure 1, 4 and 11 must be improved to meet the standard of this journal.
Response 2: According to the standard of the journal, Figures 1, 4 and 11 have been modified.
Point 3: In the Literature Review Section, other literature for the similar purpose should be added, addressing the assumptions, main challenges, and advancements. Several unquoted publications on this topic should be added in the list: doi.org/10.1016/j.soildyn.2022.107456& doi.org/10.1016/j.enggeo.2016.12.012&doi.org/10.1016/j.engfailanal.2020.104611
Response 3: In the literature review section, similar kinds of literature have been added.
Point 4: The writing is recommended to be improved. I found some grammatical errors. Please polish the writing and English of the manuscript.
Response 4: In view of the grammar problems of the manuscript made a comprehensive revision, and the full text has been polished.
Point 5: Line 266-267, could you make some comments for the statement that the stress concentration coefficient is reduced 10 from 1.67 to 1.64, is it a remarkable decrease? Is it reasonable?
Response 5: The stress concentration coefficient is reduced from 1.67 to 1.64. It is a slight decrease. This question has been modified in our manuscript.
Point 6: Conclusion section must go deeper. Please improve the conclusion section. Also, limitations in the developed approach should be discussed in the conclusions section.
Response 6: Combined with the research content, the Conclusions have been modified. In addition, the limitations of the developed approach have been discussed in the conclusions section.
Reviewer 3 Report
Hi Authors
Thanks for incorporating comments in Authors reply document. However, the revised paper did not incorporate the changes. May be wrong file was annexed.
A lot of grammatical mistakes. Need a thorough inspection from a native English speaker or software like Grammarly.
Citation style is incorrect/inconsistent all over the manuscript. Please refer to authors guidelines and published papers for correct way to cite papers at the start, at the end and in between the sentences.
In leu of the previous comments, the conclusions are just stating the results and not the contribution of the manuscript. The conclusions should be revised extensively.
Thanks
Comments for author File: Comments.pdf
Author Response
Response to Reviewer 3 Comments Round 3
Point 1: A lot of grammatical mistakes. Need a thorough inspection from a native English speaker or software like Grammarly.
Response 1: In view of the grammar problems of the manuscript made a comprehensive revision, and the full text has been polished.
Point 2: Citation style is incorrect/inconsistent all over the manuscript. Please refer to authors guidelines and published papers for correct way to cite papers at the start, at the end and in between the sentences.
Response 2: The citation of the manuscript has been completely revised with reference to the author's Guide.
Point 3: In leu of the previous comments, the conclusions are just stating the results and not the contribution of the manuscript. The conclusions should be revised extensively.
Response 3: Combined with the research content, the Conclusions have been modified. In addition, the limitations of the developed approach have been discussed in the conclusions section.
