Study on Initial Fracture Characteristics of the Main Roof in Fully Mechanized Caving Mining of Inclined Coalbed
Round 1
Reviewer 1 Report
（1）Check the article. Language is not easy to follow, with many grammar mistakes.
（2）How to abstract the research object of this paper into the expression of theoretical model should be complete and clear.
（3）This paper briefly describes the problems existing in the roof of the working face in Taoyuan Mine. In view of this problem, it is necessary to further analyze the deflection of the roof and other factors.
（4）The majority of references are from Chinese Journal or Chinese thesis. Please add more international literatures.
Author Response
Response to Reviewer 1 Comments
Thank you very much for the positive comments and constructive suggestions. Please find the following detailed responses to your comments and suggestions.
Point 1: Check the article. Language is not easy to follow, with many grammar mistakes.
Response 1: The content of the article has been further examined and grammatical errors have been corrected.
Point 2: How to abstract the research object of this paper into the expression of theoretical model should be complete and clear.
Response 2: According to the thin plate theory, the primary fracture of the main roof is regarded as an elastic thin plate with four edges clamped before the primary fracture of the main roof, and the load acting on the inclined thin plate is regarded as the resultant force of the normal component force and the tangential component force along the layer, and then the primary fracture mechanics model of the main roof is established.
Point 3: This paper briefly describes the problems existing in the roof of the working face in Taoyuan Mine. In view of this problem, it is necessary to further analyze the deflection of the roof and other factors.
Response 3: Under the background of large dip angle coal seam, the excavation of working face is faced with the problems of difficult management of roof and coal wall, slow propulsion speed and serious damage to hydraulic support. In this context, the roof deflection and other factors in the process of working face excavation are analyzed.
Point 4: The majority of references are from Chinese Journal or Chinese thesis. Please add more international literatures.
Response 4: References in papers have been appropriately adjusted and international literature supplemented.
Specific references are listed as follows:
(1) Skrzypkowski K, Korzeniowski W, Duc T N. Choice of powered roof support FAZOS-15/31-POz for Vang Danh hard coal mine[J]. Inżynieria Mineralna, 2019, 21.
(2) Herezy, Łukasz, Janik, Dariusz and Skrzypkowski, Krzysztof. "Powered Roof Support – Rock Strata Interactions on the Example of an Automated Coal Plough System" Studia Geotechnica et Mechanica, vol.40, no.1, 2018, pp.46-55. https://doi.org/10.2478/sgem-2018-0007.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The article contains interesting analytical and numerical solutions relating to changes in stresses in an inclined hard coal seam. The obtained research results are of a practical nature and seem to be helpful for industrial conditions. Below are some comments and suggestions:
1. In the introduction, it should be mentioned that the assessment of the roof stability and therefore the safety in the longwall space can be determined on the basis of the index of load capacity of the roof "g" (doi: 10.29227 / IM-2019-02-71) and on the basis of the increase pressure in the leg of powered roof support (doi: 10.2478 / sgem-2018-0007).
2. In the second chapter, for the statement "According to the elastic thin plate theory ...", reference should be made to the literature. In addition, it should be written whether the considered load comes only from roof rocks.
3. In the subsection 3.1, a longwall complex should be described in several tasks, of which type: longwall shearer, powered roof support and armoured face conveyor.
4. In the subsection 3.2 for Figures 4 and 5, it should be written what software was used to visualize the results of the maximum principal stress.
5. In the fourth chapter, it is necessary to write what failure criterion was taken into account in numerical models and what parameters were adopted for goaf.
6. Fifth chapter is quite short, so I propose to combine it with fourth chapter as subsection 4.4.
Author Response
Response to Reviewer 2 Comments
Thank you very much for the positive comments and constructive suggestions. Please find the following detailed responses to your comments and suggestions.
Point 1: In the introduction, it should be mentioned that the assessment of the roof stability and therefore the safety in the longwall space can be determined on the basis of the index of load capacity of the roof "g" (doi: 10.29227 / IM-2019-02-71) and on the basis of the increase pressure in the leg of powered roof support (doi: 10.2478 / sgem-2018-0007).
Response 1: The assessment of the roof stability and other contents have been added in the introduction. Besides, relevant literature has also been added.
Specific references are listed as follows:
(1) Skrzypkowski K, Korzeniowski W, Duc T N. Choice of powered roof support FAZOS-15/31-POz for Vang Danh hard coal mine[J]. Inżynieria Mineralna, 2019, 21.
(2) Herezy, Łukasz, Janik, Dariusz and Skrzypkowski, Krzysztof. "Powered Roof Support – Rock Strata Interactions on the Example of an Automated Coal Plough System" Studia Geotechnica et Mechanica, vol.40, no.1, 2018, pp.46-55. https://doi.org/10.2478/sgem-2018-0007.
Point 2: In the second chapter, for the statement "According to the elastic thin plate theory ...", reference should be made to the literature. In addition, it should be written whether the considered load comes only from roof rocks.
Response 2: Relevant references have been added and cited for the elastic thin plate theory in the second chapter. The load considered in the model comes from the overlying strata.
Specific references are listed as follows:
(1) Guojun Wu, Weizhong Chen, Shanpo Jia, Xianjun Tan, Pengqiang Zheng, Hongming Tian, Chi Rong, Deformation characteristics of a roadway in steeply inclined formations and its improved support, International Journal of Rock Mechanics and Mining Sciences, Volume 130, 2020, 104324, ISSN 1365-1609.
Point 3: In the subsection 3.1, a longwall complex should be described in several tasks, of which type: longwall shearer, powered roof support and armoured face conveyor.
Response 3: The Ⅱ1042 working face of Taoyuan Mine adopts single-strike longwall comprehensive mechanized coal mining method, and uses hydraulic support to timely support the exposed roof to reduce the occurrence of roof fall accidents.
Point 4: In the subsection 3.2 for Figures 4 and 5, it should be written what software was used to visualize the results of the maximum principal stress.
Response 4: In the subsection 3.2 for Figures 4 and 5, the contour map of the maximum principal stress was processed and drawn by Matlab.
Point 5: In the fourth chapter, it is necessary to write what failure criterion was taken into account in numerical models and what parameters were adopted for goaf.
Response 5: The damage of material adopts Mohr-Coulomb criterion, and mined-out area is processed by null model which does not need any parameters.
Point 6: Fifth chapter is quite short, so I propose to combine it with fourth chapter as subsection 4.4.
Response 6: I am very able to understand the opinions of experts. The fourth chapter is to analyze the stress change of the main roof first fracture working face in the process of large dip angle coal seam mining by numerical simulation. The fifth chapter is to verify and supplement the previous analysis through field measurement. I think this also has a little logic. However, if the experts still think it is not appropriate, I can make further adjustments. Very sincere.
Author Response File: Author Response.docx
