Experimental Study on the Size of Rock Fragments Ejected from Boreholes Drilled in Coal Mine Roadway Floors
Round 1
Reviewer 1 Report
The authors investigated the behavior of rock fragments ejected from boreholes drilled in the coal mine roadway. Laboratory experiments were conducted to analyze the size of fragments from three common rocks that might be available during drilling boreholes in a roadway floor. There are some comments to enhance the quality of the paper:
1- Line 119: A minor inconsistency in the format of the font. The phrase “EF-S 1:3.5–5.6 IS STM” is written in a larger font.
2- Line 192, it might be good to add references for equations (like equations 5 and 6). So, the reader can follow how to obtain equations and have a better understanding of the subject.
3- Section 2.2.2. Rock fragment sizes, How does the hardness of the rocks affect the fragment behavior? What if adding the hardness data of the rocks in table 1 and providing a related discussion?
4- Line 377, it is useful to add more information (brief explanation) about the method used to extract crack lines from SEM images via MATLAB.
Author Response
Response to Reviewer 1 Comments
Point 1: Line 119: A minor inconsistency in the format of the font. The phrase “EF-S 1:3.5–5.6 IS STM” is written in a larger font.
Response 1: We have modified it to the correct font.
Point 2: Line 192, it might be good to add references for equations (like equations 5 and 6). So, the reader can follow how to obtain equations and have a better understanding of the subject.
Response 2: A reference has been added.
Point 3: Section 2.2.2. Rock fragment sizes, How does the hardness of the rocks affect the fragment behavior? What if adding the hardness data of the rocks in table 1 and providing a related discussion?
Response 3: As you have mentioned, the rock hardness does affect the fragment size. In our paper, we have discussed it, as shown in line 286~310. It can be seen that the mean size of fragments larger than 1.5 mm increases as the rock UCS increases.
Point 4: Line 377, it is useful to add more information (brief explanation) about the method used to extract crack lines from SEM images via MATLAB.
Response 4: Line 377-381 have explained the method of extracting crack lines. The purpose of identifying the crack can be achieved by adjusting the gray value of the image through MATLAB. And we have added more information in line 380.
Author Response File: 
Author Response.docx
Reviewer 2 Report
In this paper laboratory experiments were used to analyse the size of fragment from three sedimentary rock types (limestone, gritstone, and mudstone) during drilling boreholes in a roadway floor. The sizes of rock fragments have an important influence on fragment discharge. The data presented in the article are very interesting from a scientific point of view and the results could be of importance for the practical application.
Below are some minor changes for improving the quality of the article.
Line 119. Please change font for EF-S 1:3.5–5.6 IS STM
Please change the font for F, s m and other letters, they seem to me as to big comparing to other letters.
Figure 15 – Limestone is not visible, please correct.
Please check the English once again.
Author Response
Response to Reviewer 2 Comments
Point 1: Line 119. Please change font for EF-S 1:3.5–5.6 IS STM
Please change the font for F, s m and other letters, they seem to me as to big comparing to other letters.
Response 1: We have modified it to the correct font.
Point 2: Figure 15 – Limestone is not visible, please correct.
Response 2: The figure has been corrected.
Point 3: Please check the English once again.
Response 3: We have checked the English once again. And we have used a professional English editing service before submitting our manuscript initially.
Author Response File: Author Response.docx
