Energy Evolution Analysis of Coal Fracture Damage Process Based on Digital Image Processing

Round 1

Reviewer 1 Report

This paper investigate the fracture properties of coal, subject to uniaxial compressive stress, in relation to the inclination angle of calcite veins. The study relies on a numerical model combined with digital imaging of coal fracture under uniaxial stress. Several aspects are studied: (1) compressive strength, (2) Young modulus, (3) acoustic emission and (4) energy evolution.
I only have the following minor comments/requests for clarification:

1. Introduction

*Is CBM coal-bed methane? please specify it.

*I guess that "Giuseppe ferro" should be "Giuseppe Ferro"

*I think that the topic (calcite angle vs. compression strenth) is very interesting scientifically. However, may you please spend more words on its interest from an industrial standpoint?

2.2. Establishment of the numerical model

*please fix the syntax of the first phrase of section 2.2.

3.1. Mechanical properties anisotropy analysis

* how do you justify on a physical standpoint that compressive strength has a minimum at 60°? (instead of, for example, showing a monotonous behavior?)

Author Response

This paper investigate the fracture properties of coal, subject to uniaxial compressive stress, in relation to the inclination angle of calcite veins. The study relies on a numerical model combined with digital imaging of coal fracture under uniaxial stress. Several aspects are studied: (1) compressive strength, (2) Young modulus, (3) acoustic emission and (4) energy evolution.

Thank you for your constructive comments and suggestions on improving this manuscript. We have read and corrected them carefully (See also in the red marked contents in the revised manuscript).

I only have the following minor comments/requests for clarification:

1. Introduction

*Is CBM coal-bed methane? please specify it.

Answer: Thank you for your constructive comments! Yes, CBM is the abbreviation of coalbed methane in the manuscript, and we have made a detailed description in the manuscript.

*I guess that "Giuseppe ferro" should be "Giuseppe Ferro"

Answer: Thank you for your constructive comments! Yes, "Giuseppe ferro" should be written as "Giuseppe ferro", which we have modified in the manuscript.

*I think that the topic (calcite angle vs. compression strenth) is very interesting scientifically. However, may you please spend more words on its interest from an industrial standpoint?

Answer: Thank you for your constructive comments! We have added a description of this part in the Introduction.

2.2. Establishment of the numerical model

*please fix the syntax of the first phrase of section 2.2.

Answer: Thank you for your constructive comments! We have revised the syntax of the first phrase in Section 2.2.

3.1. Mechanical properties anisotropy analysis

* how do you justify on a physical standpoint that compressive strength has a minimum at 60°? (instead of, for example, showing a monotonous behavior?)

Answer: Thank you for your constructive comments! The compressive strength of coal rocks is consistent with the strength theory of single structural plane proposed by Jaeger J C.

Please see the attachment for detailed modifications！

Author Response File: Author Response.docx

Reviewer 2 Report

This is an interesting manuscript, suitable for publication in Applied Sciences, but that still needs improvements before being accepted for publication. I suggest to check and change some parts of the text and provide some additional information. These are my suggestions:

From the text I have not clear if you have obtained data on compressive strength and elastic modulus. Please, provide clearly the origin of data. If you use published data provide the reference. If you performed measurements provide device and conditions of measurements.

The discussion is poor and does not provide useful information. Please, I suggest to provide a section of “results and discussion” and removing the present discussion.

 

Check English and spelling:

If you use an acronym, please provide first the meaning (e.g. CBM, coalbed methane)

Check spelling in references: “Giuseppe Ferro” instead “Giuseppe ferro”.

Author Response

This is an interesting manuscript, suitable for publication in Applied Sciences, but that still needs improvements before being accepted for publication. I suggest to check and change some parts of the text and provide some additional information. These are my suggestions:

Answer: Thank you for your constructive comments and suggestions on improving this manuscript. We have read and corrected them carefully (See also in the red marked contents in the revised manuscript).

From the text I have not clear if you have obtained data on compressive strength and elastic modulus. Please, provide clearly the origin of data. If you use published data provide the reference. If you performed measurements provide device and conditions of measurements.

Answer: Thank you for your constructive comments! The mechanical parameters of coal rock matrix in the test part of the manuscript refer to literature [41], and the mechanical parameters of quartz refer to literature [42]. We have provided references and marked them in the manuscript.

The discussion is poor and does not provide useful information. Please, I suggest to provide a section of “results and discussion” and removing the present discussion.

Answer: Thank you for your constructive comments! We have taken your suggestion, deleted the discussion part from the manuscript and added "Results and discussion".

 

Check English and spelling:

If you use an acronym, please provide first the meaning (e.g. CBM, coalbed methane)

Answer: Thank you for your constructive comments! We have revised the manuscript.

Check spelling in references: “Giuseppe Ferro” instead “Giuseppe ferro”.

Answer: Thank you for your constructive comments! We have revised the manuscript.

Please see the attachment for detailed modifications

Author Response File: Author Response.docx