Influence of Mesoscopic Parameters of Weakly Cemented Rocks on Macroscopic Mechanical Properties

Round 1

Reviewer 1 Report

In this paper, the influence of micro parameters of weakly cemented rock on macro parameters is studied. Based on the particle flow theory, a weakly cemented rock model is constructed by using PFC and numerical simulation experiments are carried out. The influence of rock meso parameters on macro mechanical properties is analyzed by using the control variable method. The influence of micro parameters on macro mechanics is analyzed by quantitative analysis. The micro parameters which affecting the peak strength, peak strain and elastic modulus are graded. The research scheme is innovative. And the results have reference significance for parameter selection in rock simulation. However, the paper also has the following shortcomings:

1. In the introduction, the description of the contribution part is not enough to highlight the work content of the article. It’s suggested to supplement and improve.

2. The sensitivity parameter analysis is not accurate enough. It needs to be described in numerical value. For example, "the insensitive parameters (Grade III) are the effective modulus of parallel bonding, the friction coefficient of parallel bonding, the stiffness ratio of particles and the effective modulus of particles. The insensitive parameters (Grade III) are particle stiffness ratio and friction coefficient, which make the strain basically stable.

3. The statement is not accurate enough. From Figure 3, not all rock peak strains are less than 0.6%. It is recommended to express the language more accurately.

4. It is suggested to supplement some authors' literature from other countries, not limited to China.

5. The syntax of some statements needs further polishing and modification.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper, the influence of mesoscopic parameters of weakly cemented rock on macroscopic mechanical properties is taken as the research background. The physical properties and mesoscopic parameters of weakly cemented rock are obtained by analyzing the microstructure of rock, uniaxial compression test and acoustic emission test. On this basis, the sample model was constructed by PFC software, and the uniaxial compression numerical simulation experiment and analysis were carried out to clarify the response mechanism between macro and micro parameters. The influence of mesoscopic parameters on the corresponding peak strength, peak strain and elastic modulus is divided into three grades from high to low, and the relationship between macro and mesoscopic parameters in different intervals is further analyzed. The research results of this paper are helpful to carry out more accurate numerical modeling of weakly cemented rocks, and to study the damage and fracture laws of weakly cemented rocks. It is of great significance to find out the differences in the deformation laws of weakly cemented rocks. However, the paper also has the following shortcomings, it is recommended to modify:

1. The introduction of the article does not explain the shortcomings and trends of the existing research in the summary of previous studies;

2. The summary of the article is not full enough, "For simulations of weakly cemented rock, the values of these two are assumed to be relatively small." It is recommended to give a clear numerical range and judgment basis;

3. The analysis of the experimental results in the article lacks numerical language descriptions, such as "the insensitive parameters (grade III) are the parallel bond effective modulus, parallel bond friction coefficient, particle stiffness ratio, and particles effective modulus; changes to these parameters do not cause significant changes in the peak strength." etc.;

4. There are conflicting expressions in the article on the analysis of the friction angle, such as "Meanwhile, as the friction angle is increased from 0 to 15°, the strain increases and changes, after which as the angle is increased from 15 to 80°, the strain decreases monotonically."，"The results for friction angles greater than 60° no longer have any research significance, and thus are not analyzed here. ";

5. Some important literature deserves to be supplemented for supporting the relevant content of this paper, please consider 10.1007/s00603-021-02690-x especially in relation to recent advances in rock mechanics.

6. The article has the problem of misuse of words and grammatical errors in some places. The author is requested to carefully revise and polish the wording of the article. such as "Weakly cemented rocks have discontinuous defects within them, such as particle interfaces, cementing materials, microcracks……", "It can be used to monitor the positions and numbers of microcracks……". etc.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

This paper investigated the mesoscopic parameters of weakly cemented rocks with their mechanical properties by correlating the experimental results regarding the mechanical properties with theoretical simulations obtained by the PFC model. 

I have some remarks and suggestions that may improve the paper's clarity. 

1. The novelty of this paper is not assessed in the existing literature. What this paper brings new? Why the behaviour of such weak rocks should be known?

2. The entire research is a mixture of experimental, theoretical, and given data supposed to be obtained by exploratory testing. On page 6, at line 193, a reference should be cited or some procedures and equipment for friction coefficient establishment should be provided.  Also, a flowchart of the entire research is requested, emphasizing the data obtained by experiment, those found in literature, and those obtained by model simulation. 

3. A validation of the obtained results by comparison with the existing literature would be welcome. 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors answered all the questions and considered all recommendations. In its current form, the article can be recommended for publication.