Simulation Study on Crack Initiation and Energy Mechanisms of Rock-like Samples with Non-Parallel Overlapping Flaws under Uniaxial Compression
Round 1
Reviewer 1 Report
The study is interesting but need to be supplied with detailed numerical model description. Equations, boundary conditions, all closure relationships, e.g., for the forces in Eqns (1-2) have to be added.
Reader should have an ability to reproduce the results of this paper, which is difficult to do without complete description of the mathematical and numerical model.
Author Response
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Reviewer 2 Report
Dear Authors,
The rock cracking is of great practical importance currently. My review questions are:
1) (Line 156) How did you determine the equilibrium state for the sample model? Is the numerical method similar to the finite element method?
2) (Figure 2) The sample model is symmetric with respect to the horizontal line passing through the center. Then it will be sufficient to simulate only the upper half. For the sample model, is it not proper to do that?
3) (Table 1) Most rocks may be anisotropic. How was it considered in simulation or not considered?
4) The pairs of symmetric non-parallel flaws may be rare in real structures. Are such pairs seen frequently in real structures?
5) (Figure 4) The elastic modulus is a material property. Does the elastic modulus in Figure 4 mean the stiffness of the sample model?
6) (Figure 5) The two kinds of results are in agreement, but not in good agreement. The numerical results are higher at small angles and higher at large angles. What can be the cause of such discrepancies?
7) In the phrase “the shape ... changes from flat to full”, “full” may not be the right word.
8) (Figure 14) What does the word “lateral” mean? Does it mean “out of plane” or warping?
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
In this manuscript, PFC2D was used to simulate the non-parallel overlapping double flaws rock-like samples with different inclination angles. These works are expanded on the basis of previous studies. It has some research significance. This paper is acceptable after a minor revision. The authors should address all the following comments and send back the response to each comment.
Question 1: The author's PFC simulation is based on Afolagboye's test, but the material used in Afolagboye's is gypsum, a man-made material, not real rock, so is the simulation generalizable to all natural rock materials?
Question 2: In Section 2.2, the authors obtained macroscopic mechanical parameters consistent with Afolagboye's experiments, but not the actual parameters, by repeatedly debugging them with the "trial and error method". Please explain the reliability of this parameters.
Question 3: The angles selected by the authors for the comparison test in Section 2.2 were 15°, 30°, 45°, and 60°, but in the subsequent study they were 15°, 30°, 45°, 60°, and 75°. Please explain the rationale for the extra 75°.
Question 4: Why did the authors not consider the distance between the two gaps and the length of the two gaps in the modeling of double flaws in rocks?
Question 5: In the double flaws model of rocks established, the fractures are all coplanar, but in the real environment, the case is only an extreme example with great limitations, so why not consider the fractures of non-coplanar fractures?
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Thank you for the improvements.
Reviewer 2 Report
Dear Authors,
Thank you for answering to all questions well.
