A Dual DIC System for Analysis of Dynamic Mechanical Properties of Large Sandstone under Uniaxial Compression Load

Round 1

Reviewer 1 Report

1. The article said: "In order to better simulate the cavern environment, 3MPa confining pressure was applied on the left and right sides of the specimen." Please briefly describe the reason for this and explain why the stress state of the experimental design is such a biaxial stress state.

2. In the first section, " At present, there is a strong subjectivity in the selection and ratio of materials for tunnel test. Most of the experimental materials of scholars are small-size real rock mass or large-size similar materials, and few tunnel model tests with large-size real rock mass are conducted. " is suggested to be changed as follows: "At present, in the selection of tunnel test material size, most scholars choose to use small-size simulation material, and further research is needed on the tunnel simulation test of large-size real rock mass."

3. The failure mode of the specimen in this paper is similar to the two-dimensional plane strain problem, while the real cavity is three-dimensional problem. Please briefly describe the difference between the two in the experimental design section.

4. In the second section, the paper spends a lot of space to make a detailed introduction to speckle quality assessment, and it is suggested to add description in the Abstract.

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

This paper performed an experiment to acquire the dynamic mechanical properties of a simulated sandstone tunnel by a dual DIC system. The reviewer thinks the most critical problem in this paper is how the authors ensure the load is applied by uniaxial compression load (without eccentricity). Because it is challenging to be achieved, and even a little eccentricity causes the axial load capacity to change a lot. The reviewer agrees that this paper provides valuable experimental results, which contribute to specifying the rock failure under the dynamic evolution process of crack initiation, expansion, and interpenetration under the action of load. However, some grammar errors and edit problems (in Tables and Figures) need to be revised carefully before this manuscript can be accepted. The reviewer recommends that the authors can clarify the following issues:

1. Page 2, line 72, please use superscript for cubic meter m^3.
2. Page 3, line 93, please explain what A/D conversion is.
3. Page 7, line 183, how the authors ensure the experimental equipment and two cameras are worked simultaneously (with the same working frequency). Which data acquisition system did the authors use in this experiment? Are all equipment and cameras connected to the same data acquisition system?
4. Page 7, please show the location and how many strain gauges were used in this experiment. It is essential to show it because the strain measured in different locations of specimens should have different values. And please explain where the axial strain in Figure 6 came from.
5. Page 7, line 203, how the authors determine the peak load (110kN). Does this value come from a previous experiment, or was it calculated by equations? Because usually, the experimental results have a little different from the experiments.
6. Page 7, Figure 5, the most important thing in this paper is how the authors ensure the load is applied by uniaxial compression load (without eccentricity). Because it is very difficult to be achieved, and even a little eccentricity will be caused the axial load capacity to change a lot.
7. Page 7, Figure 6, can the authors explain why the compaction area appears?
8. Page 9, Figure 7, what is the unit of displacement in this figure? The same problem exists in Figure 9.
9. Page 10, Figure 8, what is the order of magnitude of strain in this figure? The negative third/sixth power of ten? The same problem exists in Figures 10 and 11. Please specify.

Finally, the reviewer will give five suggestions for the authors. (1) Please ensure that all the font types and sizes in one Figure are unified. (2) Please check the grammar errors and typos in this manuscript. (3) The resolution is also essential in improving the paper acceptance rate for a high-quality paper. When adding notation (words, numbers) to an original paper, it is better to be edited in Microsoft software (PowerPoint or Word) and group them. Then, insert it into Microsoft Word. In this way, the resolution of the notation shown on each Figure will have the same resolution as the words in this paper.

Author Response

Please see the attachment！

Author Response File: Author Response.docx