Experimental and Numerical Study of Water–Rock Coupling Creep under Uniaxial Compression

Round 1

Reviewer 1 Report

Minor comments:

- Line 17: What "E" represents is not defined until line 200. The first time the symbol appears, it should be indicated that it is the "instantaneous elastic modulus".

- Line 38: The reference "Li et al." is indicated as 2001, but in the Reference section the year 2011 appears.

- Line 66: The reference "Jiang et al." is indicated as 2016, but in the Reference section the year 2013 appears.

- Figure 3: The symbol "w" appears in the equation of the figure, and although it is clear to understand that it refers to "moisture content %", its meaning is not explicitly defined throughout the text.

- Line 250: The format of the tive of creep rate"of "deriva is not the same as that used for other symbols in the article.

- Line 268: some symbols use different formats.

- Equation (7): Part of the equation (right side) is cut off, it does not appear on the page.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The reviewed paper presents an experimental and numerical study of water-rock coupling and creep under uniaxial compression. The authors conducted a series of tests on sandstone samples to investigate the influence of groundwater on the long-term strength of surrounding rock in deep roadways. They found that water content significantly affects rock's short-term and long-term strength and that the viscosity modulus can be used to describe viscoelastic creep deformation. The results of this study have important implications for the design and construction of deep underground structures.

The quality of the paper and the scientific soundness is high. Therefore, I suggest the paper be published as is. I only have a few optional comments for the authors to consider before publication:

·         The reference style does not seem to match the MDPI style. Please address this issue before publication.

·         Overall, this is a very good and comprehensive introduction to the work.

·         Figure 3. Change the line pattern for the fitting curve.

·         Figure 3. What is the difference between uniaxial comp. strength and failure strength? I would be good if the authors explained this throughout the text.

·         Line 138-139. I would use the term fail rather than destroyed. The authors are also encouraged to go through the text one more time to check the clarity of English and make any final edits that might be needed to improve the readability of the manuscript.

·         Table 2. What causes the yield strength and accelerated yield strength to vary so significantly within samples? Please explain.

·         Equation 1. How is the bearing area in the damage state calculated/ Please explain.

·         Figure 9. What is the R^2 value of the fitting shown?

·         Equation 7 is not fully shown in the paper. Please revise.

·         Figure 11 and Figure 12. Really great fitting of the presented model.

 

·         Line 334-336. What can be causing that slight deviation in the initial creep state?

The authors are also encouraged to go through the text one more time to check the clarity of English and make any final edits that might be needed to improve the readability of the manuscript.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Dear Editors, dear Authors,

Journal: Sustainability (ISSN 2071-1050)

Manuscript ID: sustainability-2602882

Type: Article

Title: Experiment and numerical study of water-rock coupling creep under uniaxial compression

Comments: The article is an interesting study on the phenomenon of the influence of the time parameter on rock properties. Particularly valuable are the results of laboratory studies.

In order to investigate the influence of the long-term strength of the surrounding rock of the deep underground under the influence of groundwater on the stability of the surrounding rock. Uniaxial compression and uniaxial creep tests were carried out on sandstone samples at different water saturation states. The water content was found to have a pronounced softening effect on the short-term and long-term strength, with both strengths showing a negative exponential downward dependence. A viscous modulus was proposed to describe viscoelastic creep deformation. Damage variables D corresponding to E have also been proposed, and a viscous component that can describe accelerated creep has been developed to improve the Nishihara model. A comparison of parameter identification and experimental curves shows that the model can well describe the mechanical behaviour of the different stages of creep. The model was developed using the user subroutine functions of ABAQUS. A simulation of a creep experiment in uniaxial compression was carried out. The simulation results were in general agreement with the experimental results.

The article is scientifically and merit-correct.

Editorial errors are indicated below which the reviewer believes should be corrected prior to publication (see *.pdf).

Thank you.

Yours faithfully.

Comments for author File: Comments.pdf

Author Response

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Reviewer 4 Report

Investigators studied the impact of water saturation on the long-term strength of the surrounding rocks in a deep roadway. Sandstone samples were collected and used for uniaxial testing. Numerical modeling was also conducted to investigate creep behavior. The simulated results and laboratory data are inconsistent. Accelerated creep behavior is further established, and improvements are made to the traditional Nishihara model. In the reviewer's opinion, the conclusion is sound. However, there are some minor comments:

1. Line 82, the water influence degree should be rephrased to "the influence of water saturation degree.

2. Please add specified error range numbers on Line 95.

3. Where and what type of instrument, as well as the instrument's sound frequency, were used for sample wave velocity measurements?

4. Line 99, XRD should be updated as X-ray Diffraction (XRD).

5. In this manuscript, the authors used only one type of sandstone sample. Do the authors' findings apply to other types of rock samples, such as sandstones with different lithology or fabric? If more experimental work is conducted, the conclusion will be more comprehensive.

Minor grammar check is needed before publication.

Author Response

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Author Response File: Author Response.docx