PONE-D-25-26204Evolutionary Features of Microscopic Damage in Shale Under Unloading ActionPLOS ONE

Dear Dr. She,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jul 26 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Kang Wang, Ph.D.

Academic Editor

PLOS ONE

Journal requirements:

When submitting your revision, we need you to address these additional requirements.

1.  Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf   and

https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. Please note that PLOS ONE has specific guidelines on code sharing for submissions in which author-generated code underpins the findings in the manuscript. In these cases, we expect all author-generated code to be made available without restrictions upon publication of the work. Please review our guidelines at https://journals.plos.org/plosone/s/materials-and-software-sharing#loc-sharing-code and ensure that your code is shared in a way that follows best practice and facilitates reproducibility and reuse.

3. In your Methods section, please provide additional information regarding the permits you obtained for the work. Please ensure you have included the full name of the authority that approved the field site access and, if no permits were required, a brief statement explaining why.

4. We note that this submission includes NMR spectroscopy data. We would recommend that you include the following information in your methods section or as Supporting Information files:

a) The make/source of the NMR instrument used in your study, as well as the magnetic field strength. For each individual experiment, please also list: the nucleus being measured; the sample concentration; the solvent in which the sample is dissolved and if solvent signal suppression was used; the reference standard and the temperature.

b) A list of the chemical shifts for all compounds characterised by NMR spectroscopy, specifying, where relevant: the chemical shift (δ), the multiplicity and the coupling constants (in Hz), for the appropriate nuclei used for assignment.

c)The full integrated NMR spectrum, clearly labelled with the compound name and chemical structure.

We also strongly encourage authors to provide primary NMR data files, in particular for new compounds which have not been characterised in the existing literature. Authors should provide the acquisition data, FID files and processing parameters for each experiment, clearly labelled with the compound name and identifier, as well as a structure file for each provided dataset. See our list of recommended repositories here: https://journals.plos.org/plosone/s/recommended-repositories

4. Thank you for stating the following financial disclosure:

“the Natural Science Foundation of Hubei Province (2024AFB878), the Key Laboratory of Reservoir and Dam Safety of the Ministry of Water Resources is open to research funds (YK323003) and Hubei Provincial Key Laboratory of Oil and Gas Drilling and Production Engineering Open Fund (YQZC202204)”

Please state what role the funders took in the study.  If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

If this statement is not correct you must amend it as needed.

Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf.

5. Thank you for stating the following in the Acknowledgments Section of your manuscript:

“This work was supported by the Natural Science Foundation of Hubei Province (2024AFB878), the Key Laboratory of Reservoir and Dam Safety of the Ministry of Water Resources is open to research funds (YK323003) and Hubei Provincial Key Laboratory of Oil and Gas Drilling and Production Engineering Open Fund (YQZC202204), which are gratefully acknowledged.”

We note that you have provided funding information that is currently declared in your Funding Statement. However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form.

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows:

“the Natural Science Foundation of Hubei Province (2024AFB878), the Key Laboratory of Reservoir and Dam Safety of the Ministry of Water Resources is open to research funds (YK323003) and Hubei Provincial Key Laboratory of Oil and Gas Drilling and Production Engineering Open Fund (YQZC202204)”

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

6. We note that your Data Availability Statement is currently as follows: [All relevant data are within the manuscript and its Supporting Information files.]

Please confirm at this time whether or not your submission contains all raw data required to replicate the results of your study. Authors must share the “minimal data set” for their submission. PLOS defines the minimal data set to consist of the data required to replicate all study findings reported in the article, as well as related metadata and methods (https://journals.plos.org/plosone/s/data-availability#loc-minimal-data-set-definition).

For example, authors should submit the following data:

- The values behind the means, standard deviations and other measures reported;

- The values used to build graphs;

- The points extracted from images for analysis.

Authors do not need to submit their entire data set if only a portion of the data was used in the reported study.

If your submission does not contain these data, please either upload them as Supporting Information files or deposit them to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. For a list of recommended repositories, please see https://journals.plos.org/plosone/s/recommended-repositories.

If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially sensitive information, data are owned by a third-party organization, etc.) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent. If data are owned by a third party, please indicate how others may request data access.

7. PLOS requires an ORCID iD for the corresponding author in Editorial Manager on papers submitted after December 6th, 2016. Please ensure that you have an ORCID iD and that it is validated in Editorial Manager. To do this, go to ‘Update my Information’ (in the upper left-hand corner of the main menu), and click on the Fetch/Validate link next to the ORCID field. This will take you to the ORCID site and allow you to create a new iD or authenticate a pre-existing iD in Editorial Manager.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

Reviewer #4: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: No

Reviewer #3: Yes

Reviewer #4: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The manuscript addresses an important topic concerning the microscopic damage evolution in shale under unloading disturbances—a relevant issue in underground engineering applications such as drilling and mining. The experimental setup is well-designed, combining scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and triaxial tests to analyze damage characteristics and develop a statistical damage model. The integration of digital image processing for quantifying pore features and a mechanistic damage model is a commendable and novel approach.

However, the manuscript would benefit significantly from improvements in clarity, structure, and interpretation of results. Below is a detailed review:

1、 The manuscript contains numerous grammatical and syntactical issues that impede readability. Many sentences are fragmented or lack proper subject-verb agreement. Example from the abstract: “Through the design of rock unloading disturbance tests combined with electron microscope scanning…” is a sentence fragment and should be revised for clarity and grammatical correctness.

2、 The abstract should more clearly state the study’s objective, methodology, key findings, and significance. Currently, it is overly technical and lacks flow.

3、 While the introduction explains the significance of the study, it could benefit from more in-depth references to recent research in the past five years. Highlight gaps in the literature this study addresses, such as: compgeo.2024.106095; tafmec.2024.104691; fuel.2023.129584

4、 The methodology section (Section 2) is detailed but would benefit from being structured into subheadings like "Materials," "Test Protocol," and "Data Analysis Procedures."

5、 Figures and tables are well-detailed, but captions should be more informative. For instance, Fig. 8 should mention that different magnifications were used for different unloading amplitudes and why.

6、 The analysis of dmax/dmin and T2 spectrum shifts is insightful but should include statistical validation (e.g., ANOVA or regression) to support observed trends.

7、 Table 5 and Fig. 22 show clear trends in porosity and expansion, but these should be statistically evaluated to establish thresholds or nonlinear effects.

8、 The assumptions underlying the damage model (e.g., uniform initial stress state, isotropy) should be explicitly stated and discussed.

Reviewer #2: There are actually many studies on rock damage caused by unloading. The author conducted microscopic analysis using nuclear magnetic resonance and SEM. The research results have a certain degree of innovation, but there are mainly the following problems:

(1)The author's microscopic analysis was conducted after unloading, and the damage evolution characteristics during the unloading process cannot be obtained.

(2)SEM experiment is a destructive experiment. How does the author compare the effects of different unloading amplitude.

(3) Is the nuclear magnetic resonance experiment conducted using the same sample or different samples during the unloading experiment. If it is the same sample, is there interference between different unloading experiments? If it is different samples, is it still meaningful to compare them with each other.

(4)The author can refer to this paper "Strength weakening and its micromechanism in water–rock interaction, a short review in laboratory tests" on the advantages and disadvantages of micro experimental methods.

Reviewer #3: This manuscript analyzes the evolution laws of the pore types and mechanical properties on the surface and inside the rock sample after unloading disturbance. The evolution of pore cracks on the sample surface was studied through the classification of the dmax/dmin ratio. A damage quantification method was proposed, and a statistical damage ontology model of the unloading disturbed rock mass was constructed. However, after reviewing the paper carefully, there are still some details that need to modify. So, it is recommended that the paper should be modified significantly so as to increase its readability. Here are some suggestions for checking.

1. The variables that appear for the first time in the abstract need to be given complete words to facilitate readers' understanding. For example, "dmax/dmin".

2. The key words need to correspond to the title and abstract of the manuscript. However, the key words of this manuscript do not reflect the core characteristics of the research content.

3. The author proposes the influence of "unloading disturbances of different amplitudes" on the mechanical characteristics of rocks. What significance should be more clearly expounded in the introduction part in practical engineering?

4. The author describes the experimental equipment involved in the research process in Section 2.1 and lists the pictures of the relevant experimental instruments. In fact, listing these pictures is meaningless. The author should draw a flowchart to help readers understand the research ideas of the manuscript.

5. Section 3.1 of the manuscript describes the similarities in the properties of the selected samples. The first paragraph of section 3.2 presents the experimental scheme of the experimental study of rock unloading disturbance. It would be more reasonable to include these contents in the second chapter of the manuscript.

6. In Section 3.2 "(1) Scanning electron microscope image analysis", it is unreasonable for the author to select images with different magnifications as the original data for image digital processing. Furthermore, the author should elaborate on the basis that the selected scanning electron microscope images can represent the pore characteristics under different unloading amplitudes.

7. Section 3.3 is overly simplistic in analyzing the results of the triaxial force experiment and requires additional analysis content.

8. In Fig.23, the vertical coordinate shows “σ1-σ2”. Is it a true triaxial experiment or a miswrite?

Reviewer #4: This paper explores the micro-damage evolution characteristics and mechanical property changes of shale under unloading through experiments and theoretical analysis, and establishes a damage constitutive model. The research content is rich and has certain engineering value, but there are still some deficiencies in the writing. Therefore, I suggest a major revision. The following are the revision suggestions:

1. The author's statement that "research on rock unloading damage is relatively scarce" is questionable. Researchers have achieved abundant results in this field. Therefore, I suggest that the author reorganize the literature.

2. The introduction and result analysis and discussion are not in-depth enough, lacking in-depth analysis based on fracture mechanics. The following literature is provided for the author's reference:

Analytical solution of the stress field and plastic zone at the tip of a closed crack. Frontiers in Earth Science. 2024.

3. In lines 168-172, why are different magnifications set? Please provide additional explanations in the text. Moreover, inconsistent magnifications of the images may lead to inconsistent results in pore statistics. It is suggested to unify the magnification or explain the comparability of the data under different magnifications.

4. In line 231, the gray-scale threshold is set to 50 (Formula 4), but the basis for selecting this threshold is not explained. It is suggested to verify the rationality of the threshold through sensitivity analysis or to supplement relevant references to validate its rationality.

5. Figure 25 needs to be redrawn to ensure the clarity of the image and the uniformity of the font format.

6. It is suggested to add a chapter on "Research Limitations and Prospects", to further explain the limitations of the model (whether it is applicable to other rocks) and the limitations of the experiments (the selection of unloading rate and amplitude).

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes:  Qiangui Zhang

Reviewer #4: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

Evolutionary Features of Microscopic Damage in Shale Under Unloading Action

PONE-D-25-26204R1

Dear Dr. She,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager®  and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org.

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Kang Wang, Ph.D.

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: (No Response)

Reviewer #2: All comments have been addressed

Reviewer #3: All comments have been addressed

Reviewer #4: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: (No Response)

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: (No Response)

Reviewer #2: The author has made detailed revisions based on the suggestions and comments, and I believe this paper can be publish ed

Reviewer #3: All the comments have been addressed in the new manuscript, and all the questions have been well answered. I suggest that it should be published.

Reviewer #4: The author has carefully revised the paper based on the opinions of the reviewers. I think the paper can already be accepted

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

Reviewer #4: No

**********