-->PONE-D-25-32562-->-->Research on the Microscopic Mechanism of Water Immersion and collapsibility in Malan Loess with Different Particle Size-->-->PLOS ONE

Dear Dr. Mu,

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.

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Jianguo Wang, PhD

Academic Editor

PLOS ONE

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Reviewers' comments:

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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

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

Reviewer #1: Yes

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-->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.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.-->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.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

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Reviewer #1: Yes

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-->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 paper "Research on the Microscopic Mechanisms of Water Immersion-Induced Collapsibility in Malan Loess with Different Particle Sizes" addresses a topic of significant relevance to geological hazard research on the Loess Plateau. The experimental design is systematic, the data are robust, and the conclusions possess considerable academic value and practical relevance for engineering applications. While the paper is strong overall, several details require improvement.

Specific Revision Suggestions:

1. Sample Information: The "Materials" section mentions that sandy, silty, and clayey Malan loess samples were collected from Jingbian County, Yan'an City, and Jingyang County. However, the specific geological context of each sampling site is omitted. Elaborating on this background would greatly enhance the readers' understanding of the samples' representativeness.

2. Sampling Standardization: The description of sample preservation—encapsulation in PVC pipes—lacks critical details regarding the storage environment (e.g., controlled temperature and humidity ranges). These parameters are essential for assessing sample integrity and result reliability. Please supplement this information to ensure full traceability and standardization.

3. Experimental Process Details: In the "SEM Test" section, the protocol for sample preparation mentions a curing mixture of epoxy resin, acetone, ethylenediamine, and dibutyl phthalate, but omits the specific proportions of each component. Providing these key parameters is crucial for the reproducibility of the experiment.

4. Chart Clarity: The captions for figures, such as Figure 4 ("Loest Particle Size Distribution") and Figure 5 ("Mineral Test Results of Loess with Different Clay Contents"), should explicitly state the correspondence between sample numbers and their respective sampling locations. This addition is necessary to allow readers to easily identify the source of each data presentation.

5. Conclusion Specificity: The fourth point of the conclusion section, which proposes a "micro-collapse mechanism model," is currently too vague. To strengthen the impact and practicality of this finding, please elaborate on the model's core elements (e.g., particle contact modes, pore evolution laws) and its specific applications in fields such as loess region engineering geology and disaster prevention.

Overall Evaluation:

This paper tackles an important subject with academic and practical merit. Its methodology is sound, and its core conclusions are well-supported. The issues identified pertain primarily to the elaboration of details, data presentation, and mechanistic discussion, all of which can be addressed with straightforward revisions. It is recommended that the manuscript be accepted after the suggested modifications.

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Reviewer #1: No

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-->PONE-D-25-32562R1-->-->Research on the Microscopic Mechanism of Water Immersion and collapsibility in Malan Loess with Different Particle Size-->-->PLOS One

Dear Dr. Mu,

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.

==============================

ACADEMIC EDITOR:-->-->

• Two new reviewers gave their detailed comments for quality improvement.
• Please carefully address their comments and clearly highlight the novelty of your study.

==============================

Please submit your revised manuscript by Feb 05 2026 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.. 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.. 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.. 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:

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• 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 . 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 . 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 . 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,

Jianguo Wang, PhD

Academic Editor

PLOS One

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If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise.

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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: All comments have been addressed

Reviewer #2: All comments have been addressed

Reviewer #3: (No Response)

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-->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: Yes

Reviewer #2: Yes

Reviewer #3: Partly

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

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

**********

-->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.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.-->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.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: Yes

Reviewer #3: Yes

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-->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: Yes

Reviewer #2: Yes

Reviewer #3: No

**********

-->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: Collapsibility of loess is a widespread, highly destructive geological hazard on the Chinese Loess Plateau. Malan loess exhibits distinct regional particle size variations, but the collapsible deformation characteristics and underlying microscopic mechanisms remain insufficiently. The manuscript research on the microscopic mechanism of water immersion and collapsibility in Malan Loess with different particle size, and the results could provide a theoretical basis for hazard mitigation. All the issures have been addressed.

Reviewer #2: General comment:

This article systematically investigates the collapsible deformation behavior and microscopic mechanisms of three types of Malan loess with different particle sizes. The experimental design is comprehensive, the descriptions are detailed, and the authors have addressed all points raised in the first round of review by revising the manuscript accordingly. Revisions include supplementing the geological background of sampling sites, standardizing the in-situ sampling procedures, and detailing the SEM testing protocol. The responses are generally thorough. However, deficiencies remain in the mechanistic explanations and comparative analysis with existing theories. The manuscript may be considered for publication after addressing the following points.

1.The title "Research on the microscopic mechanism of water immersion and collapsibility in Malan loess with different particle size" contains redundant wording "Research on". It is recommended to delete "Research on".

2.It is recommended to improve the clarity of all figures. Furthermore, there are inconsistencies: the sequence of Figure 1 (B) and (C) appears to be reversed; the content presented in Figure 6 (A) and (B) is inconsistent; Figures 7 and 8 are discontinuous. The authors are advised to carefully check all figures and their correspondence to the text.

3.It is recommended to provide details on how the physico-mechanical parameters in Table 1 were obtained (e.g., test standards, calculation methods).

4.In line 180, "initial height Ho" refers to the sample's initial height before loading. In line 191, "H0" is used again for the sample height after stabilization under each loading stage. To avoid confusion, it is suggested to use distinct notations.

5.The authors use formula (1) to calculate the collapsibility coefficient . Please clarify why this specific method was chosen. Is it based on a specific standard or theoretical framework? Supplementary explanation is needed.

6.In the SEM Test section, details were added per reviewer suggestions. However, some aspects require further clarification: In the line 206, what is the control criterion for "fully stirred uniformly" of the mixed curing agent? Also, specify the curing time and environmental conditions (temperature, humidity) for the soil sample during the curing process.

7.In the PCAS Test section, regarding the quantitative pore analysis of loess SEM images, how were the specific samples for analysis selected? Please justify how these analyzed samples are representative of the entire soil type

8.Line 254 states that "All samples exhibit a particle size range of 0.1-100 ". However, the particle size distribution curves in Figure 4 for all three loess types extend beyond 100 . The authors should check and clarify this apparent contradiction.

9.In line 257, "coarse-grained particles" refers to "fine sand and coarse silt". In line 265, "fine-grained particles" refers to "clay and fine silt". These descriptions are somewhat vague. Please provide specific size ranges for these particle categories

10.Line 265 states that the frequency curve peak for clayey loess is at "<20 ", yet Figure 4(C) suggests a peak at a size >20 . The authors should verify and correct this discrepancy.

11.In the Collapsibility deformation characteristics section, assuming H0 is the initial sample height, the observation that the collapsibility coefficient first increases and then decreases with increasing axial pressure implies, according to formula (1), that the axial deformation itself also first increases and then decreases with pressure. If this is indeed the case, it would be a notable finding. The authors should provide a clear physical explanation for this phenomenon.

12.In lines 192-193, the collapsibility test procedure involves saturating the sample by immersion after stabilization under the final load stage. As noted in the particle size analysis, clayey loess is dominated by fine particles. The high fine particle content can significantly affect the sample's permeability and the collapse during immersion. The authors could refer to studies like "DOI: 10.1007/s10064-025-04350-8" for a microscopic perspective on such effects.

13.In lines 363-365, the authors attribute the decrease in particle fractal dimension after collapse to changes in particle contact modes (e.g., point-to-point to point-to-edge), which simplifies particle boundaries. To better discuss the influence of particle morphology on particle crushing and subsequent changes in contact state, the authors could refer to relevant literature, such as: DOI: 10.1016/j.powtec.2024.120592 and DOI: 10.1016/j.powtec.2023.119204.

14.The authors propose a "particle-pore-clay synergistic collapsibility mechanism model". This model essentially describes structural changes in Malan loess before and after collapse. How does this model differ from existing collapse theories, particularly the structural theory mentioned earlier? A comparative analysis is recommended. Furthermore, for future work, analyzing collapse from a material damage perspective could be insightful. The authors may refer to: DOI: 10.1016/j.ijrmms.2024.106014.

15.Regarding engineering applications, the statement that the model "applies to loess engineering geology and disaster prevention, guiding foundation pre-treatment, assisting slope collapsible disaster prediction, and optimizing underground structure stability measures" is rather general. The authors should elaborate on how it can be specifically applied. For example, the authors may refer to DOI: 10.1016/j.tust.2025.107144, which first identifies influencing factors on construction conditions and then proposes specific application measures for given scenarios.

Reviewer #3: The manuscript entitled “Research on the Microscopic Mechanism of Water Immersion and Collapsibility in Malan Loess with Different Particle Size” presents a comparative investigation into sandy, silty, and clayey Malan loess using physical tests, SEM observations, and PCAS analysis to examine structure–property–mechanism relationships. The topic is relevant, the experimental scope is broad, and the manuscript is generally well organized. However, I believe the manuscript requires substantial revision before it can be considered for publication. My major concerns are listed below.

1. Although the manuscript proposes a “generalized collapse mechanism model,” the novelty and scientific contribution of this model remain unclear. Much of the mechanism discussion reiterates well-established structural interpretations of loess collapsibility. The authors should clearly articulate how their findings advance beyond existing theories and models in the literature, and specify what new insight is gained from the comparison of particle-size groups beyond descriptive differences.

2. The study relies on single sampling sites for each loess type, and the manuscript does not provide information on sample replication, intra-site variability, or experimental reproducibility. Without statistical measures (e.g., variance, confidence ranges, repeat test results), it is difficult to assess the reliability and regional representativeness of the findings.

3. The SEM observations and PCAS results are interesting, but the discussion remains largely qualitative. There is no analysis linking microstructural parameters to collapsibility outcomes (e.g., correlation, regression, sensitivity analysis). Similarly, fractal analysis is presented descriptively without deeper interpretation. Strengthening microstructure–mechanism–deformation connections would greatly improve scientific rigor.

4. Several key conclusions, especially regarding pore transformation, clay migration, and particle contact changes, are presented as deterministic mechanisms, yet the evidential basis is primarily visual observation. Additional explanation or quantitative justification is needed, particularly in Fig. 7–9 discussions. Consider integrating statistical comparisons, parameter references, or reviewing relevant SEM-based literature to reinforce interpretation.

5. Sections currently emphasize descriptive repetition rather than analytical synthesis. The authors should expand comparative discussion with prior studies (especially recent SEM/PCAS/fractal works) to demonstrate how their results align with or differ from established knowledge. Conclusions should be more concise, highlight the main contributions, acknowledge limitations, and avoid repeating results verbatim.

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-->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 published, this will include your full peer review and any attached files.). If published, this will include your full peer review and any attached files.). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

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-->PONE-D-25-32562R2-->-->The Microscopic Mechanism of Water Immersion and collapsibility in Malan Loess with Different Particle Size-->-->PLOS One

Dear Dr. Mu,

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ACADEMIC EDITOR: Please insert comments here and delete this placeholder text when finished. Be sure to:Be sure to:-->Be sure to:Be sure to:-->

• Minor reversions are still necessary.

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We look forward to receiving your revised manuscript.

Kind regards,

Jianguo Wang, PhD

Academic Editor

PLOS One

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Reviewers' comments:

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-->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 #2: All comments have been addressed

Reviewer #3: (No Response)

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

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Reviewer #2: Yes

Reviewer #3: (No Response)

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

Reviewer #2: N/A

Reviewer #3: (No Response)

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Reviewer #2: Yes

Reviewer #3: (No Response)

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Reviewer #2: Yes

Reviewer #3: (No Response)

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-->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 #2: My concerns and suggestions have been well addressed and I think the manuscript is ready for publication.

Reviewer #3: The authors have made a substantial effort to revise the manuscript and respond to the comments raised in the previous review round. Several important issues have been addressed. In particular, the manuscript now provides clearer descriptions of the sampling strategy, including the addition of parallel subsamples, which improves the reliability of the dataset. The authors have also expanded the discussion of the proposed mechanism and introduced additional quantitative parameters derived from PCAS analysis, which helps strengthen the link between microstructural observations and macroscopic collapsibility behavior. Overall, the revised version is clearer and more structured than the previous submission.

That said, a few aspects could still be improved before the manuscript is finalized. First, although the authors mention correlation and regression analyses between microstructural parameters and collapsibility indicators, the statistical presentation remains relatively limited. Providing more detailed descriptions of the regression results (e.g., fitting quality or statistical significance) would help better support the interpretations. Second, the discussion of SEM and PCAS results would benefit from a better explanation of how representative images or fields of view were selected, and how many observations were used in the quantitative analysis. Clarifying these points would strengthen the methodological transparency.

These remaining issues are relatively minor and can be addressed with small revisions. Overall, the manuscript now meets the general requirements for publication after minor revision.

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Reviewer #2: No

Reviewer #3: Yes:Zhiyuan He, PhDZhiyuan He, PhDZhiyuan He, PhDZhiyuan He, PhD

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The Microscopic Mechanism of Water Immersion and collapsibility in Malan Loess with Different Particle Size

PONE-D-25-32562R3

Dear Dr. Mu,

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.

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Kind regards,

Jianguo Wang, PhD

Academic Editor

PLOS One

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