Response of Sandy Soil–Water Migration to Different Conditions under Unidirectional Freezing

Round 1

Reviewer 1 Report

In this study, the indoor soil column test device is applied to carry out the one-way indoor freezing test of unsaturated soil, and studied the response of soil sample water migration to different freezing temperature, initial moisture content, soil density, freezing time, solute concentration and solute type conditions. The authors have done some work and come to some conclusions. However, the author analyses in a rather one-dimensional way and the article still has some problems. Here are the questions that need to be improved or answered:

1. What is the basis for the reagent parameters set in Table 1? Are there references to support this?

2. Concentrations were set to 0.2 mol/l and 0.3 mol/l in the experiment; is this a large enough difference? Moreover, from Figure 8, the difference between the two results seems to be small.

3. Does the fact that there is only one set of test samples for each condition in the experiment make the conclusions less reliable?

4. The format of the reference list in the paper is not uniform. It is recommended to check and revise according to the requirements of the journal.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This is an interesting study that explores the effects of different freezing temperatures, initial water content, soil density, freezing time, solute concentration and solute type on permafrost water migration, and here are some of the questions I asked:

1, Solute has been added, why not consider the solute movement process under permafrost conditions together?

2, Table 2, why choose these temperatures, I did not understand, this is a common temperature in the northeast, why the 10th group of experimental time for 198h

3, after compaction in layers, can the original capacity still be guaranteed, the author's description here does not make sense.

4, only two temperatures, capacity and weight conditions, is too little, the author only 10 groups of experiments, if combined with numerical modelling, whether it would be more convincing

5, Chapter 3.7 the existing picture, not enough to support the conclusion of the text, that CaCl2 affects the water movement is too one-sided

6. If it is not discussed in the article, can you explain the difference between this study and other studies?

7, the references in the article are not enough to support a thesis, and the thesis needs to be added to complete.

Moderate touching up of the English language is required

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

1. I suggest rewriting the findings in the abstract into three or four sentences rather than very long 8-10 line sentence. Likewise, in the conclusion, I suggest rewriting experimental findings into bullet points.

2. In line 68, authors mention the word "foreign scholars". It is suggested to rewrite the sentence without mentioning this word.

3. In line 109, I think the authors mean "TDR sensor..... to record real-time". Instead they wrote "to make real-time".

4. How were different soil densities achieved? Did authors use a packing tool or different soil type?

5. 2 mm screen and 0.25 mm screen usage was mentioned in page 2 and page 4. Can authors clarify which one was used for what purpose? They can state that in section 2.3.

6. Was there insulation on the bottom of the test bed? If not, there is scope for heat leaks from the ambient.

7. For test results corresponding to fig. 2 and 3, authors must mention what soil sample was used.

8. Takeaways from cited references in line 199-201 appear contradictory. One says the waterfront moves downwards and the other says it moves upwards. Can authors clarify and rewrite this?

9. Influece of many different parameters was lasted which is good. But did you also test the influence of soil permeability? This is an important parameter. Otherwise, they can list findings from other published studies if available.

Minor editing of language is suggested. There are some longer sentences which could confuse the reader. Suggested to break them down into smaller sentences.

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Dear Editor(s);

Sustainability,

Manuscript ID: Sustainability-2511556

Title: Response of unsaturated soil water migration to change control conditions under unidirectional freezing

1- The title of the manuscript is better to be revised. Kindly reconsider and rewrite the parts "unsaturated soil water migration" and "to change control conditions".

2- The English writing style is not favorable. There are several spelling and grammatical errors in the manuscript. The writing style of the paper is moderate and should be improved. It is preferred to professionally revise the paper regarding editorial and grammatical rules particularly a native English to avoid such errors.

3- Kindly rewrite part (2) in the Abstract section. This part is waging with hard sentences since there is only one very long sentence. Further, kindly avoid writing very long sentences all over the manuscript.

4- What is the element of novelty of this paper? Who will benefit from the research and how it should be beneficial in future research? The necessity of performing the research should be better emphasized in the abstract, introduction, and conclusion sections despite relying on "the effects of different solute concentrations and solute species" and further than that. In addition, it seems you can explain more about the gap and introduce the importance of your research and contributions at the end of the introduction.

5- The "Introduction" part:

5-1- It is important to note the role of changes in the soil strength properties with respect to the detrimental effects of freeze-thaw cycles in frozen regions. Using recent relevant publications may be helpful, especially for the introduction section:

An elastic-viscoplastic model for saturated frozen soils. https://doi.org/10.1080/19648189.2016.1271361.

Constitutive model for rate-independent behavior of saturated frozen soils. https://doi.org/10.1139/cgj-2015-0467.

5-2- The micro- and macro-structures and microscopic mechanisms of the soil, formation, and development of cracks are better added in the introduction to benefit our readers and provide further narrative results and discussion. To this end, I would like to bring your attention to the following papers for your inclusion in the background to reinforce/echo the usefulness of your manuscript:

Effects of thermal cycles on microstructural and functional properties of nano treated clayey soil. https://doi.org/10.1016/j.enggeo.2020.105929.

Effects of A low-carbon emission additive on mechanical properties of fine-grained soil under freeze-thaw cycles. https://doi.org/10.1016/j.jclepro.2021.127157.

In other words, the above comments are intended to highlight the importance of these issues in areas that have experienced the devastating effects of freezing or freeze-thaw cycles.

6- The classification of the soil and its grain size distribution curve must be provided. Engineering properties and chemical composition of the soil also should be presented.

7- Is it better if the "One-way" terms for "One-way soil freezing test" were changed to "One-direction"?

8- Line 136: When you spray the soil sample with an appropriate amount of water and rest it for 48h, how can you be sure about evaporation water and reaching the desired moisture content before performing tests, because of resting for 48h? Note that this item (moisture content value) has a significant effect on water migration.

9- Table 2: What are the main criteria for choosing these freezing ranges of temperatures? The main reason and criteria should be mentioned in the manuscript.

10- Figs. 2 & 3: What are those sudden changes in the curve around 90-100 hours?

11- Line 178: What did you mean by "in different soil"?

12- Line 188: It seems the changing trend of soil water content for these samples is not obeying a similar trend. What happened to the water content around 20 cm under -35°C?

13- The dashed line related to the "Initial water content" also should be added to the legend of Fig. 4. The same issue for Figs. 6 and 9.

14- Please re-organize the short paragraphs. It is recommended that these paragraphs be merged with the related long paragraphs. Kindly also avoid writing very long sentences.

15- Line 249: "under different soil densities" should be changed to "under different freezing times".

16- Fig. 7: The authors compared samples under 104h and 198h. 198h was not in the program testing schedule. Why didn't you compare the lower, moderate, and ultimate times?

17- Line 267: You need to mention "for different solute concentrations" in this part. In Line 248: "for different solute species" needs to be added.

18- A conclusion is not merely a summary of your points or a re-statement of your research findings but a synthesis of key points. It should help the readers understand why your research should matter to them after they have finished reading the paper. Kindly make sure your conclusions section underscores the scientific value added to your paper.

The English writing style is not favorable. There are several spelling and grammatical errors in the manuscript. The writing style of the paper is moderate and should be improved. It is preferred to professionally revise the paper regarding editorial and grammatical rules particularly a native English to avoid such errors.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The author has revised and responded to my last comment and the article has gained some degree of improvement. But there is one question that the author didn't explain clearly.

In the last review I asked a question: Concentrations were set to 0.2 mol/l and 0.3 mol/l in the experiment; is this a large enough difference? Moreover, from Figure 8, the difference between the two results seems to be small.

The authors replied: Thank you very much for your opinion. After our test and determination, the difference between the results is not very big.

Since the difference in results is not that great, does it adequately justify the conclusions within the paper? In other words, are the conclusions drawn therefrom sufficiently reasonable? It is recommended that the author explain this clearly.

Author Response

Thank you very much for your comments. We are really sorry that we did not notice the modification of this problem and missed this part in the article. Now the content of the article has been modified.

Author Response File: Author Response.docx

Reviewer 2 Report

I suggest adding experiments to the manuscript. The existing experiments could not support the whole manuscript, and there were too many loopholes in the experimental design to understand the rationality of the experiment. The author's response to the last review comments could not convince me, they did not give a better explanation of the problem, they did not seriously explain the reasons in the manuscript, and they did not discuss them.

Author Response

Thank you very much for your suggestion. We are very sorry that there are some deficiencies in our experimental design. However, due to some restrictions, we cannot do more experiments at present. In the future, we will add more experiments based on your suggestions and continue to improve our results.

Reviewer 3 Report

Authors have provided satisfactory explanation. The manuscript can be proceeded for publication.

Author Response

Thank you very much for your recognition.

Round 3

Reviewer 2 Report

I'm sorry, but I personally feel that the experiments must be in three or more groups, and in all the time I've been reviewing the manuscript, the authors have had complete time to add new experiments, and only two groups of experiments are not comparable at all.

Author Response

Please check the attachment.

Author Response File: Author Response.docx