Study on the Influence Mechanism of Sample Preparation Method on the Shear Strength of Silty Soil
Tymoteusz Zydroń
Round 1
Reviewer 1 Report
This manuscript investigated the impact of airport subgrade performance under different dry density and compaction processing method. A series of consolidated undrained shear test, nuclear magnetic resonance test and triaxial dynamic tests were carried out under different conditions, and then the effect of dry density and sampling method is revealed. The following comments need to be considered to further improve the quality of the manuscript.
1. How do the authors ensure the uniformity of the soil sample during sample preparation, especially for the compaction method? In addition, the soil sample disturbance may exist during soil demolding process. How to prevent it?
2. According to table 5, the samples are under unsaturated condition. The degree of saturation should be given in the text. Was the water in the sample drained out of the sample during compaction?
3. The continuous half-sine wave was used in loading process. However, the time between takeoff and landing of the aircraft should have a significant influence on the dynamic characteristics. How was the interval of the aircraft loading considered? Please clarify.
4. The dynamic loading test scheme is not clear. A figure of the loading waveform should be given. In addition, the authors should explain why the cycle vibration of N = 10000 times was selected as the termination condition.
5. The specimen saturation and drainage conditions for the static shear tests and dynamic triaxial tests appear to be different, please explain in detail.
6. The determination of resilient modulus should be clarified in lines 320-331.
Author Response
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Author Response.pdf
Reviewer 2 Report
This study carried out a series of compaction undrained shear test under different dry density and sample preparation methods and detailed reveal the mechanism of the differences from a microscopic perspective based on NMR tests. Afterwards, dynamic triaxial tests are carried out to verify the applicability of the findings in practical engineering situations. The article has detailed research and can guide the engineering project. Some of the following comments need to be addressed.
1. Table 3 etc, the degree of saturation is more suitable than water content.
2. On page 10, the application of dynamic loading is not clear. There should have a figure to show the specific dynamic loading procedures.
3. Figure 8: make clear that the results are at 10,000 cycles.
4. Lines 164 to 166. My recollection is that static pressing produces a different soil structure than kneading compaction and that is why behavior differs. See Jim Mitchells early work.
5. Due to the characteristics of aircraft loading, the dynamic loading frequency and waveform may be different from the actual situation. The authors are suggested to make a brief explanation for this difference.
6. Please update with related literature, e.g. Dynamic performance evaluation of airport subgrade under different compaction method.
Author Response
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Reviewer 3 Report
The results of geotechnical parameters of soil prepared by different methods is presented in the paper. The theme of the paper is interensting from the practical point of view but the paper needs some corrections. I have the following remarks:
1. I suggest to use grid in figure 1. It will make easier to interpret the data.
2. Figure 2 - I suggest to add the information about the relative compaction of the soil.
3. Authors should avoid using the term "cohesion force" and "cohesion stress". There is distinct diferrence between force and stress. Term cohesion is commonly used in the geotechnics and there is no need to change it. 6. Cohesion's unit is kPa, so it cannot be used the term "cohesion force"!
4. Lines 237-238: The state that the pore distribution differ slightly is not very informative. I suggest to use some test to state if the difference of pore distribution is relevant (Cremer-von Misses test for example). There is not
5. Figure 8-9: vertical axis should be the same for the right and left diagrams
6. The methodology of microstructure measurements should be clearly presented. The diameter and the height of the samples were both 1 mm. It means that sample volume is relatively small in reference to the soil samples prepared for the compression tests. I reckon that the location of sample taken from the soil could have impact on the measurements. Authors should precise how the samples for measurements of pore distribution were collected (from central part of the soil, upper part or another part of the sample?).
7. Line 273 - "the sample is not completely uniform before the test, there is still a large residual stress inside". The statement needs support with the use of the some papers.
I do not recommend the manuscript for publication in the present form. Authors should correct the text including the above remarks and the discussion of test results should be expanded.
Author Response
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Reviewer 4 Report
The authors worked on the influence mechanism of sample preparation method on the shear strength of silty soil. This manuscript is well structured and aligned with the current requirements of the research. Based on the review, it is concluded that this manuscript can be accepted for publication with revisions.
1、Most of the literature surveys have old research papers in Chinese, and minimal recent research has been considered. In order to understand the limitation of the existing research, authors are advised to include recent foreign research articles in the introduction and present the literature's limitations and the study's needs.
2、Another important limitation of the manuscript is that the entire result and discussion section is written without reference to the existing literature. It would be good to read the reasoning supporting the present proof of concepts. Please compare the obtained data with the codes and research articles.
3、There are obvious differences in cohesion of samples prepared by the two sample preparation methods. What factors lead to this？Why is the cohesion of samples prepared by static compression method almost completely lost close to 0 under high density.
4、Cohesion is a manifestation of internal molecular force, just use cohesion, not macroscopic force. Please standardize the relevant English expressions.
5、Figures and tables should be made more standardized. The horizontal coordinates in Figure 1 are overlapped, and the dividers in Table 1 are of different thickness. The ordinate subscript in Figure 3 is not marked correctly, and the dry density in the legend should be "ρ" instead of "r".
6、It would be nice to have photographs of specimens prepared by different methods as well as samples in NMR.
7、How is the significant change of pore structure of specimens prepared by static compression method before and after shear related to the residual stress? Is the residual stress the only factor leading to the structural change?
Author Response
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Reviewer 5 Report
Dear Editor/Authors
In the present research, the author investigated the influence of sample preparation method on the shear strength of silty soils by carried out the consolidated undrained shear test (CU test) and nuclear magnetic resonance microscopic test on the soils. The essential characteristics of the research program are reported and the figures and tables were carefully prepared. But the manuscript needs some further improvements in its structure and language. There are some grammatical errors through the manuscript. Some specific comments that might be helpful for the authors to enhance the quality of the manuscript are as follow:
1. The abstract is long and it needs to be summarized.
2. The introduction is written in detail.
3. It would be better to highlight major difficulties and challenges, and your original achievements to overcome them, in a clearer way in abstract and introduction.
4. Sampling, specimen preparation, and test procedures must be referenced to suitable standard methods such as ASTM, BS, etc.
5. In general, Discussion is well written. Nevertheless, the discussion should provide a summary of the main finding(s) of the manuscript in the context of the broader scientific literature, as well as addressing any limitations of the study or results that conflict with other published work.
6. The “Conclusions” reports methodology and some results of the research. It is better that it is provided without paragraph numbering.
7. Please check and improve the English throughout the paper. The English language of the paper needs to be improved.
Best Wishes
The end
Author Response
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Author Response File: Author Response.pdf
Reviewer 6 Report
CONFIDENTIAL REVIEW COMMENTS
Manuscript ID# sustainability-2148477
Manuscript Title # Study on the Influence Mechanism of Sample Preparation 1 Method on the Shear Strength of Silty Soil
The entire manuscript did not distinguish between the effect of the methods of sample preparation and the effect of the compaction types on the soil performance. And, the introduction of the research went in a direction other than the objectives of the research. Beside the paper did not provide originality, the methodology was not designed properly to reach the study aim. Moreover, the differences in the shear strength and other parameters can be attributed mainly to the anisotropic behavior, and this is what this research ignored unfortunately.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
I have no comments to the text of manuscript. The authors answers to my remarks are satisfying.
Author Response
Thanks for the valuable comments. No further response has attached since no comment was received.
Reviewer 5 Report
Dear Editor,
I checked the changes made by authors on the manuscript. The authors have truly improved the manuscript based on my comments. So, the paper can be accepted for publication now.
Yours faithfully
Author Response
Thanks for the valuable comments. No further response has attached since no comment was received.
Reviewer 6 Report
It is important to mention the effect of anisotropy on the strength of soil.
Therefore, it is recommended to use the below article for that:
Al-Rkaby, A. H., Chegenizadeh, A., & Nikraz, H. R. (2019). An experimental study on the cyclic settlement of sand and cemented sand under different inclinations of the bedding angle and loading amplitudes. European Journal of Environmental and Civil Engineering, 23(8), 971-986.
Al-Rkaby, A. H., Nikraz, H. R., & Chegenizadeh, A. (2017). Stress and deformation characteristics of nonwoven geotextile reinforced sand under different directions of principal stress. International Journal of Geosynthetics and Ground Engineering, 3(4), 1-11.
Author Response
Thanks for the recommendation. The references have been reviewed and added.
