Cyclic Behaviour of Uniform Sand in Drained and Undrained Conditions at Low Confining Stress in Small-Scale Landslide Model

Round 1

Reviewer 1 Report

The manuscript is concerned with cyclic behavior of uniform sand in drained and undrained conditions at low confining stress, which is interesting. It is relevant and within the scope of the journal. However, the manuscript, in its present form, contains several weaknesses. Adequate revisions to the following points should be undertaken in order to justify recommendation for publication.

 

1.      In the first place, I would encourage the authors to rewrite the abstract by enhancing the objective of the present study and extending more with the key results. As it is, the abstract is a little thin and does not quite convey the interesting results that follow in the main paper. The "Abstract" section can be made much more impressive by highlighting your contributions. The contribution of the study should be explained simply and clearly.

2.      The "Introduction" section needs a major revision in terms of providing more accurate and informative literature review and the pros and cons of the available approaches. Also, the motivation and contribution should be stated more clearly.

3.      In the conclusion section, the limitations of this study should be highlighted.

4.      Moreover, the manuscript could be substantially improved by relying and citing more on recent literatures about landslide early warning such as the followings. 10.1007/s10346-022-01923-6, 10.1016/j.engappai.2022.105150. Discussion or incorporation of those concepts in your works are encouraged.

5.      Grammatical issues in the manuscript should be corrected.

6.      The first letters in Line 67 (behaviour) line and 188 (because) should be in capital letter.

7.      Mechanical properties of the sand should be provided.

8.      Scaling factor of 40 was adopted in the present study. What are other feasible alternatives? What are the advantages of adopting this case study over others in this case? How will this affect the results? The authors should provide more details on this.

9.      Equation 10: displaying error.

10.   Figure 5: please change the color pattern for fine, medium, and coarse sands for better visualization.

11.   It is shown in the reference list that the authors have several publications in this field. This raises some concerns regarding the potential overlap with their previous works. The authors should explicitly state the novel contribution of this work, the similarities, and the differences of this work with their previous publications.

Author Response

Dear Reviewer,

The Author would like to thank for the time and support to make this manuscript clearer and more interesting to the readers. We are trying to improve or noticed parts of the manuscript according to the Reviewer’s comments and requests.

 

 

Responses to Reviewer 1:

 

1. In the first place, I would encourage the authors to rewrite the abstract by enhancing the objective of the present study and extending more with the key results. As it is, the abstract is a little thin and does not quite convey the interesting results that follow in the main paper. The "Abstract" section can be made much more impressive by highlighting your contributions. The contribution of the study should be explained simply and clearly.

 

 

The Abstract has been altered to more highlight the contribution of this research. Altered abstract is as follows:

 

Earthquakes are one of the main landslides triggering factors. Earthquake induced cyclic shear stresses and strains in a soil generating the rise of pore water pressure and soil strength degradation that tends toward the slope failure. Slopes in which shallow landslides can be formed due to geological conditions are most susceptible to such kind of failures mainly because of low confining stress. The confining effective stress has a significant role on a soil response during static and cyclic loading. Under low confining stress, soil exhibits dilatant behavior and can degrade rapidly under cyclic loading.

This paper presents the results of undrained and drained cyclic triaxial tests on uniform sandy soil material used for modelling small-scale shallow landslides under 1g conditions. Based on the scaling laws for a model in for 1g conditions, the frequencies of straining amplitudes for strain-controlled cyclic triaxial tests were defined. Undrained and drained cyclic triaxial tests on the type of sand used in a small-scale landslide model were performed. The sandy samples were previously consolidated at the low confining stress which corresponds the values of present in shallow landslide used as prototype.

The influence of loading frequency and low confining stresses on sand behavior was investigated and the simple models for pore pressure build-up and volumetric strain sand behavior was proposed. These simple models can be used to estimate   increasing of pore water pressure and volumetric strain due to the cyclic loading at low confining stress for frequencies lower than 1 Hz.

The proposed models show good correlation with the data obtained in the laboratory test.

            .

 

2. The "Introduction" section needs a major revision in terms of providing more accurate and informative literature review and the pros and cons of the available approaches. Also, the motivation and contribution should be stated more clearly.

 

Thank you for this comment. Introduction section has been reviewed and pros and cons are stated more clearly.

 

Motivation and contributions have been added as it follows:

 

The main motivation for carrying out this research was to determine behavior of sandy soil, which is going to be used for small-scale physical slope model in 1g conditions, under cyclic loading. The results of conducted undrained and drained cyclic triaxial tests on such sandy soil material under dynamic loading are presented, as well as the proposed models for pore water pressure build-up and volumetric strain behavior. The proposed models would be used in quick determination of the pore water pressure ratio and volumetric strain behavior of sandy soils, at low confining stresses.

 

3. In the conclusion section, the limitations of this study should be highlighted.

 

Thank you for this comment. Limitations of the study have been addressed as it follows:

 

 

The main limitations of the study results lay in limited using of proposed models to the uniform sandy soils and the field of applied loading frequencies to the values of 0.5 Hz that correspondent to maximal values used in small-scale slope testing at shaking table. For other types of soil material, especially for those with higher content of fine particles, additional triaxial test should be conducted, using procedures described in this manuscript.

 

4. Moreover, the manuscript could be substantially improved by relying and citing more on recent literatures about landslide early warning such as the followings. 10.1007/s10346-022-01923-6, 10.1016/j.engappai.2022.105150. Discussion or incorporation of those concepts in your works are encouraged.

 

Thank you for the suggestion. Although the manuscript is not related to landslide early warning system we added a section to address your comment as follows:

 

Although the main intention of this manuscript is not related to use the proposed models in development landslide susceptibility analyses [e.g., 46 – 48], early warning systems [e.g., 49 – 51], as well as other issues such are stability and run off landslide predictions [52,53], proposed models would be useful tool in such analyses.

 

5. Grammatical issues in the manuscript should be corrected.

 

The manuscript has been properly verified and modified for English grammar.

 

6. The first letters in Line 67 (behaviour) line and 188 (because) should be in capital letter.

 

Accepted.

 

7. Mechanical properties of the sand should be provided.

 

Mechanical properties are provided with added Table 4

 

 

8. Scaling factor of 40 was adopted in the present study. What are other feasible alternatives? What are the advantages of adopting this case study over others in this case? How will this affect the results? The authors should provide more details on this.

 

In any physical modelling the first step is to decide the size of the model related to the prototype. In this study, the scaling factor was selected related to the limitation of the shaking table (mass limit is approximately 130 kg), while the size of the prototype is used as a slope of 20 m that is an average length of landslides near the infrastructure in Croatia that were accepted as authoritative size of landslides within the noticed funding Project. The answers to the other questions were discussed in numerous literature and would require significant explanations that are not considered as a part of this manuscript, but are noticed in cited literature (15 – 38): The Authors’ opinion is that these explanations would burden the manuscript and should be avoided.

 

 

9. Equation 10: displaying error.

 

There is no displaying error. It is a one way of mathematical nomenclature. Authors have decided to change the “square” symbol to simpler one, letter “j”.

 

 

10. Figure 5: please change the color pattern for fine, medium, and coarse sands for better visualization.

 

Color patter has been changed to a darker shade for fine, medium, and coarse sands.

 

11. It is shown in the reference list that the authors have several publications in this field. This raises some concerns regarding the potential overlap with their previous works. The authors should explicitly state the novel contribution of this work, the similarities, and the differences of this work with their previous publications.

 

The results presented in here were not presented in publication referenced in the manuscript. All referenced manuscripts related to this study presented results of small-sale slope test in which rainfall was the landslide triggering factor, that is clearly visible in the titles of cited manuscripts. So, the Authors do not consider as necessary to explicitly state the novel contribution of this work, the similarities, and the differences of this work with previous referenced publications.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript presents results from physical tests of a small-scale landslide model under drained and undrained conditions for considering shallow landslides triggered by earthquakes.  Although the science is strong, the manuscript requires extensive English language modifications to be suitable for publication.  Attached are suggested comments regarding the language, however the manuscript would benefit from extensive modifications and revisions of the grammar.  Contrastingly, the technical content of the manuscript is well researched, with some minimal recommendations also provided on the pdf attached.

Comments for author File: Comments.pdf

Author Response

Responses to the Reviewer 2:

Dear Reviewer,

The Author would like to thank for the time and effort to make this manuscript clearer, more legible and more interesting to the readers. We are trying to improve or noticed parts of the manuscript according to the Reviewer’s comments and requests. The manuscript is completely edited and grammatically checked and we hope that is now more legible.

 

 

1. This sentence is poorly worded.

Thank you for the comment. The Abstract is completely revised and rewritten.

2. This sentence is poorly worded.
3. Thank you for the comment. The Abstract is completely revised and rewrited.
4. This sentence is identical to the first sentence of the abstract

The sentence is rephrased

5. This sentence is virtually the same as the second sentence of the abstract

The sentence is rephrased.

6. Poorly worded

The sentence is rephrased.

7. The author’s experiences is a claim with minimal qualification. References to technical papers is preferable.

Thank you for this comment. The sentence is rephrased and references are added.

8. Sentence poorly worded

The sentence is rephrased and appropriate article added.

9. till is not a word

Thank you for this comment. The Authors are aware about this mistake which was unfortunately noticed after submission.

10. What is the distinction between (a) and (b) here?

Shape under (a) is considered as an input. In this case it is only “Geotechnical model”. Shape (b) is considered as the decision part where researcher can decide whether to do a numerical od physical model.

11. why 40?

In any physical modelling the first step is to decide the size of the model related to the prototype. In this study, the scaling factor was selected related to the limitation of the shaking table (mass limit is approximately 130 kg), while the size of the prototype is used as a slope of 20 m that is an average length of landslides near the infrastructure in Croatia that were accepted as authoritative size of landslides within the noticed funding Project. The answers to the other questions were discussed in numerous literature and would require significant explanations that are not considered as a part of this manuscript, but are noticed in cited literature (15 – 38): The Authors’ opinion is that these explanations would burden the manuscript and should be avoided.

12. "more significant" is confusing. Either something is significant or it is not.

Thank you for this comment. As it is suggested, the Authors removed “more” in front of “significant”

13. e. or e.g.?

Thank you for this comment. Everything was changed to “e.g.”

14. What are these squares here? Looks like there has been an issue with the conversion to pdf format.

There is no displaying error. It is a one way of mathematical nomenclature. Authors have decided to change the square symbol to simpler one, letter “j” to avoid misunderstandings.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper entitled “Cyclic behaviour of uniform sand in drained and undrained conditions at low confining stress in small-scale landslide model” is an interesting study that presents results of an undrained and drained cyclic triaxial test on sandy material in order to define a physical model of a shallow landslide in 1g conditions.

I read carefully the manuscript. In my opinion, the paper could be suitable for publication taking into account the following suggestions/comments:

a) “Sustainability” is an international journal of studies relating to sustainability and sustainable development. Therefore, the paper should more focus on these topics. Authors need to improve their manuscript in view of sustainability.

b) In the introduction (Line 34), about the importance of physical models at 1g, authors may consider also the following paper:

Salvo Grasso, Valentina Lentini and Sammito Maria Stella Vanessa. A new biaxial laminar shear box for 1g shaking table tests on liquefiable soils. 4th International Conference on Performance-based Design in Earthquake. Geotechnical Engineering (PBD-IV) in Beijing, China, 15-17 July 2022.

c) Figures 1,8,11,12,15 are challenging to read.

d) In p. 5 Line 129, author should specify the earthquake that will be applied to the small-scaled landslide, being it reported in Figure 2.

e) Does the prototype of the slope reported in Figure 2 refer to Grohovo Landslide?

f) Check the language style in 67, 188 and 230 Lines.

g) In Figure 8 and Line 255-256, to which yellow and green marks do the authors refer?

Author Response

Responses to the Reviewer 3:

Dear Reviewer,

The Author would like to thank for the time and effort to make this manuscript clearer, more legible and more interesting to the readers. We are trying to improve or noticed parts of the manuscript according to the Reviewer’s comments and requests. The manuscript is completely edited and grammatically checked and we hope that is now more legible.

 

1. “Sustainability” is an international journal of studies relating to sustainability and sustainable Therefore, the paper should more focus on these topics. Authors need to improve their manuscript in view of sustainability.

 

The Authors’ opinion is that the submitted manuscript is suitable of publishing in Special Issue of “Sustainability” titled “Soil Dynamics and Earthquake Engineering in Sustainability”. Presented results in this manuscript are focused on the cyclic behavior of material under low confining stress which correspond to the slopes that have a potential of forming shallow landslide. The manuscript is providing an information on how the slope, which can be saturated by rainfall for example, can fail due to cyclic loading which would have social and economic repercussions, thus relating to sustainability. The results presented in manuscript is also important for the sustainable development regarding the potential of landslide activation of slopes near urban areas which is significant to urban planning, as well as mitigation and remediation of slopes prone to sliding in seismic conditions.

 

2. In the introduction (Line 34), about the importance of physical models at 1g, authors may consider also the following paper:

 

Salvo Grasso, Valentina Lentini and Sammito Maria Stella Vanessa. A new biaxial laminar shear box for 1g shaking table tests on liquefiable soils. 4th International Conference on Performance-based Design in Earthquake. Geotechnical Engineering (PBD-IV) in Beijing, China, 15-17 July 2022.

 

Thank you for this comment and suggestion. The paper is considered, noticed and cited in the manuscript.

 

3. Figures 1,8,11,12,15 are challenging to read.

 

Thank you for the comment. The font size in suggested figures is enlarged and figures itself are made larger.

 

4. In p. 5 Line 129, author should specify the earthquake that will be applied to the small-scaled landslide, being it reported in Figure 2.

 

Thank you for the comment. The earthquake record sketched in Figure 2 is only a symbolical representation. This is only a sketch. The future research considers a small-scale slope model and will deal with the detail specification of earthquake record.

 

5. Does the prototype of the slope reported in Figure 2 refer to Grohovo Landslide?

 

No, prototype of the slope reported in the Figure 2 is only a sketch of the type of slopes with a potential of forming shallow landslide; it is ordinary slope profile.

 

6. Check the language style in 67, 188 and 230 Lines.

 

The whole manuscript has been properly edited and modified for English grammar.

 

7. In Figure 8 and Line 255-256, to which yellow and green marks do the authors refer?

 

Thank you for the comment. The marks in the figure were previously yellow and green but was decided to alter the color before original submit. The Authors are aware about this mistake which was unfortunately noticed after submission.

Round 2

Reviewer 1 Report

The comments have been carefully addressed. Accept as it is.

Reviewer 2 Report

As per the revisions, I am happy with the quality of the revised manuscript.

Reviewer 3 Report

The authors took into account the suggestions, improving the quality of the submitted article.