Dynamic Characteristics of Post-Cyclic Saturated Loess

Round 1

Reviewer 1 Report

Review for Applied Sciences Journal on the manuscript entitled: "Dynamic characteristics of post-cyclic saturated loess".

Qian Wang * , Yan Wang , Wenguo Ma , Dongwang Tao

Here are some of my comments or suggestions in detail:

"The impaction of the OCR on the kinetic parameters of the loess after shock is analyzed." what did you mean by "kinetic parameters"?

"a pre-shock-reconsolidation test are designed to simulate", what did you mean by pre-shock tests?

Figure 4: I think x-axies title is not clear, I suggest to change it to (percent passing %).

Could you please classify the soil used?

"Table 1. Physical properties of the tested loess." how the density was measured?

 This methodology section is so long, I suggest to summarize it.

Figure 15: the microstructural changes is not clear, I suggest re-presenting the SEM results in a way that is clearer and supports the discussion (add arrorrws, more clear pictures). 

  "In purpose of studying the impaction of OCR on the nonlinear kinetic parameters of the postseismic saturated loess, the OCR are set as 1, 2, 3 and 4." Could you please how the OCR was fixed (1,2,3,4) in the dynamic and static conditions?     "The relation of the Gd /Gdmax versus the γd of the pre-shock saturated loess under different reconsolidation conditions is shown in Figure 9."  Do you mean after or pre-shock? please check.

Author Response

1. "The impaction of the OCR on the kinetic parameters of the loess after shock is analyzed." what did you mean by "kinetic parameters"?

Thanks for the reviewer’s comments. The “kinetic parameters” may misuse. We have changed it to” dynamic parameters”. Please check it.

 

2. "a pre-shock-reconsolidation test are designed to simulate", what did you mean by pre-shock tests?

Thanks to the referee. The pre-shock tests are a series of cyclic shear tests to simulate the seismic action. The amplitude of the dynamic load is calculated using equation (1) and equation (2) in the revised manuscript, which is based on strong earthquakes with different intensities. The detail of the tests is provided in paragraph 1 and 2 in section 2.3. Please check it.

 

3. Figure 4: I think x-axies title is not clear, I suggest to change it to (percent passing %).

Thanks to the referee. I think your comment is the title of the Y-axis. The Y-axis title of Figure 4 is modified as percent passing / %. Please check it.

 

4. Could you please classify the soil used?

Thanks to the referee. According to the Casagrande plasticity chart, the soil used in this study is CL. We added it in the first paragraph on page 6. Please check it.

 

5. "Table 1. Physical properties of the tested loess." how the density was measured?

Thanks to the referee. The density of the loess was measured using the cutting ring method based on the Chinese Code GB50123-2019.

 

6. This methodology section is so long, I suggest to summarize it.

Thanks to the referee. We have removed some sentences that are not essential in sections 2.1 and 2.2 to make sure the methodology section is more concise. Please check it in the revised manuscript.

 

7. Figure 15: the microstructural changes is not clear, I suggest re-presenting the SEM results in a way that is clearer and supports the discussion (add arrorrws, more clear pictures).

Thanks for the reviewer’s valuable comments. The SEM results shown in Figure 15 are not clear. We have added some labels on the SEM images and enlarged the photos to make sure it is clear. The improved images are shown in Figure 15 in the revised manuscript. Please check it.

 

8. "In purpose of studying the impaction of OCR on the nonlinear kinetic parameters of the postseismic saturated loess, the OCR are set as 1, 2, 3 and 4." Could you please how the OCR was fixed (1,2,3,4) in the dynamic and static conditions?

Thanks to the referee. During the dynamic triaxial tests, the consolidation conditions of specimens with each OCR are simulated based on the determined axial pressure. When the OCR=1, the axial pressure is calculated by the density and depth of the loess layer, and the confining pressure is the same as the axial pressure in this study. When the OCR=2, it means the axial pressure and the confining pressure is 2 times those when the OCR=1. This test method is introduced in the literature [26], please check it.

 

9. "The relation of the Gd /Gdmax versus the γd of the pre-shock saturated loess under different reconsolidation conditions is shown in Figure 9." Do you mean after or pre-shock? please check.

Thanks to the referee’s precise comments. The words “after or” is missing. We have added it to the revised manuscript. Please check it.

Many thanks to Reviewer 1 for your valuable comments.

Reviewer 2 Report

Reviewer’s comments

1.      Abstract to include important concluding remarks in the last portion of abstract.

2.      Figure 1 Landslide area/ Mudflow area to be encircled for better understanding and clarity in (a) and (b)

3.      Please include following citations with respect to keywords:

# Re-liquefaction resistance of lightly cemented sands

#Dynamic properties of Tianshui saturated remolded loess: A laboratory loess: A laboratory study

# Effects of nonplastic fines on static liquefaction of sands.

#Static and dynamic behavior of collapsible soils

# Dynamics stress–strain behavior of Tianshui soils. Landslides

#Predictive models for normalized shear modulus and damping ratio of modeled rockfill materials.

# Impact of economic development levels and disaster types on the short-term macroeconomic consequences of natural hazard-induced disasters in China.

#The influence of land urbanization on landslides: An empirical estimation based on Chinese provincial panel data.

4.       Please include paragraph the need for future research in the discussion session.

5.       Please provide at least two cites where test instruments are used for similar study.

6.      Seismic activity/ Earth quake occurred couple of decades back before this study was undertaken. Was there any further natural activity such as weathering, natural water table in the area which can have impact on Soil structure /the area of study. Authors are requested to provide assumptions, limitation of study.

7.      Aim or objective of study to be stated which can be correlated with conclusion.

 

Comments for author File: Comments.pdf

Author Response

1. Abstract to include important concluding remarks in the last portion of abstract.

Thanks for the reviewer’s valuable comments. Some of the important conclusion is missing in Abstract. We have added those in the last portion of abstract. The grammar mistakes are still checked and revised. Please check it. The following are the revised abstract:

Damage to soil structure caused by strong earthquakes is one of the main reasons for post-earthquake geohazard development. To investigate the nonlinear dynamic behaviors of the post-earthquake loess, a pre-shock-reconsolidation test is designed to simulate the process of the loess undergoing earthquake and post-earthquake reconsolidation in the natural state. Besides, dynamic triaxial tests of the specimens before and after pre-shock action and consolidation stabilization with different over-consolidation ratios (OCR) are conducted to investigate the variety of the dynamic modulus and damping ratio of the saturated loess. The influence of pre-shock and reconsolidation on the dynamic behaviors is determined. Moreover, the mechanism of the changes after pre-shock and consolidation is discussed by combining the microstructure test results of soil samples before and after pre-shock and reconsolidation. The results suggest that the kinetic stiffness of the pre-shock saturated loess decreases significantly under the same consolidation conditions. The growth of the damping ratio- dynamic strain curve increases, and the deformation potential of the loess has a remarkable growth. With the increase of OCR, the dynamic elastic modulus after pre-shock increases continuously, however, the damping ratio decreases significantly. The dynamic stiffness increases and the deformation potential weakens significantly. The strong earthquake leads to the weakening of inter-particle cementation, pore penetration, and structural reorganization in the local area, which makes a significant decrease in the dynamic shear modulus ratio and an increase of the damping ratio of the loess, leading to the enhancement of soil dynamic nonlinearity and the attenuation of the dynamic strength. Moreover, the compaction effect of reconsolidation on the soil increases the inter-particle friction and heals some microfractures, which leads to an increase in soil stiffness. Thus makes the maximum dynamic shear modulus and the maximum dynamic shear stress amplitude of the post-cyclic saturated loess perform at the same level compared with the natural loess without shock when the OCR=3. However, the dynamic shear modulus and the damping ratio of the post-cyclic saturated loess are close to which of the natural loess when the OCR=2.

 

2. Figure 1 Landslide area/ Mudflow area to be encircled for better understanding and clarity in (a) and (b).

Thanks for your comment. The figure was modified based on your comments. The landslide area and mudflow area of the two landslides are encircled in a red line. Besides, the satellite imagery of the landslides is added based on other reviewers’ suggestions. The location of the landslides is shown in Figure 2. We believe these modifications may help the readers better understand the disasters. Please check it in the revised manuscript.

 

3. Please include following citations with respect to keywords:

# Re-liquefaction resistance of lightly cemented sands

#Dynamic properties of Tianshui saturated remolded loess: A laboratory loess: A laboratory study

# Effects of nonplastic fines on static liquefaction of sands.

#Static and dynamic behavior of collapsible soils

# Dynamics stress–strain behavior of Tianshui soils. Landslides

#Predictive models for normalized shear modulus and damping ratio of modeled rockfill materials.

#Impact of economic development levels and disaster types on the short-term macroeconomic consequences of natural hazard-induced disasters in China.

#The influence of land urbanization on landslides: An empirical estimation based on Chinese provincial panel data.

Thanks to the referee. The references mentioned above are cited in the revised manuscript. Please check it.

 

4. Please include paragraph the need for future research in the discussion session.

We appreciate this valuable advice for revising and improving our paper. The need for future research of this study is discussed at the end of the Discussion section, including liquefaction behaviors of the post-cyclic saturated loess, and the dynamic properties of the post-cyclic saturated loess under coupling effect of aftershock and rainfall. Besides, a 3-D model of the structural characteristics of the post-cyclic saturated loess may help us have a better understanding of the mechanism. Please check it.

 

5. Please provide at least two cites where test instruments are used for similar study.

Thanks for your comment. We provided 4 references that the instruments are used for dynamic behaviors of the loess and the SEM tests of the loess, including references [3], [12], [25] and [30]. Please check it.

 

6. Seismic activity/ Earth quake occurred couple of decades back before this study was undertaken. Was there any further natural activity such as weathering, natural water table in the area which can have impact on Soil structure /the area of study. Authors are requested to provide assumptions, limitation of study.

Thanks to the referee. The impact factors on the structure of the loess are mentioned in the Introduction section, and the assumptions and the limitation of this study are provided. The revised manuscript is as follow:

The natural loess has a sub-stable structure with overhead pores, which is easy to damage under rainfall, seismic action and human activities such as agricultural irrigation and slope excavation [6, 14, 15]. However, the co-seismic effect and post-seismic effect of strong earthquakes are one of the key causes of structural variations of the loess. After the earthquake, the damaged structure will be reconsolidated and become relatively stable under the effect of external forces [16].

Please check it.

 

7. Aim or objective of study to be stated which can be correlated with conclusion.

  Thanks to the referee. The aims of this study are added in the Conclusion section. The modification is highlighted in red. Please check it in the revised manuscript.

Many thanks to Reviewer 2 for your valuable comments.

Reviewer 3 Report

Dear Author `s`,

The MS as whole is interesting, such kind of research are necessary and important for academia and governmental sectors as well, however, there are bullets you have to keep it in account, the following are scientific point to be re-consider, however, the details and some correction and questions you can find them in the attached revised MS:

1. in page 18, there is a contradiction between Fig. a and b in your discussion, form SEM I see something different from your discussion, BE CAREFUL , make sure which one is showing the tight textural appearance and increasing the pore spaces, see the revised MS for more info.

3. In Fig. 1, the areas are necessary to take by premium google earth (free program, easily to use), where the reader can observe the geological structure (paleo-tectonic) on premium google map more easier since your study data dealing with mechanical properties of soil...

4. Fig. 2, must be re-arrange (see revised MS), I see a fault on the map, in your area, could you tell me which kind of fault do you have: Shallow or deep-rooted fault, this can be easy SOMETIME to show by premium google pro., both fault will for sure influence on your data.

5. some of abbreviation shall identify previously, when you meant it first time: ex, Gd, Ya..

My best

Comments for author File: Comments.pdf

Author Response

1. in page 18, there is a contradiction between Fig. a and b in your discussion, form SEM I see something different from your discussion, BE CAREFUL , make sure which one is showing the tight textural appearance and increasing the pore spaces, see the revised MS for more info..

Thanks for the referee’s valuable comments. I believe this comment is very important. In Figure 15 (a) and (b), the microstructure of the loess before and after pre-shock is loose, with many pores among the gains. However, the pores in Figure 15 (a) are mostly trellis pores around by several gains and aggregates, and the size of the pores in Figure 15 (b) are even smaller, and the distribution of the pores are more uniformly. The possible causes of the variation of the pores are the loosen and rearrangement of the particles, and the trellis pores are collapsed due to the pre-shock. Moreover, the most conspicuous change between Figure 15 (a) and Figure 15 (b) is a large number of pores connected into tiny cracks in Figure 15 (b), resulting from the loosening and rearrangement of the gains during vibration.

Actually, the illustration of these figures is not clear, which causes misunderstanding of the results. Thus, we modified the analysis of the SEM images shown in Figure 15 (a) and (b). Besides, we improved the images shown in Figure 15 for adding some labels on them and enlarged the photos to make sure it is clear. The improvement is shown in the revised manuscript, please check it.

 

2. In Fig. 1, the areas are necessary to take by premium google earth (free program, easily to use), where the reader can observe the geological structure (paleo-tectonic) on premium google map more easier since your study data dealing with mechanical properties of soil....

Thanks to the referee’s valuable comments and suggestions. The Figure 1 was modified based on your comments. The satellite imagery of the landslides is added. Besides, the landslide area and mudflow area of the two landslides are encircled in a red line. The location of the landslides is shown in Figure 2. We believe these modifications may help the readers better understand the disasters. Please check it in the revised manuscript.

 

3. Fig. 2, must be re-arrange (see revised MS), I see a fault on the map, in your area, could you tell me which kind of fault do you have: Shallow or deep-rooted fault, this can be easy SOMETIME to show by premium google pro., both fault will for sure influence on your data..

Thanks for the referee. We have revised Figure 2 based on your comments. Moreover, a short introduction of the Tongwei fault is provided in section 2.1. The fault is a buried deep-rooted fault, and also the seismogenic fault of the M 7.5 earthquake occurred in 1718. Please check it in the revised paper.

 

4. some of abbreviation shall identify previously, when you meant it first time: ex, Gd, Ya...

Thanks for the reviewer’s comments. We carefully re-read the whole article and identified the abbreviation in first time. Please check it in the revised manuscript.

 

5. other comments listed in the attachment.

Thanks to the referee’ hard work and useful comments. The grammar mistake, misuse of the words and unclear expression of the sentences are improved. The reference [5] is cited in the revised manuscript. These comments will improve the quality of our work and give a good understanding to the readers. Please check the revision in the revised manuscript.

Many thanks to Reviewer 3 for your valuable comments.

Round 2

Reviewer 1 Report

Thanks for your response! I believe that your answers and modifications are sufficient. 

Author Response

The authors would like to express our sincere gratitude again to Reviewer 1 for his hard work and helpful advice.

Reviewer 2 Report

Review comments in earlier review have been incorporated. Quality of Manuscript has been approved.

Authors have carried out, most of the revisions.

Grammar and spelling generally needs to be checked.

After above revisions, paper can be accepted for Publication.

Author Response

Thanks to the referee's comments. The followings are the responses to the comments.

The authors have carried out, most of the revisions.

Thanks for the reviewer’s valuable comments. We have considered your previous comments 1, 4, 6, and 7 and conducted revisions in the Abstract, Introduction, Discussion, and Conclusion sections, which are highlighted in red in the Revised Manuscript. Please check it. 

Grammar and spelling generally need to be checked.

Thanks to the referee. We have read the manuscript again and checked the spelling and grammar mistakes. The revision is highlighted in red in the Revised Manuscript. Please check it again.

We are especially grateful for your hard work and helpful comments.

Reviewer 3 Report

Now, I believe the manuscript ready for publication..

 

Good luck

Author Response

Thanks to Reviewer 3's comment. We are especially grateful for your help to improve the manuscript.