Comparative Analysis and Performance Evaluation of SSC, n-SAC, and Creep-SCLAY1S Soil Creep Models in Predicting Soil Settlement

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper mainly studies the performance of three soil creep models (SSC, n-SAC and Creep-SCLAY1S) in predicting soft soil settlement. The advantages and disadvantages of these models are compared and analyzed through laboratory tests and field data of Lilla Mellösa test embankment in Sweden. The results show that SSC, n-SAC and Creep-SCLAY1 S models perform well in predicting long-term settlement, but n-SAC and Creep-SCLAY1 S models have larger predicted horizontal displacement and higher sensitivity to parameters due to the introduction of anisotropy and deconstruction characteristics. The paper also discusses the limitations of the model in practical applications and proposes directions for future improvement. However, there are some problems in this paper, which can be modified and improved by the author.

1. The full-text formulas and pictures need to be displayed in the middle, so that the layout of the article is beautiful.
2. Some pictures are shown in Figure 1 and Figure 2. The whole picture and the label in the picture are blurred. It is necessary to optimize the full-text picture and re-insert it.
3. The secondary title in the text needs to be consistent with the text and the primary title font.
4. The experimental data used to compare the simulation ability of the model is relatively long. The experimental data measured in the early years are prone to large errors, which affects the prediction ability evaluation of the model proposed in this paper.
5. The table in this paper needs further beautification, such as font size and thickening, and the thickness of the lines in the table should be beautiful and consistent. For example, is the second horizontal line in the table the thickest?
6. In Figure 6, Mpa needs to be written correctly, and Eref needs to be written in a unified standard.
7. Can the gray background of the schematic diagram of the finite element model be deleted or adjusted to a pure white background?
8. Why is there a lack of Calculated 1977 data in Figure 14?
9. Why is there a lack of calculated 1977 data in Figure 14-16? Does this not affect the result analysis and the final conclusion?
10. Each legend in Figure 20 should be neatly arranged to facilitate scholars to read. In addition, why is there a lack of data for n-SAC Simulation-2.5 depth? And the lack of ' depth ' after the Creep-SCLAY1S-0m tag'
11. The model simulation results in this paper are mainly based on the comparison and analysis of the prediction results of settlement and pore water pressure, and lack of in-depth analysis of other important performance indicators such as stress-strain relationship.
12. Some references are old and fail to fully reflect the latest research trends in the field of soil mechanics. It is recommended to update some of the old literature and quote the latest research results in recent years.
13. The research is only based on the Lilla Mellösa test embankment in Sweden, without considering the influence of the difference of soft soil characteristics in different regions on the performance of the model. The research scope is narrow, and the universality of the conclusion is limited.
14. The model parameters mentioned in the paper are determined based on field investigation and laboratory results, but the specific methods and assumptions for parameter determination are not described in detail. There is a lack of discussion on the universality of the parameters under different soil types and geological conditions.

Author Response

All the author response is as in the attached file and revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the submitted manuscript, the authors attempted to compare advanced numerical models for the mechanical description of soft soil behaviour. The manuscript requires numerous corrections and responses to several questions. Below, I have listed the most critical problems, deficiencies, and comments that require elaboration.

Line 50, 126: Grimstad & Digago [2] -> correct the second author of the cited work (Degago!)

57-59 lines: "The time-dependent function of the stress-strain relationship, commonly referred to as secondary compression and widely recognized as creep deformation is also described in term of plastic resistance to compression, time resistance, viscosity, and strain rate effects [4],[5],[6]." need elaboration -> creep is not the same as secondary consolidation see for instance: Bjerre J., 2015 - Development and Evaluation of an Effective Stress Based Model for Soft Clays

Line 66: transpires _-> change the word  

Lines 81-84: There are no explanations for formulas (2) and (3).

Line 91: 1.1 "Soft Soil Creep Model" Explain the difference between the Garlanger model and the ABC Delft model developed by den Haan.

Line 100: There are no explanations for formula (5). Check through the entire manuscript and fill in the missing explanations of symbols used in equations.  

Line 109: Explain the difference between the Soft Soil Creep Model and the Creep-Sclay1s model. The description of the Creep-Sclay1s model is insufficient for readers unfamiliar with using advanced constitutive models. If you enter information about the "magnitude of the plastic multiplier in conjunction with the creep index", explain why it is essential. The descriptions of the models are not well thought out, and I think they should refer to the gist rather than just the information typically provided in the instructions for use of calculation programs, as seen in the PLAXIS manual. 

Line 109: Explain the term destructuration

128 Line: destruction or destructuration?

Line 137: What is the mobilization in K0, NC loading? 

Line 153: The subchapters should be numbered consecutively, or the text should be split into one chapter.
  
Line 167: Figure 2 should be redrawn in any graphics software, such as Corel. Figure 2 is blurry and fuzzy.

Line 170: Soil conditions: Instead of describing the ground conditions, include a geological profile. This text does not contribute anything to the article and is more suitable as a subsection for a master's or engineering thesis.

Lines 2010-215: "Subsequently, the fundamental characteristics, formulations, and parameters essential for the advanced soil models SSC, Creep-SCLAY1S, and n-SAC were meticulously examined. In the following phase, the methodologies utilized to determine critical soil parameters essential for these models, alongside standard testing procedures, were assessed. To evaluate the impact of parameters within the model, a comparative analysis among the models was conducted, accompanied by a detailed review of soil 215 test simulations." It would be helpful to explain how exactly the necessary parameters were determined, specifically whether they were chosen based on laboratory tests and then obtained through the optimisation method.

The information that the parameters were derived from two SGI reports is insufficient and does not provide precise details on how the model parameters were selected, particularly those for Creep-SCLAY1S and n-SAC. There is not much information on this topic in the geotechnical literature, so I suggest discussing this issue in a separate chapter. It is exciting to describe whether the Rate of rotation, the Rate of rotation by deviator strain, the Rate of destruction by deviator strain, and the Initial amount of bonding were calculated. I expect detailed explanations and discussions of this issue. In the reviewer's opinion, this will enrich the article and will be very valuable to readers.

Line 226: Establishment of Input Parameters
Table 1: use lower indices for kx/ky; ck 

Table 4: Why in the first label on the table, the symbols are tripled, for example: tmax, tmax, tmax?

The values of parameters are taken from the master's thesis of Gustafsson P., Rang T., 2011 - Numerical study of different creep soil models used for soft soils (see table 6.4, pp. 76) without proper reference. This raises questions about the author's actual contribution to the modelling and analysis. 

Line 261: What is "atop"? -> " a top"?

Line 270: Explain why the strain rate of 0.6% per hour is appropriate for the investigated soil. Is this choice ad hoc or based on previous lab investigations?

Line 276: Figure 5: Correct legend entry "evulated" -> Evaluated; divide the figure into parts a and b, and change the figure caption

Line 277: The CRS test simulations for 5 and 9 m also coincide with those carried out in the mentioned master's thesis. 

It should be explained why there are significant discrepancies around eps = 7% for the 5 m curve in the SSC and Creep-SCLAY1 simulations. A proper comparison is warranted, as the article's title suggests. Similarly, for 8 m, the models underestimate the yield stress. This should be discussed.

Line 284: "In conclusion, the CRS tests and simulations utilizing the established soil parameters through the selected models effectively captured the stress-strain trajectory in a reasonably accurate manner." This is an oversimplification; the author's contribution should be greater in the description and comparison of the influence of parameters on the soil behaviour. Why was no comparison made for other input parameters? How do other parameters affect the course of the curve, such as rs, ω, hardening parameter and other structure parameters? Sensitivity analysis is not sufficiently performed.

Line 350, 365: Figure 11 and Figure 12: The authors point out that "nonetheless, it is evident that n-SAC is proficient for long-term settlement assessments." However, comparing the curves in the figures, SSC more accurately reflects field measurements. Why? It is expected that a more refined model will better reflect the measurements. The problem is likely due to the inappropriate selection of parameters and the lack of proper optimisation, as well as the adoption of parameters from the literature rather than those derived from one's own analyses based on an appropriately designed research program. 

Line 357: "However, due to the lack of data for remolded samples, the slope of intrinsic compression line, λi* which is much lower than λ* could not be estimated properly." That is why the submitted work should fill these empty gaps. What is the real contribution of the authors?

Citations:

The institution is not the author listed with initials - this literature entry needs to be corrected.: Library, O.; Society, I.; Mechanics, S.; Engineering, G.; Committee, D. Problems of Soil Mechanics and Construction on Soft 525 Clays and Structurally Unstable Soils-Collapsible Expansive and Others. International Journal of Rock Mechanics and Mining 526 Sciences & Geomechanics Abstracts 1975, 12, A19–A20, doi:10.1016/0148-9062(75)92239-1.

Author Response

All the comments and suggestions made by the Reviewer #2 have been incorporated in the revised manuscript and the author response is as in the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, the authors applied Plaxis 2D to numerically simulate a common engineering problem. Overall, the manuscript is well written. Basically, I don't see technical problem from this manuscript. However, I have the following comments for the authors to clarify in the revision.

(1) I don't see the new scientific contributions from both numerical simulation and engineering application. I feel this is a numerical exercise of Plax2D model, although the authors based on a real engineering situation.I would suggest the authors to further clarify the new scientific contribution from either numerical simulation or engineering applications.

(2) The field dat was based on the information of soil profile in 1979. If it is possible, I would suggest the authors to use more recent data from the field.

(3) There are some difference between measurement and numerical prediction. I would suggest the authors further discuss the reasons.

(4) Limitation of the proposed work need to clearly stated.

(5) References are a bit too old. The authors can consider to cite some more recent references.

Author Response

All the comments and suggestions made by the Reviewer #3 have been incorporated in the revised manuscript and the author response is as in the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors did not avoid minor errors, which are indicated below. The authors should provide a detailed comment on the last remark.

Use the same equation editor for Eq. 4.

Lines 141-142 check the list of symbols and remove them from the main text

Lines 159-161 are identical to the above. Please be precise and list all symbols at the end of the manuscript to ensure uniformity.
Line 248, 270, 280 Karstumen et al. [38] -> Karstunen et al. [38]

Line 248, 270, 280 The list should be unified, and if there are two authors, the text should cite: Gustafsson and Tian [37]

GUSTAFSSON, P.Ä.R.; TIAN, T. Numerical Study of Different Creep Models Used for Soft Soils. 2011.

Line 283 remove text: Table 4. 

Line 463 rs parameter is not a rotational hardening parameter

Lines 361-362 These insights are elaborated in the supplemental section, where each model's behavioral response is explored through parametric variation. 

Authors should indicate where exactly the sensitivity analysis is located; there is no supplementary material included in the report or manuscript. Without it, the article is not suitable for publication. The reviewer would like to see the results of this analysis.

Author Response

Dear Reviewer:

Thanks for your great contribution to improving our manuscript. We have attempted to address all the below comments in the revised manuscript as follows.

1. Use the same equation editor for Eq. 4. >> we have changed the equation with the same editor.

2. Lines 141-142 check the list of symbols and remove them from the main text >> We checked the symbols and found no discrepancy. We have preferred to detail out the important symbols immediately after the equations as well as in the 'list of symbols.' This is because it will be quite difficult for the readers to refer to the list of symbols every time when they come across an equation while at the same time, the complete list of symbols will be a great reference to the readers while checking out the whole amount of symbols used in the paper. We hope you will take this decision positively. We thank you in advance.

3. Lines 159-161 are identical to the above. Please be precise and list all symbols at the end of the manuscript to ensure uniformity. >> The same as above!

4. Line 248, 270, 280 Karstumen et al. [38] -> Karstunen et al. [38] >> We have appropriately revised this citation wherever necessary. Thank you.

5. Line 248, 270, 280 The list should be unified, and if there are two authors, the text should cite: Gustafsson and Tian [37] >> Appropriately changed/revised. Thank you.

GUSTAFSSON, P.Ä.R.; TIAN, T. Numerical Study of Different Creep Models Used for Soft Soils. 2011.

6. Line 283 remove text: Table 4. >> There was some discrepancy. we have put Table 3 and Table 4 in sequence so that the citation of the two tables can be made in the same statement. We hope it addresses the concern.

7. Line 463 rs parameter is not a rotational hardening parameter >> this has been changed appropriately. It was a mistake. Thank you.

8. Lines 361-362 These insights are elaborated in the supplemental section, where each model's behavioral response is explored through parametric variation. >> In fact, we forgot to upload the supplementary material (file) while uploading the revised manuscript. It was a blunder from our side. We apologize. The supplementary material has been uploaded this time. Thanks very much!

9. Authors should indicate where exactly the sensitivity analysis is located; there is no supplementary material included in the report or manuscript. Without it, the article is not suitable for publication. The reviewer would like to see the results of this analysis. >> As in the above statement. Thanks very much.

We really appreciate your detailed check and an eagle's eye on the manuscript. Thanks very much.