Analysis of the Effect of Pore Water Pressure on a Small Radius Curve Section of a Fine Sand Layer under Cyclic Metro

Round 1

Reviewer 1 Report

Dear authors,

my comments have been added to the manuscript.

Comments for author File: Comments.pdf

Author Response

Dear reviewers,

        We are very grateful to your valuable suggestions and insightful comments for the manuscript water-2115347 entitled "Analysis of the effect of pore water pressure on a small radius curve section of a fine sand layer under cyclic metro ". According to your comments, we have amended the relevant parts in the revised manuscript. All the revisions have been highlighted with red colour in the revised manuscript. Please see the attachment for the specific reply.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors present an interesting study in train induced excess pore pressures and implications on the impact to a metro train tunnel.

Overall the premise of the paper is good and the general methodology is adequate.  However, there are serious gaps in the technical content of the paper that, in the current format, would exclude a recommendation for publication. The major issues are:

1. The soil characterization and properties are not explained within the paper.  How do the authors classify a soil as silty or sandy?  There are not index properties given to the materials.  This is problematic for supporting their conclusions and more importantly for the determination of the model input parameters.

2.  The model input parameters are not appropriate.  There are no testing, semi-empirical, or empirical means presented that would support the choosing of these values.  It is this component that drives the results and conclusions of this work and without an in-depth explanation or experimental results it renders the results and conclusions sections of the manuscript meaningless, as such I did not bother to review those in-depth as the model inputs were inadequate to start with.  This can be solved by the authors but not as is presented in the paper.

3.  The constitutive equations within the MIDAS software are not presented.  This poses two significant issues in the review process; (1) there isn't a way for the reviewer to evaluate if the correct constitutive equations are being applied; and (2) the numerical explanation reads as a "black box" where seemingly arbitrary values are entered and an output is obtained.

4.  Numerical models are typically constructed from one data set, validated by another, then applied to a problem.  This was not done in this case, based on what is presented in the manuscript.  If the model, as described by the authors, was calibrated by "inputting soil geomechanical parameters and applying train movement loads via MIDAS software" then a calibration wasn't exactly done but a tuning of a numerical model to get input/output match.  If this is done then there is nothing unique or novel in the numerical simulations other than to say that a finite element model was developed to show the same input parameters used to develop it.  If the authors were developing a new constitutive model and the goal was to evaluate it, then this is most definitely acceptable.  However, the authors simply entered some arbitrary discrete value fro a soil parameter into a commercial software and obtained an answer.

4. The numerical model(Fig 9) has a different topographic relief than the actual site (Fig 1).  Why is this? Figure 1 clearly shows that the soil layers vary in relief across the study area but the FEM is planar.  The simplification to a planer FEM geometry would require more in-depth analysis for determination of a suitable soil mechanical property than what is presented.

Overall, there is merit to this study provided that the major issues are addressed at a high level of detail.  Additional comments are provided in the attached file.

Comments for author File: Comments.pdf

Author Response

Dear reviewers,

We are very grateful to your valuable suggestions and insightful comments for the manuscript water-2115347 entitled "Analysis of the effect of pore water pressure on a small radius curve section of a fine sand layer under cyclic metro ". According to your comments, we have amended the relevant parts in the revised manuscript. All the revisions have been highlighted with blue colour in the revised manuscript. Please see the attachment for the specific reply.

Author Response File: Author Response.pdf

Reviewer 3 Report

The paper entitled "Analysis of the Effect of Pore Water Pressure on a Small Radius Curve Section of a Fine Sand Layer under Cyclic Metro" is a research on Long-term pore water monitoring also based on MIDAS finite element calculation platform.

- The paper can be published after some corrections.

- Page 1 (Introduction): Insert more details about liquefaction. For example considering the following paper:

-- Cavallaro A., Capilleri P. and Grasso S., (2018): "Site Characterization by in Situ and Laboratory Tests for Liquefaction Potential Evaluation during Emilia Romagna Earthquake"; Geosciences, Special Issue: "Site-Specific Seismic Hazard Analysis: New Perspectives, Open Issues and Challenges", Geosciences 2018, 8(7), 242, pp. 1 - 15. (ISSN: 2076-3263) DOI:10.3390/geosciences8070242.

- Page 2, Line 52: “Qui yang Lou et al.” is better “Quiyang et al.”.

- Page 2, Line 56: “Carlos E. Cary et al.” is better “Cary et al.”.

- Page 2:. For cyclic stress and triaxial tests considering the following paper:

-- Castelli F., Cavallaro A., Grasso S. and Lentini V., (2019): "Undrained Cyclic Laboratory Behaviour of Sandy Soils"; Geosciences, Special Issue: "New Perspectives in the Definition/Evaluation of Seismic Hazard through Analysis of the Environmental Effects Induced by Earthquakes", Geosciences 2019, 9, 512, pag. 1 - 27. (ISSN: 2076-3263) DOI: 10.3390/geosciences9120512.

- Page 2, Line 59: “Porcino D D.” is better “Porcino”.

- Page 2, Line 61: “Eyyub Karakan AlperSezer et al.” is better “Karakan et al.”.

- Page 2, Line 66: “Junhui Luo et al.” is better “Junhui et al.”.

- Page 2, Line 75: “Y-Q Tang” is better “Tang”.

- Page 2, Line 79: “Ge S. et al.” is probably “Shiping et al.”.

- Page 2, Line 81: “Wang Tao and Shi Bin et al.” is better “Wang et al.”.

- Page 2, Line 84: “Xu Yang et al.” is better “Xu et al.”.

- Page 2, Line 87: “Xiao Z R et al.” is better “Xiao et al.”.

- Page 2, Line 90: “Wei Hao et al.” is better “Wei et al.”.

- Page 5: It would be advisable to evaluate the variation of the pore pressure in correspondence with the transit of the train and the subsequent response time of the pressure gauges.

- Page 7, Line 204: “Figure 6” probably is “Figure 5”.

- Page 8, Figure 6: What is the difference between the Monitoring Points shown in Table 1 and those in Figure 6?

- Page 8, Figure 6: “2020. 11 - 2020. 55” probably is “2020. 11 - 2021. 55”.

- Page 10, Table 2: Insert a legend with the definition of the parameters shown. Is parameter m the same as Page 8, Line 240?

- Page 10, Table 2: Does the sequence of soil layers used represent the stratigraphic succession?

Author Response

Dear reviewers,

  We are very grateful to your valuable suggestions and insightful comments for the manuscript water-2115347 entitled "Analysis of the effect of pore water pressure on a small radius curve section of a fine sand layer under cyclic metro ". According to your comments, we have amended the relevant parts in the revised manuscript. All the revisions have been highlighted with green colour in the revised manuscript. Please see the attachment for the specific reply.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I appreciate the authors' revisions and response to the reviewer comments.

However, there are still some outstanding points from my first review that need to be addressed:

1.  The constitutive model equation needs to be presented.  There are numerous variations of Mohr-Coulomb (please correct spelling in the manuscript) models to capture different effects.  Please provide the exact numerical equation(s) used to solve the dynamic behavior to include the pore pressure generation model.

2. I appreciate the authors geological addition to the manuscript, however geological descriptions do not translate into discrete geotechnical mechanical properties.  For example see:

Taylor, O.-D.S., Abdollahi, M., & Vahedifard, F. 2022. Statistical Distributions of Near Surface Wave Velocities and Elastic Moduli in Unsaturated Soils. Soil Dynamics and Earthquake Engineering, 157 (2022) 107247.

The authors' use of discrete mechanical properties is problematic given the magnitude (mm) in the results/conclusions of this paper.  For example, if the Young's modulus is reduced or increased by 10% (which is quite reasonable for natural soil aleatory variability) does the model results differ than those presented?

I feel that if these two questions are explicitly addressed then the manuscript is suitable for publication after minor text editing.

Author Response

Dear reviewers,

        We are very grateful to your valuable suggestions and insightful comments for the manuscript water-2115347 entitled "Analysis of the effect of pore water pressure on a small radius curve section of a fine sand layer under cyclic metro ". According to your comments, we have amended the relevant parts in the revised manuscript. All the revisions have been highlighted with red colour in the revised manuscript. Please see the attachment for the specific reply.

Author Response File: Author Response.pdf