Numerical Investigation on the Spudcan Penetration into Sand Overlying Clay Considering the Strain Effects

Round 1

Reviewer 1 Report

The manuscript proposed a numerical model with Coupled Eulerian Lagrangian (CEL) approach for spudcan penetration into sand overlying clay. The effects of the critical state threshold in strain-softening model of sand and the clay sensitivity in strain-softening model of clay are investigated. The work is relatively interesting, and the structure and language of the manuscript are well prepared. Some comments below need to be addressed or considered to improve the technical depth of the manuscript.

1. In line 141, detailed reasons or references should be added to explain the great influence of roughness of spudcan on the shape and volume of plug.

2. Some writing errors should be checked, such as 015D in line 186.  

3. More experimental data should be added to verify the proposed numerical model.

4. Some certain limitations and scope of application of the method in this paper should be added into the conclusion part.

5. It is suggested that some recent research results of numerical model for spudcan penetration into sand overlying clay need to be added into the literature review.

6. Experimental data analysis and theoretical elaboration are too wordy and need further refinement.

Author Response

Dear Reviewer,

The authors are extremely grateful to you for providing your excellent comments and valuable advice in this paper. We have revised the paper based on your comments and corrected some minor errors in the English writing. The responses are listed in the attachment, which provide the comparison between the comments and the authors’ revision. We have pleasure in requesting you to review this paper again. Your prompt attention to this paper will be much appreciated.

Prof. Mingjie Li

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

Congratulations for the good work. It is an interesting article.

A few remarks:

I suggest you making the graphs a little bigger.

Line 195 Is it “0.02D” or “0.2D” the mesh size? Earlier, you specified 0.15D, 0.2D and 0.25D

Line 361 just check if is “;” or “.” at the end of reference 28

Author Response

Dear Reviewer,

 

The authors are extremely grateful to you for providing your excellent comments and valuable advice in this paper. We have revised the paper based on your comments and corrected some minor errors. Detailed responses are listed in the attachment, which provides the comparison between the comments and the authors’ revision. We have pleasure in requesting you to review this paper again. Your prompt attention to this paper will be much appreciated.

Prof. Mingjie Li

Author Response File: Author Response.docx

Reviewer 3 Report

Good afternoon,

The assessed work is interesting, carried out on the basis of a well-thought-out methodology, and above all, important for the subject of the discussed topic, which is the extraction of oil and gas at sea on the “jack-up” platforms up to 150 m deep. The stability and safety of this type of platform is obtained through the use of spudcan, the impact of which on the bottom, under preloading, can be destructive. The spudcan breaking the bottom or moving it could cause may induce structural damage, capsizal and even human casualty. Due to the wide range of influencing factors and limitations in the possibility of testing in "in situ" conditions, new methods, mainly numerical ones, are sought to help solve this exceptionally complex problem. Attempts to solve this problem by developing and proposing a numerical model that fully reflects the real market of cooperation between the platform and the seabed for a long time, as described by the authors in detail, but at the moment they are fully satisfactory. The authors proposed their own solution in the form of numerical model for spudcan penetration in sand over-lying clay, which can capture both the peak bearing resistance and the post-peak behavior. The CEL model implemented with a new constitutive model of sand, taking into accounts both the stress-dependence and strain softening, is proposed. The effect of the parameters in the constitutive models of sand and clay were investigated. A very important element of the study is the fact that the performance of the numerical model is validated against experimental data of centrifuge tests for different soil conditions e.g.: uniform sand, loose sand overlying clay, and dense sand overlying clay. The presented conclusions are specific and strictly related to the analyzes carried out.

The critical remarks:

-          unfortunately, the complicated way of characterizing the applied solutions means that the study may be difficult to read and understand for a potential reader,

-          I did not find any references to figures 2, 4, 10 in the content of the paper,

-          the legibility of descriptions of some drawings could be better, e.g. figures 6 or 7.

Summing up, I did not find any serious errors of a content-related nature in the work and I believe that the work may be published in the proposed periodical.

Regards,

Author Response

Dear Reviewer,

The authors are extremely grateful to you for providing your excellent comments and valuable advice in this paper. We have revised the paper based on your comments and corrected some minor errors in the English writing. Detailed answers are listed in the attachment, which provides the comparison between the comments and the authors’ revision. We have pleasure in requesting you to review this paper again. Your prompt attention to this paper will be much appreciated.

Prof. Mingjie Li

Author Response File: Author Response.docx

Reviewer 4 Report

The paper investigates an interesting topic, such as numerical investigations on the spudian penetration into sand overlaying clay. The methodology is correct. The structure of the paper needs some modifications before acceptance.

Introduction

Novelties need to be clearly expressed.

At the end, the structure of the paper needs to be described

Section2

How the void region can be representative of the whole problem?

This needs to be explained

Section 3

Figures of the various meshes are required

Section 4

4.1 please clarify this sentence: "and the strain (...) depth"

4.2 why the relative density 10% was assumed? Please explain.

4.3 this sentence needs to be demonstrated: "the numerical (...) very well"

The paper needs major revisions.

Author Response

Dear Reviewer,

The authors are extremely grateful to you for providing your excellent comments and valuable advice in this paper. We have revised the paper based on your comments and corrected some minor errors in the English writing. Detailed answers are listed in the attachment, which provides the comparison between the comments and the authors’ revision. We have pleasure in requesting you to review this paper again. Your prompt attention to this paper will be much appreciated.

Prof. Mingjie Li

Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

Figure 4 do not allow to understand correctly the 3D elements and boundary conditions.Please check.

Regarding boundary conditions (among penalty method, period boundaries, shear type), why did the authors chose simmetric? And not shear type? Please refer to

Castello F, Grasso S, Lentini V, Sannino MSV. Effects of Soil-Foundation-Interaction on the Seismic Response of a cooling tower by 3D-FEM analysis. Geosciences 2021 11,200

Elgamal A., Lu J., Yang Z. Liquefaction-induced settlement of shallow foundation and remediation: 3D numerical simulations. J. Earthq. Eng. 2005. 9 17-45.

Forcellini D (2016) 3D numerical simulations of Elastomeric Bearings for bridges, Innov. Infrastruct. Solut. 1:45

Lopez-Caballero F L, Farahmand-Razqui AM, Numerical simulation of liquefaction effects on seismic SSI, Soil Dyn. Earthq. Eng. 2008, 28 85-98

Mina D, Forcellini D, Soil-Structure Interaction Assessment on the 23 November 1980 Irpinia-Basilicata Earthquake, Geosciences 2020, 10 152

Other comments have been answered.

Author Response

Dear Reviewer,

Thanks again for your excellent comments and valuable advice in this paper. We have revised the paper based on your comments. The reason we use symmetric boundary condition is because the boundary effect in the present model is demonstrated to be negligible. And the symmetric bounday is effetive in this study. For detailed response, please refer to the attachment. We have pleasure in requesting you to review this paper again. Your prompt attention to this paper will be much appreciated.

Prof. Mingjie Li

Author Response File: Author Response.docx