Research on Bearing Capacity of Secant Piled-Bucket Foundation in Saturated Clay

Round 1

Reviewer 1 Report

This paper has carried out theoretical, numerical simulation and experimental analysis on the bearing capacity of the new type of secant piled bucket foundation (SPBF). The research objective is clear and the research content is rich. The paper may be considered for acceptance after making minor revisions to the following issues.

1. In the second section, the paper makes assumptions about the SPBF foundation bearing mode of SPBF, and then conducts subsequent theoretical, numerical simulation, and experimental research, but each section and the final conclusion do not give a clear answer to this question. That is to say, after each section of the study, the questions and assumptions raised in Section 2 need to be answered based on the research results. Finally, in the abstract and conclusion, the comparative question is answered with hypotheses.

2. The full-text experiment does not specify the number of experiments in each group. Generally, multiple groups of experiments are required. In this case, it is recommended to use error bars, such as the form of a standard deviation.

3. Since concrete will eventually have different degrees of damage, can the DAMAGET and DAMAGEC of concrete in the ultimate state be extracted from ABAQUS to further illustrate the degree of damage?

4. Figure 4 (a) and (b) do not seem to be very different, whether it is considered to be placed in the same figure for presentation.

5. How do you get the k value in the formula 1 in section 2.1.2? And what are the k values in vertical loading test and horizontal-moment loading test?

6. In the analysis of Section 6, it needs to be supplemented in order to explain the stress of the foundation soil. In addition, it is also necessary to clarify the changes and requirements of the foundation inclination rate.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper, a novel secant piled bucket foundation (SPBF) is proposed for onshore wind projects to adapt to the large capacity wind turbines. Finite element analyses and the small-scale model tests of SPBF in saturated clay were studied. 

The paper can be accepted in the journal after making a minor revision :

1) please check some English words, such as "mement"

2) Boundary conditions are stated in sentences. It would be better to see these conditions either on geometry or in mathematical terms.

3) Deviations between FE results and small-scale test results are given as 10.65% and 10.25%. Aren't these deviations large a little bit ? How did you decide that the results of FE are good looking at these deviations. It is not clear.

4) Unit MN is written as an abbreviation. It would be better to see it in expanded form somewhere.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

This paper used experiments and finite element analyses to study the bearing capacity of the bucket foundation in saturated clay. The following problems need to be modified:

(1)   The test was a small model that should be 1/20 to 1/50 of the actual bucket foundation. Usually, a number of assumptions should be used to perform the small model test, such as the reason of scaling. The authors did not mention this part clearly.

(2)   The material of the bucket was not clearly mentioned. From Figure 6, it seems a concrete pile, but the elastic modulus of 200 GPa is the steel. The authors should mention this issue clearly.

(3)   The shear capacity of soil can be ignored the contact gap between the pile and soil. However, the horizontal contact between the pile and soil under cyclic loads, the gap should be important. It seems that this paper did not consider this issue. The authors should discuss this problem.

(4)   The yield criterion of the pile material (steel?) should be clearly mentioned. If it is steel, the von-Mises criterion should be used, but for the concrete material (reinforced concrete? Or pure concrete? It is not clear in this paper), the yield criterion is complicated. The authors should discuss this problem.

(5)   The contribution of this paper should be clearly mentioned, since the finite element analysis can only obtain the result of a certain pile but not the general condition of the bucket pile.

(6) English should be checked, for example: a number of ". And" should be changed to ", and".

   

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Dear authors,

The topic of your manuscript “Research on Bearing Capacity of Secant Piled Bucket Foundation in Saturated Clay” is interesting and relevant. However, I have several comments and questions,

1. The manuscript does not have the structure of a research paper. It has the format of a technical report and the reported findings do not create a strong connection with a scientific contribution or the novelty of the study. I recommend restructuring the manuscript into the traditional sections of a research paper: introduction, methods & materials, results, discussion and conclusion. There is material from each section disseminated in diverse sections on the current structure of the paper.

2. The novelty, scientific contribution, hypothesis, research questions or research objectives are not clear in the manuscript. Therefore, it is not possible to determine if the results prove/disprove the hypothesis and their connection with the novelty and scientific contribution. I strongly recommend to highlight in the last paragraph of the introduction the novelty, scientific contribution, hypothesis, research questions or research

3. The introduction needs to be significantly improved. It should include recent research on the research topic and develop a narrative that connects the scientific contribution with the research, highlighting the needs that the research is aiming to address.

4. Methods and materials are scattered through the manuscript and need to be integrated into a cohesive section that provides reader with the required elements to understand the research.

5. It is not clear why the test model presented in Figure 6 is useful for the research. Does not appear to have the right proportions for a wind turbine and its foundation. The proportion of the tower does not correspond with a commercial wind turbine. There is no rotor and therefore the model cannot be used for small scale testing or demonstration. Why is this test model presented and how does it contributes to the research?

6. The FE model developed in the research is unclear. What is the length of the tower considered for the application of forces? Which kind of winds were considered and how does this translate for load forces for the turbine. At what height if the forces being evaluated? It is important to consider that the most relevant forces will be applied to the rotor as it is impacted by wind. Which model is being considered? Is a uniform force evaluated or does it change through the rotor and through the tower?

7. Figures 11 and 13 should be improved. The Figure legends are too crowded, with excessive numerical values and labels. This needs to be improved and reformatted.

8. A discussion should be developed to connect the results with the proposed novelty, scientific contribution, hypothesis, research questions or research objectives. It should indicate how the hypothesis was proved or disproved and its implications of the scientific contribution of the research

9. The conclusion should be improved reflecting how the research provides new insights and advances wind industry.

10. I suggest that after the manuscript has been completed to be reviewed by an English native speaker. There are a significant number of grammatical constructions that can be improved.

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have answered my questions, and I have no other questions.

 

Reviewer 4 Report

Most of the review comments were addressed in this revised version of the manuscript.

I still suggest for the legends of figures  10, 12, 14, 15, 17, 18, 19, 20, 21 & 22 to be improved. The number format has too many digits, which makes the figure too crowded. The font size is too small (to accommodate so much information) making the legend difficult to read.