Effect of Solidified Depth on the Vertical Compressive Bearing Characteristics of the Soil Continuously Solidified Pile Group Foundation

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors investigated the effect of depth on the compressive strength of SCS pile foundations. In the reviewer's opinion, the paper is interesting, and the results can help future work in this regard. However, there are a couple of comments that need to be addressed before the paper can be considered for publication. Please see my comments below:
1- Please provide more information in the introduction of the paper to indicate the novelty and importance of this study. 

2- It is suggested that the introduction of the paper be strengthened by including the following new articles on the piles:

"Review of available systems and materials for splicing prestressed-precast concrete piles." In Structures, vol. 30, pp. 850-865. Elsevier, 2021.

3- Please improve the quality of the figures (eg., Figure 16)

4- Please provide units for all equations used in the study.

Comments on the Quality of English Language

There are several grammatical issues including mixing passive and active voice, improper capitalization, etc. A grammatical review is suggested to clean up all these issues. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors proposed a new type of group pile foundation called soil continuously solidified (SCS) group pile foundation that has soil continuously solidified between piles to meet ultra-high bearing capacity design requirements. An indoor half-model test was conducted to investigate the compressive bearing capacity, load transfer law, and damage pattern of the soil. The results show that the ultimate compressive bearing capacity of the SCS group pile foundation is 4-9 times higher than traditional group pile foundations. The obtained results by the authors also indicated that the bearing capacity is mainly shared by the continuously solidified part and the pile lateral frictional resistance. The high strain damage zone of the soil at the bottom of the continuously solidified foundation is in the shape of an "abacus bead" for the 2D-14D foundation and an "inverted bowl" for an 18D foundation.

 

My present score on this paper is 50/100 and the major concerns of the reviewer on this paper are listed in the following:

1. It is not entirely clear what original contributions the authors have made in this work. It would be helpful if the dimensions or characteristics of this investigation that make this paper original were explained more clearly.

 

2.     I noticed that there may be a lack of verification or comparison with other studies in this research. It would be beneficial for the authors to verify their calculations and findings with other works in the field. This can provide more credibility and confidence in the results.

 

3.     The paper suffers from both any formulations for the main factors (i.e., settlement and load-bearing capacity), as well as a solid verification of the obtained results to investigate the reliability of the obtained results from the experiments. 

 

4.     The solidified part mainly acts as a beam-like element, indicating that the flexural moment will be also transferred/produced at the connecting points with the piles. Therefore, it is expected that such a phenomenon leads to the reduction of the load-bearing capacity.  

 

5.     The authors should recognize the importance of advanced techniques like deep learning and neural networks in solving engineering problems. These methods are highly effective and necessary for dealing with complex issues, especially considering the uncertainties that engineers often encounter in their work. To this end, the authors should display the following references in the present work to emphasize the significance of these methodologies and algorithms in analyzing the present problem:

- Wu, Z., et al. (2022). A comprehensive review on deep learning approaches in wind forecasting applications. 

- Benbouras MA, Petrişor AI, Zedira H, Ghelani L, Lefilef L. (2021). Forecasting the bearing capacity of the driven piles using advanced machine-learning techniques. 

- Gasparin, A., Lukovic, S., Alippi, C. (2022). Deep learning for time series forecasting: the electric load case. 

- Khan, J., Lee, E., Kim, K. (2022). A higher prediction accuracy–based alpha–beta filter algorithm using the feedforward artificial neural network. 

 

6.     The main privilege of using the solidified part in the pile group is the reduction of the settlement and increase in the load-bearing capacity; however, the drawbacks of exploiting the solidified part should be also explained to have a better picture of all possible merits and drawbacks in one frame. 

 

7.     All the given factors and parameters in the manuscript of the paper should be typed in an italic manner. As it is seen, for example, in Equation (3), the presented factors have been typed using the “normal” font type, and thereby it should be suitably revised. 

 

8.     As an engineering professional, it is crucial to acknowledge the significant impact of artificial intelligence algorithms and artificial neural networks in various applications, particularly in designing of pile foundations and related problems. These advanced methodologies have been extensively utilized in numerical modeling and predicting interest fields, making them indispensable in the field of engineering. In future research, it may be beneficial to expand on this issue and reference related papers to provide a more comprehensive understanding of the topic. In this regard, the following referenced works based on efficient artificial intelligence algorithms should be explained in the paper briefly: 

- Hsiao, I. H., & Chung, C. Y. (2022). AI-infused semantic model to enrich and expand programming question generation.

- Mohanty R, Suman S, Das SK. (2018). Prediction of vertical pile capacity of driven pile in cohesionless soil using artificial intelligence techniques. 

- Deng, Y., Zeng, Z., Jha, K., & Huang, D. (2021). Problem-based cybersecurity lab with knowledge graph as guidance.

- Jia, Z., Wang, W., Zhang, J., & Li, H. (2022). Contact high-temperature strain automatic calibration and precision compensation research.

 

9.     How the location of the solidified part (effective or average depth of this part) and the pile spacing can influence the load-bearing capacity of the pile group? Please explain in detail. 

 

10.  Can the authors propose an optimal design of the solidified part, including its dimensions and depth, leading to the maximum load-bearing capacity of the pile group? How do the pile diameter, pile depth, and inter-pile distance (free spacing) as the crucial geometrical factors of the structure influence this optimal design? Please clarify in some detail. 

 

11.  Some grammar and style errors exist that should be paid attention to by the authors:

11.1. Line 108, “Sun Tao et al.[32]” must be changed to “Sun et al. [32]”.

11.2. In most cited references, there should be a free spacing between the last letter of the preceding word and the first bracket associated with the reference number. Therefore, in line 131, the statement “this test.[32]” must be modified to “this test [32].”.

11.3. Line 125, “Figure 3. Relation between drop distance and relative density” must be modified to “Figure 3. Relation between the drop distance and the relative density”. 

11.4. Line 167, “Figure 5. Design of test scheme” must be changed to “Figure 5. Design of the test scheme”. 

11.5. Concerning the x-label and y-label of Figures 6 and 7, the statements “Load /N” and “Settlement /mm” must be modified to “Load (N)” and “Settlement (mm)”, respectively. 

11.6. Based on the above comment, all units should be provided inside parentheses instead of after the backslash and other formats. 

11.7. Line 193, “fitting method[35-38]” must be modified to “fitting method [35-38]” (free spacing between the word “method” and the first bracket should be considered). 

 

The whole paper should be rechecked carefully, and every grammatical and style error must be removed accordingly. 

 

12.  The authors' suggestions for future works are invaluable. The next step and advancement should be carefully considered. It is recommended that the last paragraph of the "Conclusions" section be devoted to this matter, as it can benefit a wide range of people, including interested readers, followers, and other scholars.

 

After receiving the revised version and the authors’ responses to the above major queries, I will review them and put my possible complementary comments. For this purpose, the authors are highly advised to answer all the raised issues fully and methodically, showing me that the revised version is much better than the present version from both grammatical and technical points of view. If all the revisions to the paper and the answers to the above questions are provided reasonably, I can recommend it for possible publication in Applied Sciences. 

 

Comments on the Quality of English Language

Some grammar and style errors exist that should be paid attention to by the authors:

11.1. Line 108, “Sun Tao et al.[32]” must be changed to “Sun et al. [32]”.

11.2. In most cited references, there should be a free spacing between the last letter of the preceding word and the first bracket associated with the reference number. Therefore, in line 131, the statement “this test.[32]” must be modified to “this test [32].”.

11.3. Line 125, “Figure 3. Relation between drop distance and relative density” must be modified to “Figure 3. Relation between the drop distance and the relative density”. 

11.4. Line 167, “Figure 5. Design of test scheme” must be changed to “Figure 5. Design of the test scheme”. 

11.5. Concerning the x-label and y-label of Figures 6 and 7, the statements “Load /N” and “Settlement /mm” must be modified to “Load (N)” and “Settlement (mm)”, respectively. 

11.6. Based on the above comment, all units should be provided inside parentheses instead of after the backslash and other formats. 

11.7. Line 193, “fitting method[35-38]” must be modified to “fitting method [35-38]” (free spacing between the word “method” and the first bracket should be considered). 

 The whole paper should be rechecked carefully, and every grammatical and style error must be removed accordingly.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The paper presents the experimental model and the tests on a deep foundation of two piles bonded by a continuous solid layer at different depths.

The authors studied the behaviour and the bearing capacities of this foundation under vertical loads.

From the experimental program point of view, the research is interesting and the results are useful, but some comments need to be done.

 

- the physical model of the foundation is made totally from aluminium alloy. Regarding the piles that is usually done in physical modelling, but my comments are related to the continuous solid layer which connected the piles. In fact, this layer represents a soil layer which was improved by some technique (jetgrouting for example). Or even improved, a soil layer cannot attend the mechanical characteristic of the pile’s material (steel or concrete). Therefore, there must be an important difference in rigidities between the piles and the continuous soil layer. Additionally, in the experimental model, the piles and the solid layer are connected by a structural adhesive which probably prevents any possible sliding between the piles and the solid layer. In these conditions an analysis in friction in the contact zone of these two pieces is meaningless.

- the use of a half-model is interesting for the possibility of view of the behaviour of the soil layers along the piles (to establish the deformations at the maximum load and approximate the failure mode). But this cut in a half of the model and the positioning near the glass of the container surely affect the results and this aspect is not treated by the authors. Related to this aspect of the physical model it would have been interesting to see some photos of the experimental model trough the container glass wall.

- Therefore, considering the above comments, I think that the results obtained by the authors are qualitative rather than quantitative and the authors must discuss this aspect. It is risky to consider that the quantitative results obtained through the experimental model can be extrapolated to a real case.

 

Apart from these comments, some interventions are needed on the text of the paper:

- there are many paragraphs which are not clear and needs to be improved (ex: rows 21-23; 46-49, 122-123, 159-160, 274-275 – notations missing, row329);

- chapters 3.1 and 3.2 have the same title;

- the numbers of the chapters 4.1 – 4.4 are wrong;

- the titles of the figure 16 are wrong;

- the conclusions need to be reformulated taking into account my comments above.

 

In my opinion, the conclusion (1) needs more analysis. The position of the solid layer is rather related from the length of the piles than the diameters of the piles. From the analysis of the load transfer figures it is obvious that the solid layer action like a bearing layer and the transfer under it is minimal. So the positioning at the bottom of the foundation is probably better for any diameter of the piles. If the authors are not agreeing with this comment, at list they have to argue their conclusion.

 

Conclusions (2) and (3) needs to be reformulated considering the comments related to de deficiencies of the experimental model.

 

The terms “abacus bead” and “inverted bowl” are quite unusual. Maybe the authors could find some other terms.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for addressing the queries raised by the reviewer in previous versions. I have carefully reviewed the current version of this paper and I must say that it has improved significantly in terms of both the quality of the language and the technical aspects. Based on this, I highly recommend this paper for publication in Applied Sciences.

Reviewer 3 Report

Comments and Suggestions for Authors

authors responded to comments