A Study on the Load-Bearing Characteristics and Load Transfer Mechanism of Bag Grouting Pile in Soft Soil Areas

Round 1

Reviewer 1 Report

1. In the abstract do not use "we" but you must write in passive form

2. The abstract need more specific results like percenrages and num. Of the expe. Tests. 

3. The conclusion also need to improve with more details and num. Results and percentages for the copmarision. 

4. I sugges to make small paragraph about the application of such resesrch and tbe limitations

5. I think the paper need to compare with other studies with different

soft soil types. 

Author Response

1.In the abstract do not use "we" but you must write in passive form

 Reply1:I've changed the syntax to a passive statement in the abstract.

2.The abstract need more specific results like percenrages and num. Of the expe. Tests. 

Reply2:I have added a bearing capacity increase of 8.8% with a combination of design parameters.The optimal combination in this paper is a pile length of 18m, pile diameter of 0.4m, pile spacing of 1.0m, bedding thickness of 0.3m, and grouting pressure of 0.6MPa.

3. The conclusion also need to improve with more details and num. Results and percentages for the copmarision. 

Reply3:In conclusion,I have added a bearing capacity increase of 8.8% with a combination of design parameters.The optimal combination in this paper is a pile length of 18m, pile diameter of 0.4m, pile spacing of 1.0m, bedding thickness of 0.3m, and grouting pressure of 0.6MPa.

4.4. I sugges to make small paragraph about the application of such resesrch and tbe limitations

Reply4:Since the study context is a site in Ningbo, China, the loading values and design parameters involved in this test are carried out for this project and have been labeled yellow in Section 2.1.

5.

5. I think the paper need to compare with other studies with different soft soil types. 

Reply5:Because originally bag grouting piles were only widely used in soft soil areas along the coast of China, there is less background of bag grouting piles in previous studies, as described in the introduction of this paper. However, fewer field tests were carried out in previous studies, and the content of field monitoring was different from this paper. There are not many researches to carry out the field test of bag grouting piles, so the authors believe that this paper has some innovations regarding this part of the field test.

Supplement:
Because the application of bag grouting piles is not particularly widespread, fewer researches have been carried out at present, and it is also pointed out in the current national specification [14] that the research of bag grouting piles can refer to the research of cement mixing piles, high-pressure rotary spraying piles and other pile types. The paper lists the literature on bag grouting piles with good research results in recent years, and there are also some related literature on other pile types, which are also of some reference significance.

Reviewer 2 Report

In the present research article, the authors have studied the load-bearing characteristics and load-transfer mechanism of bag grouting piles in soft soil. The study is interesting and may be useful for the readers of the scientific society. Please find below comments which may help the authors to improve the quality of the manuscript.

1.     The initial few lines of the abstract are not written properly. Suggest improving.

2.     The clarity of Figure 3 should be improved.

3.     The picture showing site testing with instrumentation may be included in the article.

4.     The Mohr-Coulomb model soil model has been selected for numerical analysis. Suggest discussion.

5.     Was a sensitivity analysis performed to confirm that model convergence was achieved with the selected mesh size?

6.     How the mesh seeding has been performed? Details of flip bias ratio etc. to be added for clarity.

7.     What boundary conditions have been applied in the present numerical study?

8.     Section 4.3.1, as the load increases, the soil between the piles gradually transits from an elastic to a plastic state. How this transition is taken into account in computational software?

9.     How does the dilation of the soil affect the behavior of the present computational model?

10.  The conclusion part is not written well. Suggest improving.

11.  Reference to be checked properly.

 

 

 

The quality of English should be improved. 

Author Response

Thanks for your review!I have revised the article based on your reviews!

1.The initial few lines of the abstract are not written properly. Suggest improving.

Reply1:I have streamlined the abstract section, added some quantitative line conclusions, and have yellowed them.

2.  The clarity of Figure 3 should be improved.

Reply2:I have improved the clarity of Figure3.

3. The picture showing site testing with instrumentation may be included in the article.

Reply3:I have added the site testing with instrumentation an Figure5 shown.

4. The Mohr-Coulomb model soil model has been selected for numerical analysis. Suggest discussion.

Reply4:By citing similar literature, this pile type is mostly studied using the Mohr-Coulomb model with good accuracy.

5.     Was a sensitivity analysis performed to confirm that model convergence was achieved with the selected mesh size?

Reply5:The grid shape is  regular and after checking the grid, errors and warnings are 0. 

6.How the mesh seeding has been performed? Details of flip bias ratio etc. to be added for clarity.

Reply6:Global seed is set to 1, local encryption at the top and end of the pile and in the soil between piles is 0.25.

7.   What boundary conditions have been applied in the present numerical study?

Reply7:Set displacement constraints in X and Y directions (U1=0, U2=0) and fixed constraints at the bottom of the model (U1=U2=U3=0).And the method is similiar to the reference9.

8.Section 4.3.1, as the load increases, the soil between the piles gradually transits from an elastic to a plastic state. How this transition is taken into account in computational software?

Reply8:Because this paper takes and the reference is basically similar to the method, and after modeling, the calculation accuracy are high, the subsequent analysis and monitoring content is also relatively consistent, it is considered that the model adopts Mohr-Coulomb model as well as the modeling ideas for the project's loading simulation is reliable.

9.How does the dilation of the soil affect the behavior of the present computational model?

Reply9:The dilation was set to default

 10.The conclusion part is not written well. Suggest improving.

Reply10:Some quantitative elements have been added to the conclusions.

11.Reference to be checked properly.

Reply11:The authors checked the relevance of the references and added a piece of literature similar to the research in this paper as reference support. 

Reviewer 3 Report

Appreciate the authors for their effort taken in numerical modelling of the grout bag technology in the piling. Field data's can be collected on the increase in the volume of grout bag when it subjected to moisture. Pore-pressure dissipation of bag-pile foundation can be monitored and more over failure and types of failure of grout bag should be assessed. 

Author Response

Appreciate the authors for their effort taken in numerical modelling of the grout bag technology in the piling. Field data's can be collected on the increase in the volume of grout bag when it subjected to moisture. Pore-pressure dissipation of bag-pile foundation can be monitored and more over failure and types of failure of grout bag should be assessed. 

Reply:Thank you for your review on this article! Because of the limitations of the field test work at that time, the research work did some field static load tests, coring tests, compressive tests, and force transmission characteristic tests, and did not carry out some monitoring tests of pore water pressure. And when the author took over the project, the site does not have some experimental conditions, and does not support the development of destructive tests, only according to the information provided by the design institute to carry out a number of acceptance tests, follow-up research, the author will be based on your comments, when the conditions allow, to carry out additional experiments! The authors still tried their best to modify some of the matters to be improved and marked yellow. Thank you again for your review!