Experimental Study on Pile Load Transfer Considering Rice Stone Filled-In Gaps between Steel Drive Pipe and Pile Casing in Karst Region

Round 1

Reviewer 1 Report

The present article tries to investigate the influence of filling rice stones between steel drive pipe and pile casing on pile load transfer. Systematic laboratory tests have been conducted. The organization of the present article is reasonable. The following aspects should be addressed:

1: The novelty of the present article is suggested to be presented in Introduction. In addition, pay attention to the citation format of references.

2. Please check Figure 8 for the distance of the cave from the pile top, it does not match the description.

3. Please explain the three times of pipe pulling tests in the simplified model of plexiglass tube?

4. In Figure 17, the design loads 2.5kN at each stage, why does the image start at 10kN?

5. Please consider whether the statement in conclusion 4 is correct?

6. Some minor language errors should be addressed.

Author Response

Dear Editor:

Thanks for your letter and for reviewer’s comments concern our manuscript entitled “Experimental study on pile load transfer considering rice stones filled in gaps between steel drive pipe and pile casing in Karst Region”. Those comments are valuable and helpful for revising and improving our paper. We have studied all comments carefully and have made conscientious correction. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:

1. Proposed in the last paragraph of the introduction.
2. Modified image dimensions.
3. In the indoor simulation of the test pipe pulling process, the average value of three pulling analyses compared with the test was used to simulate the test pile shape to obtain its quality.
4. The load was intended to be 5kN at each level, Initial loading is twice that of 5kN, but it is discovered that the pile settlement is too great when the pile is loaded at the first stage. As a result, the test method is changed to 2.5kN at each stage.
5. Sand filling between steel casing and steel sheath increases the pile side friction resistance, improves the bearing capacity of the pile foundation, and ensures the verticality of the pile body.
6. Thank you for your suggestion. Some language errors have been corrected.

Reviewer 2 Report

The present article tries to investigate the characteristics of rice stones movement and load transfer when the casing is pulled out and the pile top is loaded. The rice stones are inserted between the steel drive pipe and the pile casing when the pile foundation crosses many cavities to guarantee the verticality of the pile foundation. Overall, the article is well organized and its presentation is good. However, some minor issues still need to be improved:

1. In Figure 4, please carefully check the position of the steel casing and indicate it in the picture.

2. Please explain that the organic glass tube model fully exerts the pile side frictional resistance when loaded to 25kN?

3. How to distinguish whether the model pile is unstable? Please explain

4. Suggest improving and explaining the significance and purpose of the two model settings, as well as why M2.5 cement mortar is used for the simplified model of organic glass tubes?

5. Please explain the difference in results between unilateral and bilateral karst caves.

6: Some minor language errors should be addressed.

 Minor editing of English language required

Author Response

Dear Editor:

Thanks for your letter and for reviewer’s comments concern our manuscript entitled “Experimental study on pile load transfer considering rice stones filled in gaps between steel drive pipe and pile casing in Karst Region”. Those comments are valuable and helpful for revising and improving our paper. We have studied all comments carefully and have made conscientious correction. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:

1. Thank you for your suggestion. The image has been modified.
2. The pile end started to bear the load when it was loaded to 25kN, from which it was inferred that the pile side friction force was fully exerted.
3. Pile instability occurs when there is significant deflection in the pile head and the pile cannot bearing load.
4. Thank you for your suggestion. Added relevant introduction in the article. The Plexiglas tube model does not consider the effect of soil around the pile and uses M2.5 cement mortar for pile end fixation.
5. Similar results for unilateral versus bilateral caves, the axial force of the pile body increases slightly on the upper side close to the cavity and barely changes on the lower side.
6. Thank you for your suggestion. Some language errors have been corrected.

Reviewer 3 Report

Comments:

1. Why did the test choose 30 and 40mm as the diameter of the Cave.

2. What is the deflection shown in fig.18, will the value increase when higher load applied?

3.What is the acceptable quantity of sand in karst cave in the tests, should be stated in the paper.

4.The paper only represent the pile test result. The paper is lack of suggestions for pile design and construction are added.

5.The conclusion should summerize the key features and advantage of the method with rice stone filled between piles and concrete, compared with normal methods.

Some literal error “pip” in Table 2&4 title. Similar error needs to be check.

Author Response

Dear Editor:

Thanks for your letter and for reviewer’s comments concern our manuscript entitled “Experimental study on pile load transfer considering rice stones filled in gaps between steel drive pipe and pile casing in Karst Region”. Those comments are valuable and helpful for revising and improving our paper. We have studied all comments carefully and have made conscientious correction. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:

1. Reference to the geometric proportions of cavities encountered during site construction. The choice of 30 and 40mm as the diameter of the Cave.
2. The article mainly considers the impact of filled rice stones on pile load transfer and does not consider the impact of deflections on the piles.
3. Thank you for your suggestion. It has been stated in the paper.
4. With the site construction as the engineering background, the article uses coarse sand instead of rice stone to study the effect of filling rice stone on pile load transfer.
5.  Thank you for your suggestion. Added in Conclusion 4.

Reviewer 4 Report

1. It is necessary to summarize the results of previous studies and their shortcomings in the introduction section in one paragraph, and the authors should state the innovation of their research compared to previous studies.

2. Put the reference numbers at the end of the sentences. for example:

Hong points out that in order to stabilize the inner casings, prevent the pile from deviating, and enhance the rigidity of the casings [10].

3. On what basis is the ratio of cement: river sand: water (1 : 6.29 : 1.48) selected?

4. No comments have been made regarding the scale of the model.

5. An image of the strain gauges on the model should be shown in the paper, and explanations should be provided about the calculation of the strain by the strain gauges in the manuscript.

6. In Figure 12, it is better to present the real picture of the experiment along with the schematic model.

7. The ultimate bearing capacity of the pile (the sum of the frictional and end bearing capacity) should also be evaluated and its results presented in Figure 16.

8. In Figure 1, it seems that the symbols for filled and semi-filled are not chosen correctly.

9. In Figure 2, in writing the description, the letters of some words are placed on the bottom line, which needs to be corrected.

10. In Figure 3, it seems that the number 8 represents cave 4. Please correct.

11. The way of writing the conclusion section should be modified. Only the research findings should be expressed with numbering.

12. The English language of the manuscript needs to be improved. Some of the grammatical errors and typos are mentioned below:

Lines 24 and 25: “While drive pipe is pull out”: While the drive pipe is pulled out

Line 37: “and filling in”: and fill in

Lines 52 and 55: “revealed that”: and revealed that

Please refer to comment 12.

Author Response

Dear Editor:

Thanks for your letter and for reviewer’s comments concern our manuscript entitled “Experimental study on pile load transfer considering rice stones filled in gaps between steel drive pipe and pile casing in Karst Region”. Those comments are valuable and helpful for revising and improving our paper. We have studied all comments carefully and have made conscientious correction. Revised portion are marked in red in the paper. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:

1. Thank you for your suggestion. Added in the introduction section
2. Thank you for your suggestion. The modifications have been completed as required.
3. Calculated according to the M2.5 cement mortar mix ratio.
4. Only considering geometric similarity ratio, without considering stress similarity ratio.
5. The strain gauge image on the model has been added, and explains the calculation of the strain by the strain gauges.
6. Due to the presence of cement mortar around the karst cave, the shape of the sand accumulation cannot be fully displayed. Therefore, indoor simulation of the pipe pulling process is used to calculate the quality of the karst cave sand.
7. The ultimate bearing capacity of the pile is shown in Table 6.
8. Thank you for your suggestion. Already labelled in Figure 1.
9. Thank you for your suggestion. Modifications have been completed.
10. The number 8 represents cave 4. The correction has been completed in Figure 3.
11. The conclusion section has been modified.
12.  Modifications have been made to English grammar issues.

Round 2

Reviewer 4 Report

The authors responded to all the comments from my previous review.

Author Response

Thank you for your suggestion. I have completed all modifications to the article.