Quasi-Prototype Size Testing of Wedge-Shaped Block for Armoring Embankment Dams and Levees

Round 1

Reviewer 1 Report (Previous Reviewer 1)

I appreciate the authors' many improvements in the revised article.  It was much easier to review with the page-formatting problem fixed from the first version.  Thank you!

I have made many editorial suggestions in the marked-up PDF file.  These are primarily to standardize the English and improve clarity.  There are only a few minor technical comments to be considered.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 1 Comments

Dear Sir / Madam:

On behalf of the rest of the coauthors, I want to thank you for all your recommendations and interesting comments and suggestions. We are convinced that the new version of the paper has greatly improved from the former one. We have changed the manuscript according to the minor edits included in your PDF file. Next, we are pleased to respond to the questions and comments you mentioned in your review:

Point 1: Pag.12: Can you say something about the accuracy of flow rate measurements and any calibration that was performed?

Response 1: Thank you for your question. According to the technical specifications of the sensor device incorporated in the NivuFlow Mobile 750 flowmeter, the uncertainty in the measurements (per scan layer) is < 1% of the measurement value (v>1 m/s) + 0.5% of the measurement value +5.5 mm/s (v<1 m/s). To verify the correct operation of the flow meter, the discharge values recorded by the flow meter were compared with those obtained by means of the stage discharge curve used by the exploitation services of the Bardenas Canal Irrigation Community for different openings of the canal intake gate. The result was completely satisfactory, according to the technicians of the Community.

Point 2: Pag. 12: Relative and absolute are not very meaningful or descriptive terms here by themselves.  I would suggest that red is relative to the chute, which could be called 'chute coordinates', while white is relative to true vertical.  This could be called 'absolute vertical coordinates' or maybe just 'earth coordinates'.

Response 2: We agree with your suggestion. The text has been modified as follows:

“Two coordinate systems (one relative to the chute and one absolute relative to true vertical) were used during the research work (Figure 16). The movements of the blocks were registered in the system relative to the chute.”

Were two coordinate systems necessary?  Was information gained from one system that could not be obtained from the other?  If not, maybe just report measurements in one system for simplicity.

Thank you for your question. Certainly, the movements of the blocks were recorded using the system relative to the chute. However, during the research, the true vertical system was used to design the facilities and to ensure an easier location of every part of the testing channel and instrumentation. Following your suggestion, we removed the coordinates of the targets in the absolute system in Table 2 to simplify the explanation.

Point 3: Pag. 15: There was apparently value in  water.  Perhaps explain why (just to satisfy reader's curiousity).

Response 3: Thank you for your suggestion. We decided not to include this explanation because it is not strictly necessary to understand the tests and in order not to be too long in the explanations and to be more synthetic. For your information, the chute is installed in a channel used for irrigation. Our goal of saving water was caused by the fact that the downstream reservoir was almost full and could be an outflow in the spillway. Furthermore, the discharges used in the additional input channel cannot be used to create hydroelectric power and are detrimental to the owners of the facility.

Point 4: Pag. 15: Had the gate been closed?  I don't think this was stated.

Response 4: Thanks again for your suggestion. We have changed the text to clarify this question as follows:

“The last discharge was the maximum possible inflow that could be supplied through the input control gate. Higher discharges required the closure of the gate to operate the overflow weir at the inlet. This operation lasted almost 1 hour, at which time the discharges were significant and the level in the Acequia de Sora increased.”

Point 5: 16: Are these displacements in the earth-vertical direction, or perpendicular to the chute slope?

Response 5: As explained in point 2, the displacements were measured perpendicular to the slope of the chute.

Point 6: Pag. 17: Has it been explained somewhere that rows are numbered beginning with #1 at the bottom of the chute?

Response 6: Thank you for your comment. This question has been clarified in Section 2.2. (just after Table 1) adapting the paragraph as follows:

“The WSBs were placed in horizontal rows, starting from the bottom row (row #1) and working upward. WSB placement used a staggered configuration of longitudinal joints among the blocks. To achieve the staggered pattern, half-pieces of WSB were placed at the end of alternate horizontal rows, as shown in Figure 11.”

Point 7: Figure 20a seems almost identical to Fig. 19.  Are both needed?

Response 7: We think so. Figure 20a shows the canal section (highlighted in the red box) that is detailed in Figure 20b.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Dear Authors,

The manuscript entitled "Performance of wedge-shaped block armoring for embankment dams and levees in a unique quasi-prototype size testing facility" carried out a series of tests of wedge-shaped blocks armoring was carried out in an experimental facility. The manuscript is well written, meeting the scope of the special issue, describing in detail the methodologies and results obtained. The study approach is relevant, mainly for use in spillways in multiple-use dams. However, I recommend some adjustments for manuscript enrichment, which are mentioned below:
-The manuscript needs to be revised in English, considering the tense, always using the verbs in the past tense, since the studies have already been carried out;
-Considering the apparatus: Hydraulic Experimentation Facility - Luis Ruano - HEFLR used to carry out the tests, it was just a tool to evaluate the main objective of the study, which were the wedge-shaped blocks (WSB) and their respective dimensions. The evaluation of the HEFLR was not the objective of the study. Thus, the very detailed description of the HEFLR became unnecessary and exhaustive. Note that four pages containing five Figures were used, totaling eighteen photos. I recommend that the HEFLR could be summarized in just one Figure with photos of the main parts. The rest of the photos should have been in the Supplementary Materials.
-I refused to download the videos in Supplementary Materials, because I would spend around 30 minutes. Therefore, I recommend that authors reduce the compressed file size, or upload each file separately.
-Although the study carried out force measurements to extract the blocks, the authors must make it clear about their use, as shown in Table 3.

Considering the abundance of data and assessments, I ask:
-Would it be possible to consider the types of blocks (small, medium and large) and their respective weights and make correlations with Depth, Slope and Distance?
-Would it be possible to correlate the Total Energy (H = V2/2g + y + z) with the types of blocks and the Time? It is possible to do it using Survival Analysis, using Cox regression model (https://www.wiley.com/en-us/Applied+Survival+Analysis%3A+Regression+Modeling+of+Time+to+Event+Data%2C +2nd+Edition-p-9780471754992).
These are my doubts and suggestions that could enrich the manuscript. The authors should try to do or justify why it was not possible.

-The Conclusion must leave a clear message: What type of block and what are the respective dimensions of Depth, Slope and Distance along the spillway, which would be possible to use safely, that is, without the occurrence of the blocks being extracted by the chute .

I have made some comments and suggestions which are in text boxes in the attached file.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2 Comments

Dear sir/madam:

On behalf of the rest of the co-authors, I want to thank you for the fruitful comments that helped us to improve the quality of the paper. We are convinced that the new version of the paper has improved a lot from the former one. You can find the answers to the requested changes and comments about the manuscript in the following.:

Point 1: The manuscript needs to be revised in English, considering the tense, always using the verbs in the past tense, since the studies have already been carried out;

Response 1: Thank you for your kind comment. The time has been revised and all the actions carried out in the research work have been put in the past tense.

Point 2: Considering the apparatus: Hydraulic Experimentation Facility - Luis Ruano - HEFLR used to carry out the tests, it was just a tool to evaluate the main objective of the study, which were the wedge-shaped blocks (WSB) and their respective dimensions. The evaluation of the HEFLR was not the objective of the study. Thus, the very detailed description of the HEFLR became unnecessary and exhaustive. Note that four pages containing five Figures were used, totaling eighteen photos. I recommend that the HEFLR could be summarized in just one Figure with photos of the main parts. The rest of the photos should have been in the Supplementary Materials.

Response 2: Thank you for your comment. We agree that the description of an installation should usually be brief. However, in this case, the installation is considered highly relevant because it is unique due to its dimensions and supply flow, and this is the reason why so much emphasis has been placed on it. We do think the description of the non-conventional facility may be interesting for research groups that work in hydraulics and are planning to make experimental research on a prototype scale.

Point 3: I refused to download the videos in Supplementary Materials, because I would spend around 30 minutes. Therefore, I recommend that authors reduce the compressed file size, or upload each file separately.

Response 3: We are very sorry for the inconvenience caused. We just followed the instructions in the journal to upload Supplementary Materials.

Point 4: Although the study carried out force measurements to extract the blocks, the authors must make it clear about their use, as shown in Table 3.

Response 4: Thank you for your suggestion. The aim of this section of the article is just to provide information about the force needed to extract the blocks in dry conditions. The reason is that one of the mechanisms that could lead to the failure of the armoring is the uplift pressures at the base of the blocks during operation when the overflowing is happening. Unfortunately, we could not make extraction tests in overflowing conditions but we think that the obtained results can give valuable feedback about the uplift forces needed to extract a block from the original position in the armoring.

Point 5: (Table 1) Why didn't the authors evaluate the slope (alpha and beta) and the resulting hydrostatic pressure?

Response 5: We are very sorry but, we are not sure about the meaning of this suggestion. Perhaps the confusion could be explained because there was an error with the symbols. Actually, ‘a’ and ‘b’ are ‘α’ and ‘β’, which are represented in the lateral view of Figure 10.

Point 6: Would it be possible to consider the types of blocks (small, medium and large) and their respective weights and make correlations with Depth, Slope and Distance?

Would it be possible to correlate the Total Energy (H = V2/2g + y + z) with the types of blocks and the Time? It is possible to do it using Survival Analysis, using Cox regression model (https://www.wiley.com/en-us/Applied+Survival+Analysis%3A+Regression+Modeling+of+Time+to+Event+Data%2C +2nd+Edition-p-9780471754992).

The Conclusion must leave a clear message: What type of block and what are the respective dimensions of Depth, Slope and Distance along the spillway, which would be possible to use safely, that is, without the occurrence of the blocks being extracted by the chute.

Response 6: Thank you for your comments. Unfortunately, we could not measure drafts or dynamic pressures on the blocks as in previous laboratory work. In future research work, when new funding is available, it is planned to improve the facilities and carry out these measurements and be able to obtain the requested correlations, and carry out a statistical treatment of the results. We do think that, once we have these results, it will be possible to reach more precise conclusions about the blocks.

Point 7: What were the slope values (% or m/m) established? The authors must mention the slopes used for the tests.

Response 7: The slope used in the test performed for this article is indicated in Subsection 2.1, in the text just above Figure 6:

“The configuration selected for the tests was 2H:1V. The side walls of the chute are 2.50 m high, measured perpendicular to the bottom. The wall on the right side has clear methacrylate windows to allow observation during tests (Figure 6).”

Point 7: Include the map with the country, state and geographic coordinates.

Response 7: Following your suggestion, the geographic coordinates of the facility (42° 3'59.34" N, 1° 4'12.22" W) have been added to the title of Figure 1.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report (New Reviewer)

Dear Authors,

The authors answered most of my questions, and I confess that after the second review I could better understand the various tests that were performed. This was only possible due to improved descriptions in the text and watching the videos (I had no choice, I was forced to download them). However, I still consider that the manuscript still has many photographs of the prototype, which makes them redundant. Remembering that we must also consider the Supplementary Materials (the videos), which show the prototype clearly. Thus, I recommend that authors reduce the number of photos, which will make the manuscript less "polluted". Also, inserting the map of the country, the state next to Figure 1, will certainly enrich the manuscript.

Author Response

Response to Comments of Reviewer 2 (round 2)

Dear Sir / Madam:

On behalf of the rest of the coauthors, I want to thank you again for all your suggestions and comments. We have changed the manuscript according to your recommendations. Next, we are pleased to respond to the questions and comments you mentioned in your review on round 2:

Point 1: I recommend authors reduce the number of photos, which will make the manuscript less "polluted".

Response 1: Thank you for your suggestion. We agree with it. According to your suggestion, figures 7, 8 and 13 have been removed from the manuscript. In addition, Figures 5 and 6 have been unified into one single figure (new Figure 5), deleting 3 of the 6 photographs that composed such figures.

Point 2: Also, inserting the map of the country, the state next to Figure 1, will certainly enrich the manuscript.

Response 2: Thank you for your suggestion. A small map of Spain has been inserted in figure 1 with the approximate location of the facility.

Author Response File: Author Response.pdf

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

This is an interesting article about unique near full-scale tests of wedge-shaped block protection systems for overtopped embankments.  The introduction and background sections need extensive editing to condense the information and improve the readability.  The focus of the article seems split between the performance of the WSBs and the performance/design of the test facility itself.

The central part of the article was difficult to review due to major formatting problems in the PDF file, with multiple iterations of the same figures/photos appearing on repeated pages and obscuring some of the text.

I expected more information about the observed failure mode for the small blocks under hydraulic loading.  The measurements of pullout forces are interesting, but I wish the article would do more to relate those measurements to the likelihood for failure during flow events.

Comments for author File: Comments.pdf

Author Response

We thank the constructive comments on the manuscript. We have changed it according to comments included in the PDF file of the reviewer with the detailed edits as follows:

P.1. Lines 1-2. The title was changed following your suggestion from “Performance of wedge-shaped block armoring for embankment dams and levees in a singular testing facility at quasi-prototype size” to “Performance of wedge-shaped block armoring for embankment dams and levees in a unique quasi-prototype size testing facility”.

P1. Lines 16-24. The abstract was changed following your comments.

P1. Lines 30-40. We modified the text in an attempt to be simpler and more condensed according to your indications.

P2. Line 78. Figure 1 was changed after English proofreading of the text box containing ‘Approach Road‘.

P3. Lines 80-102. There was an issue with the change from the original MS Word format to PDF, and the article you received lost the correct template. Sorry about that. We have fixed this issue and deleted the less relevant information about the elevation of the invert following your recommendation.

P4. Line 112. The term 'alveolar slab' was not correct and changed to 'honeycomb slab'.

Finally, every suggestion of an edit to the PDF file was reviewed and changed in the manuscript. Thank you for your helpful suggestions.

Reviewer 2 Report

1.          Many figures are repeated (ex: Figures 4 to 6); please revise them.

2.          What are the meaning and locations of ‘a, ‘b’, and ‘α’ in table 1?

3.          Manny reference errors (ex: figure 17,18,19); please revise them.

4.          What are the meaning of LARGE B.1 and LARGE B.2?

5.          The legend in figure 19 should be revised. The significant digit is too much.

6.          Lack of legend in figures 20 and 21; please add them.

7.          Most of the paragraph contents do not have a description with figure No. Figures 24 and 25 do not have any axis. It is hard to read.

8.          The whole article (figures and contents) needs to be re-arrangement.

9.          The conclusion does not provide innovation or design suggestions with relative hydraulic conditions or sediment transport effects.

Author Response

Thank you for the fruitful comments that helped us to improve the quality of the paper. You can find the answers to the requested changes and comments about the manuscript in the following.

1. Many figures are repeated (ex: Figures 4 to 6); please revise them.

We are very sorry for this issue. There was an error with the transformation of the original MSWord version of the article (that was the version that we uploaded to the website of the journal) to the PDF file and the whole manuscript lost the original format. We fixed this issue, and now the manuscript is free from such errors.

2. What are the meaning and locations of ‘a, ‘b’, and ‘α’ in table 1?

Thank you for your comment. There was an error in the symbols. Actually, ‘a’ and ‘b’ are. ‘α’ and ‘β’, which are represented in the lateral view of Figure 10.

3. Manny reference errors (ex: figure 17,18,19); please revise them.

This error was caused by the issue described in bullet #1, and it has been solved. We apologize for that.

4. What are the meaning of LARGE B.1 and LARGE B.2?

Sorry, but we could not find these references in the text. Could you please let us know where the locations are at the manuscript?

5. The legend in figure 19 should be revised. The significant digit is too much.

Thank you for your suggestion. The figure has been modified with a new legend.

6. Lack of legend in figures 20 and 21; please add them.

Again, this error was caused by the issue described in bullet #1, and we solved it. Sorry for the inconvenience.

7. Most of the paragraph contents do not have a description with figure No. Figures 24 and 25 do not have any axis. It is hard to read.

Thank you for your comment. Figures 24 and 25 have been changed by adding axes for better understanding. We think the references of figures along the paragraphs have been fixed after the reformatting of the MSWord file.

8. The whole article (figures and contents) needs to be re-arrangement.

We totally agree with this comment. We made a new arrangement, and now the template should be correct.

9. The conclusion does not provide innovation or design suggestions with relative hydraulic conditions or sediment transport effects.

A unique quasi-prototype size testing facility was designed and constructed with the purpose of checking the behaviour of a new wedge-shaped block, with an enhanced air venting, under quasi-prototype conditions.  The design and construction of that unconventional testing facility was a challenge by itself, and allowed us to determine the resistance of the blocks of different sizes to high discharging flows, out of range in a hydraulic laboratory, the movements experienced by the blocks due to the water flow and the resistance of a single block of the armouring to extraction. These are original contributions.

However, one of the most relevant contributions was not highlighted enough in the conclusions. Therefore, we have added an additional line highlighting that rapid reduction of the water discharge, and consequently flow depth, is a potential failure mode of this type of protection. It was completely unexpected, it was never referenced previously in any research or state-of-the-art, and the occurrence of this type of failure could probably be observed because of the size and high flow discharge allowed by the facility.