Failure Assessment of Embankment Dam Elements: Case Study of the Pirot Reservoir System

Round 1

Reviewer 1 Report

The presented paper deals with the numerical analysis of the stability of selected structures on real dams. Weak (critical) points were appropriately selected and subsequently calculations for 3 scenarios were performed. The methods, procedure and results used are well described and presented.

I have a few questions and comments about the paper.

General concept comments:
A) In the introduction, I miss the references for similar articles.
B) In the discussion, I miss the comparison of results with similar analyzes on dams, or a comparison of models.
C) The main objectives of the article should be summarized at the end of the introduction/background chapter.
D) Does the dam have lower outlets (no mention)? Should not they also be verified as key structure elements?
E) It would not be possible to use the scenario for overflowing the crown of the dam (when reducing the spilway capacity (scenario 3) in combination with floods) - as correctly mentioned in the conclusions?
F) What is the accuracy of the created 3D terrain model?
G) It is a pity that at least the main parameters that appear in Table 1 have not been measured.

Specific comments:
1) On page 2, in line 66, the unit "MMS" is mentioned for the first time, but it is not explained.
2) What does "T" mean in Equation 4?
3) What does "FS" and "ε" mean in Equation 6?
4) The information in lines 178 and 183 is already mentioned in the paragraph above.
5) In Figure 2, there are numerical references in the circles that are not explained.
6) Line 231: What does "week points" mean? (weak points)?
7) Define the individual regions for figure 5.
8) The information in lines 306-308 is already mentioned in the introduction.
9) I lack an explanation (color legend) for picture 11.
10) Please, what are the units in Figures 9,10,13,14,15,16 (these are always without dimensional values and percentage values)?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

The paper presents an interesting case of study associated with an innovative criterium to assess the factor of safety of structural elements. Overall, the paper has a lot of potential. However, the main drawback is that the conducted analysis are not well presented, to the reviewer’s opinion. The reader, at least the reviewer, is lost and the objectives could be made clearer.

In addition to the general comment above, the authors can find below major, minor comments as well as typos.

Major comments:

The reviewer does not find the introduction very clear. The case study should only be briefly presented in this section: the main description is done in Section 3. Please avoid duplicated information. In his opinion, the introduction should show the state-of-the-art of the literature about a scientific problem (here, dam stability), and at the end highlight what’s lacking (even if it’s “only” application of existing methods to a case of study) to then introduce the rest of the paper. The reviewer was lost in this part. However, the description of the outline of the paper is appropriate, though it could be done in a separated paragraph.

Lines 188-191 is not really clear: Does it mean that only one material was used in the dam. As far as the reviewer knows, dam are built with an alternance of permeable and impermeable layers to be efficient. If the authors used only one homogeneous material, the reviewer thinks that the model loses a lot of accuracy.

Table 1 material should be present in one view of the dam for better understanding of the model. In addition, paragraph 265-271 does not help to understand where specific values are modified. The reference to Figure 5 is not clear.

Minor comments:

Line 91-94 seems a bit redundant to the reviewer. Can the author condense them?

Is the description at the beginning of section 2.2 relevant? It seems that the authors do not use them afterwards. If they want to re-start from the beginnin, the authors can then explain what is epsilon, Fs, Ssigma (even if trivial). The reviewer thinks it’s better to use lines to explain what “f” is and his relation with J2d. THe link could then be easier with Equation 10 and 151.

Line 131: Is the case where the numerical model converges while the displacement at certain locations of the model being too large (not admissible in reality) addressed/studied in the paper? The reviewer thinks it’s important to remind it somewhere

Line 214 – 216: Though the boundary conditions are taken far enough, they should be explicitly specified. One should also quantify (and checked) that it doesnot influence the results.

Figure 5: legends should be presented in the figure as well. The location of the elements (grout curtain) represented on Figure 5 should also be present in Figure 4, for reference. The reviewer does not understand to what it corresponds for now.

Line 279-280 seems in contradiction with line 269-270. Can the authors explain?

Figure 8: unless the reviewer makes a mistake: the “potential” is not defined before. Is it the potential from the Darcy law?

Some typos:

Line 113-115: the sentence misses a verb.

Line 221: detailed instead of detailed

Line 237: analiyisis

Line 296: loss instead of lose.

Line 340: dept

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

This paper presents a comprehensive numerical study on the failure assessment of embankment dam elements based on the case of the Pirot reservoir system. The manuscript is well written with a well-organized structure. There are some minor flaws in the current version. I recommend minor revision before publication.

1. The parameter names and units for all the color bars are missing. Please add.
2. A Discussion part is missing after the case study. You are expected to discuss the limitations and implications of this study.
3. The captions of Figures are too simply, which cannot guarantee the self-explanatory of figures.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Dear authors,

In general, the paper did improve and can now be considered for publication.

However, the schemes shown in the Figures could be clearer to understand where each material is and how the numerical model is distributed.

In addition to the general comments above, the authors can find a few minor comments below.

Minor comments:

In the introduction: the reviewer thinks that the words “facility” and “stability” are often (too much) used.

Line 223: the reviewer suggests adding a reference to Fig 2 corresponding material here (bedrock?), as: “rock mass (Bedrock in Figure 2) is homogeneous”. The reviewer is still lost here to understand what material corresponds to what.

Reviewer 3 Report

I am fine with the current version.