Geomechanical Characterization of Unwelded Volcanic Bimrock Materials for Sustainable Slopes: Application to Road Instability Problems in the Western Cordillera of Ecuador

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper systematically proposes a five-step geomechanical characterization method for unwelded volcanic bimrock materials. And the method sets a reliable framework for geotechnically describing bimrocks materials, explaining the actual stability state of the slopes. However, the paper has the following shortcomings :

1. There are two periods in the title of the paper. It is recommended that the first period be changed to a colon.
2. The format of Table 1.is not standardized. It is recommended to modify Table 1.format according to Table 2..
3. The serial numbers of 4 Rock blocks characterization and 2.4.Matrix analyses were repeated. It is recommended to change the number before Matrix analyses to 2.5.
4. In the Introduction, it is recommended to make a brief comparative analysis with the existing bimrock-related research methods to highlight the uniqueness of this method.
5. The mesh selection of VBP calculation is mentioned in Section 2.3, but will different mesh sizes affect the VBP results ? It is suggested to supplement the relevant explanation.
6. It is suggested to supplement the flow chart of the key steps of the five-step geomechanical characterization method to make the idea clearer.
7. The example contains four slopes, but is the method universal ? It is suggested to supplement its practical discussion in practical engineering and clarify its limitations.
8. In the Matrix analyses, XRF and XRD results are mentioned, but will the composition of the matrix affect the mechanical properties ? Therefore, it is recommended to supplement the explanation.

Author Response

The authors would like to thank the contribution of the reviewer for their thorough examination of the manuscript and valuable comments, which will undoubtedly enhance the manuscript’s quality. The authors have tried to attend the comments and suggestions of the reviewer in this revised version of the manuscript. All the comments made by the reviewer are addressed individually. In each case, the reviewer’s comment/question is presented (in italic), and the authors’ reply/answer is given in the attached file.

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper employs a geomechanical characterization methodology for unwelded volcanic bimrock materials, overall I think the paper is well written and results are presented in a well-organized format. I have several following comments, please address them accordingly before the paper can be accepted:

1. Line 44, there is a typo “bimroks” should be “bimrocks”
2. Can you elaborate the image processing method used in section 2.3 VBP computing?
3. Can you also discuss how hydrogeological and seismic conditions can be incorporated into the future study?
4. Can you briefly summarize the geotechnical parameters of the selected slope? I wonder if there will be a distinguished difference between them.

Author Response

The authors would like to thank the contribution of the reviewer for their thorough examination of the manuscript and valuable comments, which will undoubtedly enhance the manuscript’s quality. The authors have tried to attend the comments and suggestions of the reviewer in this revised version of the manuscript. All the comments made by the reviewer are addressed individually. In each case, the reviewer’s comment/question is presented (in italic), and the authors’ reply/answer is given in the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Article does present a very interesting topic and an active area of research. therefore I would really tak pleasure in reading this article. However, this article require to revise quite much in order to meet the MDPI standards of publications.

There is a missing part of authors list, their affiliations.

please add a concluding paragraph to the introduction in order to connect the references to this article.

table 4 is very important, please use this table more in the article and connect it more closely with your collected data.

increase quality of the figure number 5 substantially

fix the refences ordering, 46 and 47 are presented after 50

increase quality of the figure number 7, this figure is not readable

There are many sections that they require re-writing. meanwhile there are some sections that are written very well. for example these two paragraph are very informative and written very well and I would like to ask the authors to revise their article quite heavily to have all paragraphs in their manuscript written like these paragraphs:

paragraph 1: Some studies conducted on bimrocks, both welded and unwelded [8-10,13,14,16,19], state that the mechanical behavior of these materials and their overall strength and stiffness depend mainly on the contrast in resistance between blocks of rock and matrix. Besides, some researches have tried to establish the strength parameters of a bimrock as a whole, following Mohr-Coulomb or Hoek-Brown failure criteria, from the individual values of strength parameters of the blocks of rock and the matrix, such as the matrix friction angle, the matrix cohesion and the rock blocks UCS [6,8,10,13,58,59]. Since those parameters are gathered when following the proposed geomechanical characterization, this maybe considered a first step for designing slopes on unwelded volcanic bimrock materials as well as designing stabilization measures at slopes where such materials are present.

Paragraph 2: This paper has presented a geomechanical characterization for unwelded volcanic bimrock materials, oriented towards their performance in terms of slope stability and landslide hazard occurrence. The characterization includes assessing both the geological and geotechnical features of unwelded volcanic bimrock deposits. It classifies the deposits into three types (debris avalanche, pyroclastic flow and lahar), analyzes the rock blocks and matrix geotechnical properties, as well as its composition, and define indices like the block size range and the VBP that characterize each slope. These aspects provide a reliable framework to estimate the expected behavior and its stability. It is also a first and fundamental step before addressing by common modeling tool the design of the slope and/or the stabilization measures needed.

Comments on the Quality of English Language

line 26: ... geological materials are a problem to be solved

line 31:  and are defined as mixtures of rocks of blocks with significant geotechnical properties within a finer-textured matrix.

line 36: the blocks of rock respect to the matrix that

line 39: blocks of rock respect to the matrix area

line 137: is set in terms of the scale of engineering interest for the problem under consideration, and related with a characteristic dimension

line 165: is not a bimrock, in mechanical terms, but a soil

line 175: other parameters to set can be the unit weight of the blocks and their weathering grade.

line 197:  a great content may generate pore overpressures during raining periods). 

line 273: The clasts did not move after fracturing and therefore are evidence of jigsaw crack structures (typical of avalanches).

line 287: Jigsaw cracks were observed

 

Author Response

The authors would like to thank the contribution of the reviewer for their thorough examination of the manuscript and valuable comments, which will undoubtedly enhance the manuscript’s quality. The authors have tried to attend the comments and suggestions of the reviewer in this revised version of the manuscript. All the comments made by the reviewer are addressed individually. In each case, the reviewer’s comment/question is presented (in italic), and the authors’ reply/answer is given in the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

My concerns has been answered. I agree to the publication of this paper.