Photogrammetric Prediction of Rock Fracture Properties and Validation with Metric Shear Tests

Round 1

Reviewer 1 Report

First of all, the manuscript did not follow the editing instructions (e.g.: In the text, reference numbers should be placed in square brackets [ ] and placed before the punctuation; for example [1] - in this version, the name(date) system was used)

Please delete Line 22-23

I suggest an additional chapter: List of symbols (e.g. the JRC in Line 142 is not understandable)

Fig 14: replace y and x symbols with shear strength normal stress symbols, respectively. 

 

Author Response

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Reviewer 2 Report

The researchers have dealt with this topic for more than 40 years. Shortcomings associated with estimation of JRC is very well reported in the literature. Both Z₂ and Z₂^’ are measures of only the slope of a roughness surface. In addition to a measure of slope, a measure of amplitude of roughness is needed for proper and complete quantification of roughness. Several roughness parameters are available in the literature which incorporates both the slope and amplitude of roughness. Surprisingly, this manuscript has not cited any of those parameters in the text and the reference list. Therefore, the authors are advised to perform a proper literature search and review on the topic dealt with. Another major drawback of both Z₂ and Z₂^’ is both parameters provide infinite many values depending on the used sampling interval. In another words, no unique value exists. In the literature some roughness parameters are available which have less influence of sampling interval. Again, this manuscript has failed to cite those references.

The literature is full of controversial findings on scale effects of roughness and joint peak shear strength. The authors have found no scale effect on residual strength of joints. However, they have found negative scale effect on peak shear strength of joints. They have not explained the reason for this. The reason for that is the roughness heterogeneity effect. In the literature the researchers who reported either the negative or positive scale effects have not investigated the effect of roughness heterogeneity on scale effect. Therefore, they have reported misleading negative and positive scale effect. If the joint surface is relatively homogeneous there should not be any scale effect. As the extreme situation, 100% smooth joint has no scale effect. All these information is available in the rock mechanics literature.

In summary, this manuscript has nothing new compared to what exist in the rock mechanics/engineering geology literature. The literature is far more advanced than the material given in this manuscript. The manuscript has failed to provide a proper literature review. This manuscript also has provided some misleading information on scale effects. Due to the above reasons, this manuscript is recommended for rejection.

Comments for author File: Comments.docx

Author Response

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Reviewer 3 Report

This paper presents the study on the laboratory determination of the shear strength of rock joints for large samples. Three different normal stress levels of 3.6, 6.0, and 8.5 kPa were conducted with two granite samples with artificially generated fractures. The roughness of the surfaces was measured using a profilometer and photogrammetry. The scale-corrected profilometer-based method and the photogrammetry-based method were adopted.  

After reviewing this manuscript, the scientific findings from the analysis may be significant. It is an interesting paper; however, it is suggested that the article in present form is recommended for the consideration of the acceptance in the journal of Geosciences if the following comments are applied.

1. It is suggested that the authors should emphasis main findings or the significance of the results in the abstract. Besides, there are typos in line 21 to 23 which need to be removed.
2. The authors mentioned push shear tests. The ISRM suggested method for laboratory determination of the shear strength of rock joints is named the direct shear strength tests of rock discontinuities. The authors should clarify the differences of the push shear test and the direct shear strength test.
3. The use of the abbreviation in this article should be revised. For example, “the scale-corrected profilometer-based method (JRC)” and “the photogrammetry-based (Z’2) method” are misleading the readers. What is the meaning of the JRC and Z’2. The abbreviationis a shortened form of a word or phrase and should be appeared at the first time. If “JRC” in line 45 is the first appearance, the authors should list its full form of the word. The authors should carefully read the whole manuscript and revise the use of the abbreviation.
4. The title of the manuscript is too long and not appropriate. Shorter title is suggested.
5. In Figures 12 and 13, the scale of x-axis is not appropriate. The authors should clearly present the shear strength before the peak occurred. In these figures, the shear strength before the peak can not clearly presented.

Author Response

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Round 2

Reviewer 1 Report

n/a

Reviewer 2 Report

This reviewer rejected the original version after giving several reasons. The responses given for all the reviewer's comments are very poor. Therefore, this reviewer recommends rejection again with very high confidence.  

Reviewer 3 Report

Since the authors have revised the manuscript according to the reviewer's comments, I have no further comments. The manuscript is suggested to accept as it is.