Laboratory Study of Effective Stress Coefficient for Saturated Claystone

Round 1

Reviewer 1 Report

Dear Authors,

You've done some interesting work, but there are a few remarks you might want to take in account:

1.You attribute the relevance of your research to the problem of radioactive waste disposal. But why exactly the claystone? In the world, different rocks are used for this, such as  salts, granites, clays, tuffs... (see, for example, A. Hedin and O. Olsson, “Crystalline rock as a repository for Swedish spent nuclear fuel”, Elements12, 247 (2016);  D. Mallants, et al. “Performance assessment of the disposal of vitrified high-levelwaste in a clay layer”, J. Nucl. Mat. 298, 125 (2001); V. Tatarinov, et al. “An underground research laboratory: New opportunities in the study of the stress-strain state and dynamics of rock mass destruction”, Russian Journal of Earth Sciences 19(2):1-13 (2019), DOI: 10.2205/2019ES000659).
 Perhaps it was worthwhile to shed light on this issue in more detail and show why the study of the claystone is so important.

2.In the introduction, the authors simply list the results of other scientists. However, this section is intended to provide an analytical overview from which the research objective emerges. Now this is not felt.

3.Related to the previous remark. Mention of the Skempton's coefficient only appears in sections 2 and 3, omitted from the introduction section.

4.The abstract is not specific. Maybe the authors should rework lines 20-22 a little, add something from the conclusions.

Author Response

Dear Reviewer

We have replied to your suggestions in detail in the attachment and made modifications in the paper. Thank you for your work.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper is an attempt to determine the effective stress factor for claystone by varying the confining pressure and water pressure. Although it is difficult to judge the adoption of the paper because the system of the testing machine and the method of measuring the water pressure are not described, the interpretation of the test results will be incorrect in the following points, which are considered problematic for the paper.

1) It is probably a testing machine that controls the lateral confining pressure and the pressure at the upper or lower ends (loading pressure + water pressure) separately. The problem is the measurement position of the water pressure, which is probably not inside the specimen but at one of the upper or lower end faces. In this case, the B value is high because the water pressure near the surface increases when the confining pressure is increased. The authors state that the results indicate that the specimen is saturated, but the actual degree of saturation is not known, as it takes time for the water pressure to propagate into the interior. Therefore, even if the water pressure is applied from above or below, it is not known what the pore water pressure is for the entire specimen. If this is the case, the discussion of the effective stress factor loses its meaning.

2) When the water pressure is increased, axial strain is observed, but isn't this strange? If the increase in water pressure is small in relation to the increase in confining pressure, the effective stress should increase and isotropic consolidation should occur, and if the opposite is the case, isotropic expansion should occur. The axial strain may be evidence that the water pressure at the top and bottom ends of the specimen has become the load and the water pressure in the centre of the specimen has not increased.

 

The reviewer considers that there is a major problem as shown in the above, but if the peer review is to continue, the reviewer would like the following points to be corrected.

1) Section 1: Define what claystone is in Introduction.

2) Section 2.1: There is a lack of explanation of the testing machine. More details, such as a schematic and the location of the water pressure measurements, need to be provided in order to understand the content of the paper.

3) Section 2.2: It is assumed that an in-situ claystone was used, but it is necessary to indicate at what depth and what the confining pressure and water pressure conditions were. The effect of sampling and loss of confining pressure should also be mentioned.

4) Section 2.2: Was the Claystone homogeneous? At least a cross-sectional photograph should be shown.

5) Section 3.2.1: It needs to be explained why axial strain occurs.

6) Section 4.1: The content of the back analysis is not clear at all. It should be explained in detail.

 

No problem.

Author Response

Dear Reviewer

We have replied to your suggestions in detail in the attachment and made modifications in the paper. Thank you for your work.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors,

I wish you  further success in your scientific work.

Reviewer 2 Report

The reviewer felt that the peer review opinions were appropriately addressed.