Experimental Investigation of Non-Linear Seepage Characteristics in Rock Discontinuities and Morphology of the Shear Section in the Shear Process

Round 1

Reviewer 1 Report

This thesis provides an experimental study of the non-linear seepage characteristics of the structural face of the rock during shear and the morphological characteristics of the shear section, which is of some added significance to the study of rock engineering stability. There are parts of this manuscript that require further clarification.

(1) Section 2.1, what are the specifications for the selection of materials for cement mortar fabrication, the strength of the completed specimens should be different for different materials and such information should be added in the article.

(2) Fig. 4 (a) shows the variation characteristics of shear stress with shear displacement under the conditions of applying osmotic water pressure and not applying osmotic water pressure. For repeated samples on the surface of the same wave angle structure, please explain why the shear stress is different at the beginning of the test (the shear displacement is 0 mm to 5 mm).

(3) In section 3.2.1, the Forchheimer equation was used to fit the test data in the description of the non-linear seepage characteristics; what was the reason for choosing this equation? What is the difference with the commonly used Darcy's equation?

(4) The abstract in the article should be refined again.

(5) Validate technical terms in the article, such as non-linear seepage, critical Reynolds number and anisotropy.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

In this study, structural surfaces with different undulation angles were repeatedly fabricated using cement mortar, and seepage tests at different shear displacements were carried out to analyse the effect of undulation angle and shear displacement on the shear mechanical properties, non-linear seepage characteristics and three-dimensional morphological characteristics of the structural surfaces. Some minor modifications are required to improve this manuscript.

(1) The structural surface used in the tests is a cement mortar material, what are the principles of material proportion selection? Are the results of this paper more reliable than those of the rock structural plane tests?

(2) In the schematic diagram of permeability test in Figure 3, after conducting the seepage test at each shear displacement, the shear displacement changes again. Is there any water pressure at this time? Please add a penetration test procedure.

(3) Fig.4 (a) , there is a significant up and down fluctuation in shear stress observed at the set shear displacement, please explain the reason for this?

(4) Please add the range of application of equation (4).

(5) What is the critical Reynolds number range for linear and non-linear seepage in existing studies? What significance does the article study add to the existing studies.

Author Response

Please see the attachment.

Author Response File: Author Response.docx