A Numerical Model for the Compressive Behavior of Granular Backfill Based on Experimental Data and Application in Surface Subsidence
Round 1
Reviewer 1 Report
This paper is well written, and it can contribute knowledge to literature and practice. The reviewer would like to have some comments as follows.
- 2.3 experiment methods and procedures. Please add standards or references for loading rate 1mm/min.
- please clearly add the boundary condition of the model in FLAC-3D.
- The reviewer found some typos and grammar mistakes, please kindly check the manuscript carefully.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
I think this paper is generally well written. I would like to comment on a few points which it could be improved.
■Section 2.1; It is advisable to cite any studies that have been used as reference in setting up the testing system, or to state if they are original to the authors.
■P. 3, L1; A brief description of the principles of the AE monitoring method would help the reader to understand it.
■Fig. 1; It is easier to understand if a scale (e.g. 1m) is shown in the diagram to give an indication of the size.
■Section 3.2; There is a lack of description of FLAC3D; why not add a description of the basic equations used by FLAC3D and cite examples of research using FLAC3D?
■Fig. 14; it would be better to indicate the scale as in the remarks to Fig. 1.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The experimental set up to test the behaviour of granular filling material has been used to evolve the insights on deformation modulus of granular materials of different particle size, shapes and therafter the variable deformation modulus has been simulated by numerical simulation with, FLAC 3D software to develop the constitutive equations and understand the behaviour of granular backfills under different loading conditions and assess its impact on the surface subsidence with goaf of different heights. Following specific observations are critical to provide better objectivity and scientificity to the paper:
(i) English is extremely poor and makes it tough to understand the scope of the paper in various sections and also in evolving the focus of the paper.
(ii) Authors have mentioned that with the cemented backfills in the nickel mines, the subsidence occured even after 18 years then how the importance of investigating the granular backfills provides a breakthrough. Does the study any other practical relevance other than utilizing the solid waste that too irrationally? It would have been much better to undertake such studies on cemented or pasted backfills to improve the techno-economic viability of the experimental and numerical work for industrial use.
(iii) The paper is mostly silent on granular particle shape, stiffness, dimension in the discussion and conclusion part. Further, the conclusions drawn by the so called novel method of incorporating the concept of variable deformation modulus are natural, conventional and not unique.
(iv) The findings could have been validated in real time case in a suitable stope.
(v) The deployment of AE and strain gauges in the experimental set-up is normal practice. However, the correlation between the AE and strain gauge data could be included to make the study more scientific. The strain gauge data and AE dat of the experimental set up have not been clearly discussed.
(vi) Surface subsidence is discussed but primarily the critical data and discussion of the deformation modulus on immediate stope back and walls is highly important from operational view point, especially for deeper workings. It needs to be described through experimental and numerical studies.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The author has addressed all comments from the reviewer.
Now the paper can be accepted for publication.
Reviewer 2 Report
The manuscript has been well revised.
Reviewer 3 Report
Satisfactory for publication now.
