Numerical and Field Investigations of Tremors Induced by Thick-Hard Strata Fracture
Round 1
Reviewer 1 Report
The manuscript can be accepted for publication after minor revision.
In the manuscript numerical calculations and field investigations were performed in order to analyze mining tremors induced by thick hard rock strata. Case study of hard coal mine located in China was presented.
The problem presented in the manuscript is important and actual. The paper is well written to demonstrate the idea and the experimental and computational results. The authors present their investigations in a logical and clear way. They cited references which are published in the international journals.
Some detailed suggestions and questions address to the authors are listed below:1. In the most of the pictures presenting eg. stresses there is no unit (eg. Fig 2, Fig 3).
2. In some literature sources there is no information in which journal the article was published, eg [13] - line 331
3. Fig 5 – units on vertical axes are missing
4. In my opinion, there is too little density of the mesh around the roadway in the model, which cause significant calculation errors and make it difficult to interpret the results. The density should be improved.
5. This work is based on a 2D modeling approach. Have you considered 3D simulations? What are the limitations of 2D simulations here?
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Reviewer 2 Report
Journal: Applied Sciences (ISSN 2076-3417)
Manuscript ID: applsci-1935043
Article: Title: Numerical and Field Investigations of Tremors Induced by Thick-hard Strata Fracture
Authors: Guo et al.
In this manuscript, authors have conducted Numerical and Field Investigations of Tremors Induced by Thick-hard Strata Fracture. With help of the simulation and field study, authors have revealed the laws and influencing factors of stress, deformation, fracture and energy caused by mining-induced tremors (red bed breaking). Main conclusion are 1) The tensile stress in the middle of thick- hard rock is concentrated, and the compressive stress is mainly concentrated on both sides of the goaf, which are prone to tensile and shear failure type caused by mining-induced tremors, respectively; 2) After the goaf was formed, the compressive stress around the roadway is transformed into tensile stress. When a strong mining-induced tremors occurs, the tensile stress further increases, meanwhile, when it exceeds the tensile strength of the surrounding rock of the roadway, the rockburst occurs; 3) The energy of mining-induced tremors released by shear failure is larger than that of tensile failure. With the increase of shear strength of roof, the released energy also increases; 4) Based on the frequency-spectrum analysis of the mining-induced tremors located in the extremely thick-hard overlying strata above the working face in the Baodian coal mine, the dynamic load generated by the tremors is superimposed on the high static stress of the roadway, and it’s very likely to induce the instability of the roadway.
I believe this this work is orign, well presented and fit with the scope of the applied Sciences journal. However, there are some major review points that must be tackled by author before accepting this manuscript as follow:
1- In Fig. 6 Evolution of maximum principal stress around the roadway. The figure 6 a to d is not well generated. There is a white empty box in the middle of each figure. These figures need to be corrected.
2- The result of this work should be compared with other reported studies. I suggest creating a summarized table comparing results of this work with other reported result especially for determine the laws and influencing factors of stress, deformation, fracture and energy caused by mining-induced tremors.
3- The English language through whole manuscript should be polished
Author Response
The response to your comment has been uploaded, we hope you are satisfied with it.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Authors have answered all comments properly. Thus, I recommend publishing this manuscript in its present form.
