Research on the Key Technology of Gob-Side Entry Retaining by Roof Cutting for Thick and Hard Sandstone Roofs

Round 1

Reviewer 1 Report

The paper should be improved according to the comments below:

       (1)    Your literature survey needs improvement; please expand it.

       (2) Please, kindly look at the numbering of your article carefully to avoid misleading. 

      (3)  Avoid lumping references. Instead, summarize the main contribution of each referenced paper in a separate sentence. Please carefully go through the entire manuscript.

       (4)  For the result and discussion, the number of references is a bit low for such article. Please ensure all sections are adequately cited.

        (5)   A concise summary of conclusions on the novelty should be at the end of the manuscript.

Author Response

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Research on key technology of Gob-Side Entry retaining by roof cutting for thick and hard sandstone roof” (ID: sustainability-1833644). The comments are both valuable and very helpful for revising and improving our paper. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:

Responds to the reviewer’s comments:

1. Your literature survey needs improvement; please expand it.

Response:

We have added references as follows:

[27] Wang YJ, Liu JN, Yang J et al (2020) Stability characteristics of a fractured high roof under nonpillar mining with an automatically formed roadway by using a visualized discrimination approach. ENERGY SCI ENG. 8(5): 1541-1553

[31] Wojtecki L, Mendecki MJ, Golda I et al (2020) The Seismic Source Parameters of Tremors Provoked by Long-Hole Destress Blasting Executed During the Longwall Mining of a Coal Seam Under Variable Stress Conditions. PURE APPL GEOPHYS. 177(12): 5723-5739

[32] Xiang Z, Zhang N, Xie ZZ et al (2021) Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study. APPL SCI-BASEL. 11(9): https://doi.10.3390/app11094125

[33] Zhao D, Shen ZY, Li MH et al (2022) Study on parameter optimization of deep hole cumulative blasting in low permeability coal seams. SCI REP-UK. 8(1): https://doi.10.1038/s41598-022-09219-4

[34] Bai YS, Hu YQ (2018) Overlying Strata Movement of Below Protective Seam. J COASTAL RES. 83: 193-198

2. Please, kindly look at the numbering of your article carefully to avoid misleading.

We have numbered the headings by (1. Introduction) as stated.

3. Avoid lumping references. Instead, summarize the main contribution of each referenced paper in a separate sentence. Please carefully go through the entire manuscript.

We have avoided lumping references.

4. For the result and discussion, the number of references is a bit low for such article. Please ensure all sections are adequately cited.

We have added references as follows:

[27] Wang YJ, Liu JN, Yang J et al (2020) Stability characteristics of a fractured high roof under nonpillar mining with an automatically formed roadway by using a visualized discrimination approach. ENERGY SCI ENG. 8(5): 1541-1553

[31] Wojtecki L, Mendecki MJ, Golda I et al (2020) The Seismic Source Parameters of Tremors Provoked by Long-Hole Destress Blasting Executed During the Longwall Mining of a Coal Seam Under Variable Stress Conditions. PURE APPL GEOPHYS. 177(12): 5723-5739

[32] Xiang Z, Zhang N, Xie ZZ et al (2021) Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study. APPL SCI-BASEL. 11(9): https://doi.10.3390/app11094125

[33] Zhao D, Shen ZY, Li MH et al (2022) Study on parameter optimization of deep hole cumulative blasting in low permeability coal seams. SCI REP-UK. 8(1): https://doi.10.1038/s41598-022-09219-4

[34] Bai YS, Hu YQ (2018) Overlying Strata Movement of Below Protective Seam. J COASTAL RES. 83: 193-198

5. A concise summary of conclusions on the novelty should be at the end of the manuscript.

We have revised the conclusions as follows:

• The LS-DYNA numerical simulation software was used to analyze the blasting ef-fect under two working conditions with and without the energy-gathering pipe. The results showed that the surrounding rock cracks in a single horizontal direc-tion under the action of the detonation wave when using the energy-gathering pipe, which could achieve the purpose of directional roof cutting.
• By theoretical analysis and numerical simulation, it was determined that the op-timal height of roof cutting was 16m, and the optimal angle of roof cutting was 15°. The FLAC3D numerical simulation software was used to analyze the stress distri-bution of the working face. The results showed that the vertical stress near the roof cutting side was much smaller than the other side without roof cutting. The effect of pressure relief by roof cutting was good.
• It was proposed to use deep hole loosening blasting to make the thick and hard sandstone roof collapsed in time to filled the gob. A group of blasting hole was ar-ranged every 20 m in the roadway with roof cutting, and each group of blasting hole consists of two blasting holes. The depth of the #1 blasting hole was 47 m, and the angle with the horizontal direction was 20°; the depth of the #2 blasting hole was 65 m, and the angle with the horizontal direction was 15°. The two blast-ing holes were arranged perpendicular to the advancing direction of the working face, and the diameters of the blasting hole were both 50 mm.
• The field test of 7135 ventilation roadway showed that: the blasting with the ener-gy-gathering pipe had a good effect of directional slitting; after deep hole loosen-ing blasting, the thick and hard sandstone roof could collapse and fill the gob in time; the hydraulic support resistance of the working face in the side with roof cutting was much smaller than that of the side without roof cutting, and the effect of pressure relief by roof cutting was good.

Author Response File: Author Response.pdf

Reviewer 2 Report

I have carefully read the manuscript sustainability-1833644 entitled “Research on key technology of Gob-Side Entry retaining by roof cutting for thick and hard sandstone roof “. In this work, the key technology of pre-split blasting in the application of gob-side entry retaining by roof cutting for thick and hard sandstone roof was studied. The blasting effect of the energy-gathering pipe was analyzed using the LS-DYNA. The effect of pressure relief by roof cutting was verified by FLAC3D. A field test was carried out in the 7135-ventilation roadway of Qidong Coal Mine, China. Different results have been raised and thoroughly discussed. The optimal cutting height and the optimal cutting angle were found to be 16 m and 15°, respectively. Deep hole loosening blasting was proposed to solve the problem that the sandstone with thick hard roof is difficult to collapse. In addition, various recommendations were presented based on the results of the field test in the ventilation roadway of Qidong Coal Mine. The manuscript is good and can add to the literature, thanks to the authors. I have the following comments suggestions:

·         I suggest mentioning the country (China) whenever the name of (Qidong Coal Mine) is stated or at least one time in the abstract and at its first time of appearance in the main text (Page 1 L19 and Page 3 L74).

·         Numbering the headings should be starting by (1. Introduction) not (0. Introduction) as you stated. Would you please check and revise?

·         Some Figures are not clear for me as a reader and require improvement:

o    The red and blue lines, dashed lines, and arrows, in Figure 1 are not obvious, would you please check?

o    The color legends in Figures 5, 7, 10, and 11 are not obvious for me as a reader, would you please check?

o    The resolution of different figures is poor, which should be improved in the submitted manuscripts (Figure 10 and 11 for example), would you please check?

o    Figure 13: Would you please check that on the right-hand side, the number of explosives is presented in Chinese? Additionally, it has very small font and not obvious?

o    Would you please check that the resolution of Figure 15 is poor and very small fonts were used inside?

·         Would you please check that you need to add numbers (Eq. 1, Eq. 2, …etc.) for each equation in scientific manuscripts and cite them in the main text? The authors stated 4 equations (in Page 6 and Page 9) that should be numbered and cited, would you please check?

·         P8 L207 to L216: Would you please check cutting the long sentences into small ones?

·         In the references’ list: Would you please be consistent and use the same citation style? For example, in some reference citation, you are stating DOI; however, you are missing in others. Another example, you are stating the volume and issue of journals in some citations and missing in others. Would you please check and revise?

Author Response

Dear Editors and Reviewers:

Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Research on key technology of Gob-Side Entry retaining by roof cutting for thick and hard sandstone roof” (ID: sustainability-1833644). The comments are both valuable and very helpful for revising and improving our paper. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewers’ comments are as flowing:

Responds to the reviewer’s comments:

1. I suggest mentioning the country (China) whenever the name of (Qidong Coal Mine) is stated or at least one time in the abstract and at its first time of appearance in the main text (Page 1 L19 and Page 3 L74).

Response:

We have mentioned the country (China) in the main text (Page 1 L19 and Page 3 L74).

2. Numbering the headings should be starting by (1. Introduction) not (0. Introduction) as you stated. Would you please check and revise?

Response:

We have numbered the headings by (1. Introduction) as stated.

3. Some Figures are not clear for me as a reader and require improvement:

The red and blue lines, dashed lines, and arrows, in Figure 1 are not obvious, would you please check?

The color legends in Figures 5, 7, 10, and 11 are not obvious for me as a reader, would you please check?

The resolution of different figures is poor, which should be improved in the submitted manuscripts (Figure 10 and 11 for example), would you please check?

Figure 13: Would you please check that on the right-hand side, the number of explosives is presented in Chinese? Additionally, it has very small font and not obvious?

Would you please check that the resolution of Figure 15 is poor and very small fonts were used inside?

Response:

We have improved the Figures as follows:

Figure 1. Process flow of gob-side entry retaining by roof cutting.

(a) t-0.02 ms                                (b) t=0.12 ms                            (c) t=0.22 ms

Figure 5. Stress evolution process of non-energy-gathering blasting.

(a) t-0.02 ms                                (b) t=0.10 ms                            (c) t=0.18 ms

Figure 7. Stress evolution process of energy-gathering blasting.

(a) The angle is 5°                                            (b) The angle is 10°

(c) The angle is 15°                                           (d) The angle is 20°

Figure 10. Crack development process of energy-gathering blasting.

(a) The working face advanced 40m              (b) The working face advanced 80m

(c) The working face advanced 120m             (d) The working face advanced 160m

Figure 11. Vertical stress distribution during mining.

(a) The effect of the fracturing           (b) The quantity of explosive

Figure 13. The Scheme 4.

Figure 15. Engineering application.

4. Would you please check that you need to add numbers (Eq. 1, Eq. 2, …etc.) for each equation in scientific manuscripts and cite them in the main text? The authors stated 4 equations (in Page 6 and Page 9) that should be numbered and cited, would you please check?

Response:

We have added numbers for each equation and added references as follows:

[27] Wang YJ, Liu JN, Yang J et al (2020) Stability characteristics of a fractured high roof under nonpillar mining with an automatically formed roadway by using a visualized discrimination approach. ENERGY SCI ENG. 8(5): 1541-1553

[32] Xiang Z, Zhang N, Xie ZZ et al (2021) Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study. APPL SCI-BASEL. 11(9): https://doi.10.3390/app11094125

[33] Zhao D, Shen ZY, Li MH et al (2022) Study on parameter optimization of deep hole cumulative blasting in low permeability coal seams. SCI REP-UK. 8(1): https://doi.10.1038/s41598-022-09219-4

[34] Bai YS, Hu YQ (2018) Overlying Strata Movement of Below Protective Seam. J COASTAL RES. 83: 193-198

5. P8 L207 to L216: Would you please check cutting the long sentences into small ones?

Response:

We have cut the long sentences into small ones as follows:

As shown in Figure 11, when the working face was advanced 40 m, the vertical stress value of the working face with roof cutting was 9.22 MPa, and the vertical stress value of the working face without roof cutting was 14.13 MPa. When the working face was advanced 80 m, the vertical stress value of the working face with roof cutting was 8.43 MPa, and the vertical stress value of the working face without roof cutting was 13.22 MPa. When the working face was advanced 120 m, the vertical stress value of the working face with roof cutting was 7.89 MPa, and the vertical stress value of the working face without roof cutting was 13.15 MPa. When the working face was advanced 160 m, the vertical stress value of the working face with roof cutting was 9.13 MPa, and the vertical stress value of the working face without roof cutting was 14.25 MPa.

6. In the references’ list: Would you please be consistent and use the same citation style? For example, in some reference citation, you are stating DOI; however, you are missing in others. Another example, you are stating the volume and issue of journals in some citations and missing in others. Would you please check and revise?

Response:

We have revised the references.

Author Response File: Author Response.pdf