Research on the Twin-Link Stepping Temporary Support Mechanism and the Repeatable Supportability of the Roof in the Underground Excavation Roadway of Coal Mine

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article contains original numerical tests on determining the zone of destruction and displacements for an excavation protected with a temporary support in various types of roof rocks. The characteristics of process aging and timeline are worth highlighting, as they are interesting in terms of improving the mining work schedule. Some minor comments might be useful to improve the paper: 

1. In the introduction it should be added some information about the daily progress of preparatory works using mechanical mining and explosives; 

2. In the subsection 2.1, write what is the maximum inclination of the excavation along rise and dip at 8the twin-link stepping temporaty support can work; 

3. In the subsection 2.3. please add a few words about dealing with roof falls - are the workings specially protected in any way; 

4. In the subsection 3.1, please write more clearly what type of contact was modeled between the support and the rock mass and between the individual layers in the false-basic-direct roof; 

5. In chapter four, please write what geometric and strength parameters were adopted for the anchor support; 

6. In subsections 4.1.1, 4.1.2 and 4.1.3, please write what bulk density was assumed for sandstone, sandy mudstone and mudstone and whether these were parameters for dry or wet layers; 

7. In chapter five on the analysis, it is worth mentioning that the schedule of preparatory works should also take into account delays related to natural hazards such as tremors, water intrusion and explosive gases. Furthermore please add informations about fault analysis in heavy equipment in 4.0 industry (doi:10.3390/en15176263);

8. In the conclusions, please add one statement regarding the comparison of the time needed to protect the excavations with traditional support and the proposed solution.

Author Response

Comment # 1* In the introduction it should be added some information about the daily progress of preparatory works using mechanical mining and explosives.

Authors’ response:

Thank you for your insightful feedback. We have carefully considered your suggestion regarding the introduction and have made revisions accordingly.

Comment # 2* In the subsection 2.1, write what is the maximum inclination of the excavation along rise and dip at 8the twin-link stepping temporary support can work;

Authors’ response:

Thank you for your feedback. We have addressed this concern by providing detailed information in subsection 2.1 of the manuscript regarding the maximum inclination along both rise and dip where the twin-link stepping temporary support can effectively operate.

Comment # 3* In the subsection 2.3. please add a few words about dealing with roof falls - are the workings specially protected in any way;

Authors’ response:

In subsection 2.3, a few words have been added to address the topic of dealing with roof falls and the protection measures for the workings. The updated sentence is as follows:

"In the event of a roof fall, the workings are specially protected by the duplex stepped temporary support, which can employ a safety relief valve to gradually release pressure, ensuring that the roadway does not experience abrupt collapse."

Comment # 4* In the subsection 3.1, please write more clearly what type of contact was modeled between the support and the rock mass and between the individual layers in the false-basic-direct roof;

Authors’ response:

Thank you for your suggestion. We have included additional details on the various contact types in the numerical modeling of the surrounding rock and support in Section 3.2 of the manuscript.

Comment # 5* In chapter four, please write what geometric and strength parameters were adopted for the anchor support;

Authors’ response:

Thank you for your suggestion. In the section of establishing numerical models in the third chapter of the manuscript, I have supplemented the relevant parameters of anchor support.

Comment # 6* In subsections 4.1.1, 4.1.2 and 4.1.3, please write what bulk density was assumed for sandstone, sandy mudstone and mudstone and whether these were parameters for dry or wet layers;

Authors’ response:

Thank you for your suggestion. I have added the parameters for rock bulk density and properties in Table 1 of the fourth chapter.

Comment # 7* In chapter five on the analysis, it is worth mentioning that the schedule of preparatory works should also take into account delays related to natural hazards such as tremors, water intrusion and explosive gases. Furthermore please add informations about fault analysis in heavy equipment in 4.0 industry (doi:10.3390/en15176263);

Authors’ response:

Thank you for your suggestion. In response to your advice and with the aim of enhancing the cohesiveness of the article, we have integrated pertinent research and literature into the introductory section.

Comment # 8* In the conclusions, please add one statement regarding the comparison of the time needed to protect the excavations with traditional support and the proposed solution.

Authors’ response:

In accordance with your valuable suggestion, we have incorporated pertinent descriptions within the concluding section.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This research employs numerical simulation methodology based on the principles of stepped temporary support. It investigates the repetitiveness of support for various roadway roofs and establishes the applicable scope of stepped temporary support for roof conditions. The outcomes of this study effectively address the essential challenge faced during the practical implementation of stepped temporary support.

 

The authors first designed and developed a double-bonded temporary support rig to establish a new process that integrates excavation, temporary support and anchoring operations. Second, to evaluate the suitability of the stepped temporary support for the pavement roof, they constructed a numerical model of the operation of the stepped temporary support based on the principle of the stepped temporary support and used 3DEC software. Through an analysis of the underground conditions, they investigated the repeatability of the support for different roof rock types, thicknesses, and depths, obtaining a range of sustainable roof support and applicable conditions for a double link temporary support.

 

This study provides the necessary conditions for the implementation of the complete equipment of the two-way stepping temporary support system. The new processes, equipment, and research methods presented in this paper provide opportunities for application in similar operational pathways.

 

Figure 3. Diagram of the drilling and anchoring vehicle - mark with arrows the basic elements of the vehicle, devices for drilling and anchoring.

 

Figure 5. Schematic diagram of traditional serial operations for comprehensive excavation roads - perhaps it is better to use the term presentation or an adequate term instead of the term diagram.

Author Response

Comment # 1* Figure 3. Diagram of the drilling and anchoring vehicle - mark with arrows the basic elements of the vehicle, devices for drilling and anchoring.

Authors’ response:

Thank you for your suggestion. Following your advice, we have added labels to denote the fundamental components of the drilling and anchoring vehicle depicted in Figure 3.

Comment # 2* Figure 5. Schematic diagram of traditional serial operations for comprehensive excavation roads - perhaps it is better to use the term presentation or an adequate term instead of the term diagram.

Authors’ response:

Thank you for your suggestion. We have incorporated your feedback and made revisions to the terminology used in the description of Figure 3.

Author Response File: Author Response.pdf