Roof bolts such as rock bolts and cable bolts provide structural support in underground mines.Frequent assessment of these support structures is critical to maintain roof stability and minimise safety risks in undergr...Roof bolts such as rock bolts and cable bolts provide structural support in underground mines.Frequent assessment of these support structures is critical to maintain roof stability and minimise safety risks in underground environments.This study proposes a robust workflow to classify roof bolts in 3 D point cloud data and to generate maps of roof bolt density and spacing.The workflow was evaluated for identifying roof bolts in an underground coal mine with suboptimal lighting and global navigation satellite system(GNSS)signals not available.The approach is based on supervised classification using the multi-scale Canupo classifier coupled with a random sample consensus(RANSAC)shape detection algorithm to provide robust roof bolt identification.The issue of sparseness in point cloud data has been addressed through upsampling by using a moving least squares method.The accuracy of roof bolt identification was measured by correct identification of roof bolts(true positives),unidentified roof bolts(false negatives),and falsely identified roof bolts(false positives)using correctness,completeness,and quality metrics.The proposed workflow achieved correct identification of 89.27%of the roof bolts present in the test area.However,considering the false positives and false negatives,the overall quality metric was reduced to 78.54%.展开更多
The anchoring eccentricity of the bolt and cable bolt is a common problem in geotechnical support engineering and affects the ability of the bolt and cable bolt to control the rock mass to a certain extent.This paper ...The anchoring eccentricity of the bolt and cable bolt is a common problem in geotechnical support engineering and affects the ability of the bolt and cable bolt to control the rock mass to a certain extent.This paper reports on numerical simulation and laboratory experiments conducted to clarify the effect of eccentricity on the anchoring quality of the bolt and cable bolt,and to establish an effective solution strategy.The results reveal that the anchoring eccentricity causes unbalanced stress distribution and the uncoordinated deformation of the resin layer,which results in higher stress and greater deformation of the resin layer at the near side of the rod body.Additionally,as the degree of anchoring eccentricity increases,the effect becomes more significant,and the resin layer of the anchoring system becomes more likely to undergo preferential failure locally,which weakens the load-bearing performance of the anchoring system.This paper develops an innovative bolt anchoring rectifying device(B-ARD)and cable bolt anchoring rectifying device(C-ARD)on the basis of the structural characteristics of the bolt and cable bolt to better ensure the anchoring effect of them.The working effects of these two devices were verified in detailed experiments and analysis.The experimental results show that the anchoring rectifying devices(ARD)improve and ensure the anchoring concentricity of the bolt and cable bolt,which will help improve the supporting performance of them.The paper provides a convenient and effective method for improving the anchoring concentricity of the bolt and cable bolt,and provides a concept and reference for technical research on improving the effect of roof bolting.展开更多
Multi-factor productivity(MFP) in underground coal mining has been on the decline for the last decade.The mining industry requires a viable and sustainable approach to overcome the current downtrend. This is only poss...Multi-factor productivity(MFP) in underground coal mining has been on the decline for the last decade.The mining industry requires a viable and sustainable approach to overcome the current downtrend. This is only possible by concurrently focussing on productivity improvement and operating costs reduction,delivered through both incremental and step change technology development. Four technologies are presented in this paper: fibre optic borehole sensing has been demonstrated to reveal detailed information about gas flow influx, water level and borehole blockage events occurring along the length of a surfaceto-inseam lateral. Fibre optic gas sensing has also been investigated, and this technology promises a remote, intrinsically safe, distributed solution. Recent developments in continuous water jet drilling technology have demonstrated a step change increase in drilling rates and flexibility for coal seam degassing,applicable in both surface-to-inseam and underground in-seam applications. The application of water jet technology to the cable bolt drilling problem offers potential to address a serious health and safety and productivity issue in the roadway development process.展开更多
Longwall mining is by far the most common method of underground coal extraction in Australia. The industry trends and expectations are placing increasing emphasis on the reliability and productivity of these operation...Longwall mining is by far the most common method of underground coal extraction in Australia. The industry trends and expectations are placing increasing emphasis on the reliability and productivity of these operations. The longwalls are becoming wider and longer while retreat rates are continuously increasing due to significant improvements achieved in longwall equipment reliability and automation.This increased longwall productivity is placing significant emphasis on the reliability of longwall panel development. Although there have been significant improvements in the reliability of continuous miners and hydraulic drill rigs,the traditional resin encapsulated bolt installation is still the principal method used in all major coal-producing countries around the world. Anglo American realised an opportunity existed to introduce an alternative roof bolt installation technique called ‘‘spin to stall" in Australia.Spin to stall was first introduced in Anglo American Coal in South Africa where it has been successfully used for over a decade,though implementation of South African spin to stall resin in Australia has proven to be near impossible due to a significant difference in geotechnical conditions,mining method,and,subsequently,roof bolting equipment. Therefore,a new spin to stall development project was initiated between Anglo American Coal and Jennmar Australia(SPIN2STALLò). This paper summarises the journey of this project,the results,and the successful implementation of spin to stall achieved at Grasstree Mine.展开更多
基金financially supported by the Australian Coal Industry’s Research Program(ACARP)Project C27057。
文摘Roof bolts such as rock bolts and cable bolts provide structural support in underground mines.Frequent assessment of these support structures is critical to maintain roof stability and minimise safety risks in underground environments.This study proposes a robust workflow to classify roof bolts in 3 D point cloud data and to generate maps of roof bolt density and spacing.The workflow was evaluated for identifying roof bolts in an underground coal mine with suboptimal lighting and global navigation satellite system(GNSS)signals not available.The approach is based on supervised classification using the multi-scale Canupo classifier coupled with a random sample consensus(RANSAC)shape detection algorithm to provide robust roof bolt identification.The issue of sparseness in point cloud data has been addressed through upsampling by using a moving least squares method.The accuracy of roof bolt identification was measured by correct identification of roof bolts(true positives),unidentified roof bolts(false negatives),and falsely identified roof bolts(false positives)using correctness,completeness,and quality metrics.The proposed workflow achieved correct identification of 89.27%of the roof bolts present in the test area.However,considering the false positives and false negatives,the overall quality metric was reduced to 78.54%.
基金This study was supported by the National Natural Science Foundation of China(No.52074102)Foundation for Distinguished Young Talents in Higher Education of Henan(No.212300410006)+1 种基金Foundation for the Science and Technology Innovation Talents Project of Universities in Henan(No.22HASTIT010)Special Funds for Fundamental Scientific Research Expenses of Universities in Henan(No.NSFRF210202).
文摘The anchoring eccentricity of the bolt and cable bolt is a common problem in geotechnical support engineering and affects the ability of the bolt and cable bolt to control the rock mass to a certain extent.This paper reports on numerical simulation and laboratory experiments conducted to clarify the effect of eccentricity on the anchoring quality of the bolt and cable bolt,and to establish an effective solution strategy.The results reveal that the anchoring eccentricity causes unbalanced stress distribution and the uncoordinated deformation of the resin layer,which results in higher stress and greater deformation of the resin layer at the near side of the rod body.Additionally,as the degree of anchoring eccentricity increases,the effect becomes more significant,and the resin layer of the anchoring system becomes more likely to undergo preferential failure locally,which weakens the load-bearing performance of the anchoring system.This paper develops an innovative bolt anchoring rectifying device(B-ARD)and cable bolt anchoring rectifying device(C-ARD)on the basis of the structural characteristics of the bolt and cable bolt to better ensure the anchoring effect of them.The working effects of these two devices were verified in detailed experiments and analysis.The experimental results show that the anchoring rectifying devices(ARD)improve and ensure the anchoring concentricity of the bolt and cable bolt,which will help improve the supporting performance of them.The paper provides a convenient and effective method for improving the anchoring concentricity of the bolt and cable bolt,and provides a concept and reference for technical research on improving the effect of roof bolting.
基金Australian Coal Association Research Program (ACARP)CRCMining’s Coal Technologies and Fugitive Emissions Research programThe University of Queensland
文摘Multi-factor productivity(MFP) in underground coal mining has been on the decline for the last decade.The mining industry requires a viable and sustainable approach to overcome the current downtrend. This is only possible by concurrently focussing on productivity improvement and operating costs reduction,delivered through both incremental and step change technology development. Four technologies are presented in this paper: fibre optic borehole sensing has been demonstrated to reveal detailed information about gas flow influx, water level and borehole blockage events occurring along the length of a surfaceto-inseam lateral. Fibre optic gas sensing has also been investigated, and this technology promises a remote, intrinsically safe, distributed solution. Recent developments in continuous water jet drilling technology have demonstrated a step change increase in drilling rates and flexibility for coal seam degassing,applicable in both surface-to-inseam and underground in-seam applications. The application of water jet technology to the cable bolt drilling problem offers potential to address a serious health and safety and productivity issue in the roadway development process.
文摘Longwall mining is by far the most common method of underground coal extraction in Australia. The industry trends and expectations are placing increasing emphasis on the reliability and productivity of these operations. The longwalls are becoming wider and longer while retreat rates are continuously increasing due to significant improvements achieved in longwall equipment reliability and automation.This increased longwall productivity is placing significant emphasis on the reliability of longwall panel development. Although there have been significant improvements in the reliability of continuous miners and hydraulic drill rigs,the traditional resin encapsulated bolt installation is still the principal method used in all major coal-producing countries around the world. Anglo American realised an opportunity existed to introduce an alternative roof bolt installation technique called ‘‘spin to stall" in Australia.Spin to stall was first introduced in Anglo American Coal in South Africa where it has been successfully used for over a decade,though implementation of South African spin to stall resin in Australia has proven to be near impossible due to a significant difference in geotechnical conditions,mining method,and,subsequently,roof bolting equipment. Therefore,a new spin to stall development project was initiated between Anglo American Coal and Jennmar Australia(SPIN2STALLò). This paper summarises the journey of this project,the results,and the successful implementation of spin to stall achieved at Grasstree Mine.
