Because of the complexity and variability of the mine underground roadway, roadway is required to be dynamically generated in 3-D display,viewpoint can be trans- formed to achieve the 3-D roaming effect,and can do int...Because of the complexity and variability of the mine underground roadway, roadway is required to be dynamically generated in 3-D display,viewpoint can be trans- formed to achieve the 3-D roaming effect,and can do interactive inquiries and positioning for the roadway.In terms of the requirements above,gave the comparatively detailed elaboration of the solution,using the open graphics library (OpenGL) and relying on VC++ 6.0 combined with Database Programming.Mainly establish the 3D model landscape of the underground roadway using OpenGL based on VC programming environment and MFC programming,elaborated the powerful 3D graphics library,i.e.OpenGL in detail, gave the algorithm which can realize the relative positioning and of arbitrary point and the roaming and so on in the mine roadway,and also solves illumination,turning,and other issues of the roadway model.展开更多
Overbreak and underbreak are the crucial problems during the blasting excavation of underground tunnels owing to their effects on the construction costs and operational safety.A critical challenge facing overbreak and...Overbreak and underbreak are the crucial problems during the blasting excavation of underground tunnels owing to their effects on the construction costs and operational safety.A critical challenge facing overbreak and underbreak control is the difficulty in developing guidelines with respect to various and complex engineering conditions.In this study,a series of field measurements of overbreak and underbreak using the Focus^(S)150 laser scanner were performed in a deep roadway of the Kaiyang phosphate mine,China.The distri-bution and extent of the overbreak and underbreak surrounding the roadway contour were accurately analyzed in accordance with the collected point cloud data.Subsequently,a simplified three-dimensional model was established to simulate the blasting excavation of pre-stressed roadway using the explicit dynamic analysis code LS-DYNA.A comparison of numerical and measurement results revealed that the proposed model was a reliable tool to simulate the overbreak and underbreak induced by blasting excavation.Thereafter,the influ-ences of uncontrollable geological factors such as in situ stress conditions and controllable blasting factors including contour hole spac-ing(S),charge concentration(b)and decoupled coefficient(f)as well as stemming were further numerically investigated.The simulation results indicated that the lateral pressure coefficient significantly affected the distribution pattern of the overbreak and underbreak,while the stress magnitude contributed to their extents.Moreover,a comparison of the simulation findings and the field measurement data indicated that the minimal extents of the overbreak and underbreak corresponding the optimal contour blasting results were obtained at S=0.70 m,b=0.9 kg/m and f=2.5,respectively.Furthermore,the contour blastholes stemmed with sand created smaller damage to the periphery rock mass of roadway and enhanced the utilization efficiency of explosive energy.The research findings of this study pro-vide important implications for similar blasting excavation projects.展开更多
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
Roof bolting has been used in underground entry(roadway)support in U.S.coal mines since the Coal Mine Health and Safety Act of 1969(US Congress,1977)recognized roof bolting as the only means of underground entry(roadw...Roof bolting has been used in underground entry(roadway)support in U.S.coal mines since the Coal Mine Health and Safety Act of 1969(US Congress,1977)recognized roof bolting as the only means of underground entry(roadway)support.For U.S.underground coal mines,roof bolting pattern is fixed at 44 ft(1.21.2 m),except in the Pittsburgh Seam where longwall mining is practiced,with occasional 3.64 ft(1.11.2 m)pattern.However,roof falls or roof failure often occurs in roof-bolted entries in U.S.coal mines.Roof falls can roughly be divided into four types:skin falls,large falls,cutter roofs,and massive falls.Based on this situation,the roof is initially strengthened by bolt based on suspension and friction mechanism.By comparing roof bolting patterns in different coal producing countries,bolt density in all other countries is much higher(except South Africa)than that used in the U.S.In spite of its long history of successful application with hundreds of millions of units installed,roof bolting design is still the lack of a commonly accepted method.展开更多
基金the Open Research Fund Program of the Geomatics and Applications Laboratory,Liaoning Technical University(2007010)the Important Laboratory of Liaoning Province Fund(20060370)
文摘Because of the complexity and variability of the mine underground roadway, roadway is required to be dynamically generated in 3-D display,viewpoint can be trans- formed to achieve the 3-D roaming effect,and can do interactive inquiries and positioning for the roadway.In terms of the requirements above,gave the comparatively detailed elaboration of the solution,using the open graphics library (OpenGL) and relying on VC++ 6.0 combined with Database Programming.Mainly establish the 3D model landscape of the underground roadway using OpenGL based on VC programming environment and MFC programming,elaborated the powerful 3D graphics library,i.e.OpenGL in detail, gave the algorithm which can realize the relative positioning and of arbitrary point and the roaming and so on in the mine roadway,and also solves illumination,turning,and other issues of the roadway model.
基金the National Natural Science Foundation of China(Grant Nos.11772357,12072376)the Fundamental Research Funds for the Central Universities of Central South University(Grant No.2021XQLH053).
文摘Overbreak and underbreak are the crucial problems during the blasting excavation of underground tunnels owing to their effects on the construction costs and operational safety.A critical challenge facing overbreak and underbreak control is the difficulty in developing guidelines with respect to various and complex engineering conditions.In this study,a series of field measurements of overbreak and underbreak using the Focus^(S)150 laser scanner were performed in a deep roadway of the Kaiyang phosphate mine,China.The distri-bution and extent of the overbreak and underbreak surrounding the roadway contour were accurately analyzed in accordance with the collected point cloud data.Subsequently,a simplified three-dimensional model was established to simulate the blasting excavation of pre-stressed roadway using the explicit dynamic analysis code LS-DYNA.A comparison of numerical and measurement results revealed that the proposed model was a reliable tool to simulate the overbreak and underbreak induced by blasting excavation.Thereafter,the influ-ences of uncontrollable geological factors such as in situ stress conditions and controllable blasting factors including contour hole spac-ing(S),charge concentration(b)and decoupled coefficient(f)as well as stemming were further numerically investigated.The simulation results indicated that the lateral pressure coefficient significantly affected the distribution pattern of the overbreak and underbreak,while the stress magnitude contributed to their extents.Moreover,a comparison of the simulation findings and the field measurement data indicated that the minimal extents of the overbreak and underbreak corresponding the optimal contour blasting results were obtained at S=0.70 m,b=0.9 kg/m and f=2.5,respectively.Furthermore,the contour blastholes stemmed with sand created smaller damage to the periphery rock mass of roadway and enhanced the utilization efficiency of explosive energy.The research findings of this study pro-vide important implications for similar blasting excavation projects.
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%.
文摘Roof bolting has been used in underground entry(roadway)support in U.S.coal mines since the Coal Mine Health and Safety Act of 1969(US Congress,1977)recognized roof bolting as the only means of underground entry(roadway)support.For U.S.underground coal mines,roof bolting pattern is fixed at 44 ft(1.21.2 m),except in the Pittsburgh Seam where longwall mining is practiced,with occasional 3.64 ft(1.11.2 m)pattern.However,roof falls or roof failure often occurs in roof-bolted entries in U.S.coal mines.Roof falls can roughly be divided into four types:skin falls,large falls,cutter roofs,and massive falls.Based on this situation,the roof is initially strengthened by bolt based on suspension and friction mechanism.By comparing roof bolting patterns in different coal producing countries,bolt density in all other countries is much higher(except South Africa)than that used in the U.S.In spite of its long history of successful application with hundreds of millions of units installed,roof bolting design is still the lack of a commonly accepted method.
