Created a new damage model for explosive for LS-DYNA3D,taking advantageof the Taylor method aimed at the high gassy and low permeability coal seam,and numericallysimulated and analyzed the deep-hole presplitting explo...Created a new damage model for explosive for LS-DYNA3D,taking advantageof the Taylor method aimed at the high gassy and low permeability coal seam,and numericallysimulated and analyzed the deep-hole presplitting explosion.The entire processof explosion was represented,including cracks caused by dynamic pressure,transmissionand vibration superposition of stress waves,as well as cracks growth driven by gas generatedby explosion.The influence of the cracks generated in the process of explosion andthe performance of improving permeability caused by the difference of interval between.explosive holes were analyzed.A reasonable interval between explosive holes of deepholepresplitting explosions in high gassy and low permeability coal seams was proposed,and the resolution of gas drainage in high gassy and low permeability coal seam was putforward.展开更多
Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surfac...Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.展开更多
Roof layer presplitting blasting is widely employed in underground coal mines to prevent rockbursts and strong seismic events caused by roof fracturing.The critical factor in the process is forming a penetrating presp...Roof layer presplitting blasting is widely employed in underground coal mines to prevent rockbursts and strong seismic events caused by roof fracturing.The critical factor in the process is forming a penetrating presplitting surface between blastholes.Conventional blasting(CB)faces the challenge of disordered crack propagation,which does not guarantee the formation of penetrating cracks.This study proposes an innovative satellite empty-hole controlled blasting(SECB)technique,which involves placing empty-holes symmetrically above and below the blasthole in a direction perpendicular to the line connecting the blastholes.Emptyholes are used to reflectblast waves to promote longer cracks in the controlled direction.Numerical models of SECB and CB were developed using LS-DYNA software to validate the feasibility of the SECB technique.Results show that SECB achieves better blasting performance compared to CB,with a 27.61%increase in maximum crack length in the controlled direction.SECB generates higher and more slowly decaying tensile stress beyond the blasting crushed zone,contributing to longer directional cracks and fewer remaining cracks.Analysis of blasting parameters reveals that 1.25-1.75 is the optimal decoupled coefficientinterval,and SECB has the best blasting performance.Optimal crack propagation occurs when the satellite's empty-hole radius is approximately half the blasthole radius,with less inter-hole rock fragmentation.Effective crack control is achieved with a spacing between the satellite empty-hole and blasthole of 4-8 times the blasthole radius.These findingsshow that the SECB technique offers new insights for enhancing roof layer presplitting blasting effectiveness.展开更多
Surface mines continue to implement highwalls for several reasons, such as increasing recovery, improving margins, and justifying higher stripping ratios. Highwall stability is a complex issue that is dependent upon a...Surface mines continue to implement highwalls for several reasons, such as increasing recovery, improving margins, and justifying higher stripping ratios. Highwall stability is a complex issue that is dependent upon a variety of mining and geologic factors, and a safe design is necessary for a successful surface operation. To improve highwall stability, it is important to understand the connection between local geology and blasting. Explosives are employed throughout the mining industry for primary rock breakage. There are a number of controlled blasting techniques that can be implemented to improve highwall stability.These include line drilling, smooth wall blasting, trim blasting, buffer blasting, air decking, and presplitting. Each of these techniques have associated advantages and disadvantages. Understanding local geology is necessary for selecting the appropriate controlled blasting technique. Furthermore, understanding the limitations and conditions for successful implementation of each technique is necessary. A discussion of the impact of geologic conditions on highwall stability is provided. Additionally, discussion is provided for the successful incorporation of the controlled blasting techniques listed above, and the associated mining and geologic factors that influence the selection and design of controlled blasting plans.Finally, a new methodology is proposed.展开更多
A West Kentucky mine operation in No. 11 seam encountered floor heave, due to the localized increase in the thickness of the fireclay mine floor. Floor heave has overridden seals installed in two mined out panels. The...A West Kentucky mine operation in No. 11 seam encountered floor heave, due to the localized increase in the thickness of the fireclay mine floor. Floor heave has overridden seals installed in two mined out panels. The third seal's location was planned for isolating that area from the Mains. A plan of support has been developed to prevent repetition of the floor heave and related problems outby the seals. The applied ground control measures were successful. An attempt of a 3D numerical modeling was made; thus, it would match the observed behavior of the mine floor and could be used as a design tool in similar conditions. The paper describes sequence of events, an applied mitigation ground control system, and the first stage of numerical modeling.展开更多
基金Supported by the National Science Foundation of China(50534090,2007BAK28B01,2007BAK29B06)the Science Foundation of Anhui Province(050440403)Creative Team Plan for High School of Anhui(2006KJ005TD)
文摘Created a new damage model for explosive for LS-DYNA3D,taking advantageof the Taylor method aimed at the high gassy and low permeability coal seam,and numericallysimulated and analyzed the deep-hole presplitting explosion.The entire processof explosion was represented,including cracks caused by dynamic pressure,transmissionand vibration superposition of stress waves,as well as cracks growth driven by gas generatedby explosion.The influence of the cracks generated in the process of explosion andthe performance of improving permeability caused by the difference of interval between.explosive holes were analyzed.A reasonable interval between explosive holes of deepholepresplitting explosions in high gassy and low permeability coal seams was proposed,and the resolution of gas drainage in high gassy and low permeability coal seam was putforward.
文摘Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.
基金funded by the projects:National Natural Science Foundation of China(Grant No.52274098)National Key Research and Development Program of China(Grant No.2022YFC3004603)Jiangsu Province International Collaboration Program-Key National Industrial Technology Research And Development Cooperation projects(Grant No.BZ2023050).
文摘Roof layer presplitting blasting is widely employed in underground coal mines to prevent rockbursts and strong seismic events caused by roof fracturing.The critical factor in the process is forming a penetrating presplitting surface between blastholes.Conventional blasting(CB)faces the challenge of disordered crack propagation,which does not guarantee the formation of penetrating cracks.This study proposes an innovative satellite empty-hole controlled blasting(SECB)technique,which involves placing empty-holes symmetrically above and below the blasthole in a direction perpendicular to the line connecting the blastholes.Emptyholes are used to reflectblast waves to promote longer cracks in the controlled direction.Numerical models of SECB and CB were developed using LS-DYNA software to validate the feasibility of the SECB technique.Results show that SECB achieves better blasting performance compared to CB,with a 27.61%increase in maximum crack length in the controlled direction.SECB generates higher and more slowly decaying tensile stress beyond the blasting crushed zone,contributing to longer directional cracks and fewer remaining cracks.Analysis of blasting parameters reveals that 1.25-1.75 is the optimal decoupled coefficientinterval,and SECB has the best blasting performance.Optimal crack propagation occurs when the satellite's empty-hole radius is approximately half the blasthole radius,with less inter-hole rock fragmentation.Effective crack control is achieved with a spacing between the satellite empty-hole and blasthole of 4-8 times the blasthole radius.These findingsshow that the SECB technique offers new insights for enhancing roof layer presplitting blasting effectiveness.
文摘Surface mines continue to implement highwalls for several reasons, such as increasing recovery, improving margins, and justifying higher stripping ratios. Highwall stability is a complex issue that is dependent upon a variety of mining and geologic factors, and a safe design is necessary for a successful surface operation. To improve highwall stability, it is important to understand the connection between local geology and blasting. Explosives are employed throughout the mining industry for primary rock breakage. There are a number of controlled blasting techniques that can be implemented to improve highwall stability.These include line drilling, smooth wall blasting, trim blasting, buffer blasting, air decking, and presplitting. Each of these techniques have associated advantages and disadvantages. Understanding local geology is necessary for selecting the appropriate controlled blasting technique. Furthermore, understanding the limitations and conditions for successful implementation of each technique is necessary. A discussion of the impact of geologic conditions on highwall stability is provided. Additionally, discussion is provided for the successful incorporation of the controlled blasting techniques listed above, and the associated mining and geologic factors that influence the selection and design of controlled blasting plans.Finally, a new methodology is proposed.
文摘A West Kentucky mine operation in No. 11 seam encountered floor heave, due to the localized increase in the thickness of the fireclay mine floor. Floor heave has overridden seals installed in two mined out panels. The third seal's location was planned for isolating that area from the Mains. A plan of support has been developed to prevent repetition of the floor heave and related problems outby the seals. The applied ground control measures were successful. An attempt of a 3D numerical modeling was made; thus, it would match the observed behavior of the mine floor and could be used as a design tool in similar conditions. The paper describes sequence of events, an applied mitigation ground control system, and the first stage of numerical modeling.
