Most of the existing studies on tunnel blast wave are based on spherical or grouped charges,however,conventional weapons are mostly cylindrical rather than spherical.In order to analyze the impact of cylindrical charg...Most of the existing studies on tunnel blast wave are based on spherical or grouped charges,however,conventional weapons are mostly cylindrical rather than spherical.In order to analyze the impact of cylindrical charges on the tunnel blast wave loads and to develop a quantitative calculation method,this study carried out experimental and numerical research.Initially,external explosion experiments were conducted using both 35 kg spherical charges and cylindrical charges with aspect ratio of 4.8 at two different distances from the tunnel entrance.Comparative analysis of the blast wave parameters in the tunnel revealed that the explosive equivalent of the cylindrical charges was significantly higher than that of the spherical charges.To address this,an equivalent coefficient k based on the spherical charges was proposed for the cylindrical charges.Subsequently,numerical simulations were conducted for the experimental conditions,and the numerical simulation results match the experiments well.Through numerical calculations,the reliability of the equivalent coefficient k under the experimental conditions was verified,and comparison analysis indicated that the explosion energy of cylindrical charges spreads more radially,resulting in more explosion energy entering the tunnel,which is the fundamental reason for the increase in tunnel blast wave loads.Additionally,analyzing the explosion energy ratio entering the tunnel is an effective method for calculating the equivalent coefficient k.Finally,through more than one hundred sets of numerical calculation results,the impact of the proportional distance l and the ratio of charge mass to the tunnel cross-section dimension 4 on the equivalence coefficients k was investigated.An empirical formula for the equivalence coefficient k was derived through fitting,and the accuracy of the formula was validated through literature experimental results.The research findings of this paper will provide valuable guidance for the calculation of blast wave loads in tunnel.展开更多
Under the fact that considerable explo ration and production of unconventional re sources and wo rsening global climate,reducing carbon emission and rationally utilizing carbon resources have been drawn increasing att...Under the fact that considerable explo ration and production of unconventional re sources and wo rsening global climate,reducing carbon emission and rationally utilizing carbon resources have been drawn increasing attention.Supercritical CO_(2)(SC-CO_(2)) has been proposed as anhydrous fracturing fluid to develop unconventional reservoirs,since its advantages of reducing water consumption,reservoir contamination etc.Well understanding of SC-CO_(2)fracturing mechanism and key influencing factors will exert significant impact on the application of this technology in the field.In this paper,the fundamental studies on SC-CO_(2)fracturing from the aspects of laboratory experiment and simulation are reviewed.The fracturing experimental setups,fracture monitoring and characterizing methods,unconventional formation categories,numerical simulation approaches,fracturing mechanism and field application etc.,are analyzed.The fundamental study results indicate that compared with conventional hydraulic fracturing,SC-CO_(2)fracturing can reduce fracture initiation pressure and easily induce complex fracture networks with multiple branches.The field test further verifies the application prospect and the possibility of carbon storage.However,due to the limitation of reservoir complexity and attributes of SC-CO_(2),massive challenges will be encountered in SC-CO_(2)fracturing.According to the current research status,the limitations in basic research and field application are summarized,and the future development direction of this technology and relevant suggestions are proposed.展开更多
文摘Most of the existing studies on tunnel blast wave are based on spherical or grouped charges,however,conventional weapons are mostly cylindrical rather than spherical.In order to analyze the impact of cylindrical charges on the tunnel blast wave loads and to develop a quantitative calculation method,this study carried out experimental and numerical research.Initially,external explosion experiments were conducted using both 35 kg spherical charges and cylindrical charges with aspect ratio of 4.8 at two different distances from the tunnel entrance.Comparative analysis of the blast wave parameters in the tunnel revealed that the explosive equivalent of the cylindrical charges was significantly higher than that of the spherical charges.To address this,an equivalent coefficient k based on the spherical charges was proposed for the cylindrical charges.Subsequently,numerical simulations were conducted for the experimental conditions,and the numerical simulation results match the experiments well.Through numerical calculations,the reliability of the equivalent coefficient k under the experimental conditions was verified,and comparison analysis indicated that the explosion energy of cylindrical charges spreads more radially,resulting in more explosion energy entering the tunnel,which is the fundamental reason for the increase in tunnel blast wave loads.Additionally,analyzing the explosion energy ratio entering the tunnel is an effective method for calculating the equivalent coefficient k.Finally,through more than one hundred sets of numerical calculation results,the impact of the proportional distance l and the ratio of charge mass to the tunnel cross-section dimension 4 on the equivalence coefficients k was investigated.An empirical formula for the equivalence coefficient k was derived through fitting,and the accuracy of the formula was validated through literature experimental results.The research findings of this paper will provide valuable guidance for the calculation of blast wave loads in tunnel.
基金supported by the Natural Science Foundation of China(Grant Nos.51922107,51874318,51827804and 41961144026)
文摘Under the fact that considerable explo ration and production of unconventional re sources and wo rsening global climate,reducing carbon emission and rationally utilizing carbon resources have been drawn increasing attention.Supercritical CO_(2)(SC-CO_(2)) has been proposed as anhydrous fracturing fluid to develop unconventional reservoirs,since its advantages of reducing water consumption,reservoir contamination etc.Well understanding of SC-CO_(2)fracturing mechanism and key influencing factors will exert significant impact on the application of this technology in the field.In this paper,the fundamental studies on SC-CO_(2)fracturing from the aspects of laboratory experiment and simulation are reviewed.The fracturing experimental setups,fracture monitoring and characterizing methods,unconventional formation categories,numerical simulation approaches,fracturing mechanism and field application etc.,are analyzed.The fundamental study results indicate that compared with conventional hydraulic fracturing,SC-CO_(2)fracturing can reduce fracture initiation pressure and easily induce complex fracture networks with multiple branches.The field test further verifies the application prospect and the possibility of carbon storage.However,due to the limitation of reservoir complexity and attributes of SC-CO_(2),massive challenges will be encountered in SC-CO_(2)fracturing.According to the current research status,the limitations in basic research and field application are summarized,and the future development direction of this technology and relevant suggestions are proposed.
