Water-coupled charge blasting is a promising technique to efficiently break rock masses.In this study,numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by ...Water-coupled charge blasting is a promising technique to efficiently break rock masses.In this study,numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by the tests of rock masses subjected to explosion loads to examine its performance.The crack levels of rock mass induced by water-coupled charge blasting and air-coupled charge blasting are first compared.It is found that water-coupled charge blasting is more appropriate to fracture deep rock mass than air-coupled charge blasting.In addition,the effects of rock properties,water-coupled charge coefficients,and borehole connection angles on the performance of water-coupled charge blasting are investigated.The results show that rock properties and water-coupled charge coefficients can greatly influence the crack and fragmentation levels of rock mass induced by water-coupled charge blasting under uniform and non-uniform in-situ stresses.However,changing borehole-connection angles can only affect crack and fragmentation levels of rock mass under non-uniform in-situ stresses but barely affect those under uniform in-situ stresses.A formula is finally proposed by considering the above-mentioned factors to provide the design suggestion of water-coupled charge blasting to fracture rock mass with different in-situ stresses.展开更多
With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock fragmentation.However,little at...With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock fragmentation.However,little attention has been given to the change in seismic wave radiation when the fractured zone changes with the in-situ stress.In this study,the influences of in-situ stress on blast-induced rock fracture and seismic wave radiation are numerically investigated by a coupled SPH-FEM simulation method.The results show that the change in blast-induced rock fracture with in-situ stress has a considerable effect on the seismic wave energy and composition.As the in-situ stress level increases,the size of the fractured zone is significantly reduced,and more explosion energy is transformed into seismic energy.A reduction in the size of the fractured zone(seismic wave source zone)results in a higher frequency content of the seismic waves.In a nonhydrostatic in-situ stress field,blast-induced cracks are most suppressed in the direction of the minimum in-situ stress,and thus the seismic waves generated in this direction have the highest energy density.In addition to P-waves,Swaves are also generated when a circular explosive is detonated in a nonhydrostatic in-situ stress field.The S-waves result from the asymmetrical release of rock strain energy due to the anisotropic blast-induced fracture pattern.展开更多
The effect of yield-to-tensile strength ratio(Y/T) on failure pressure of X70 pipeline without and with corrosion defects was investigated.The stress-strain response of materials was characterized by a power-law harde...The effect of yield-to-tensile strength ratio(Y/T) on failure pressure of X70 pipeline without and with corrosion defects was investigated.The stress-strain response of materials was characterized by a power-law hardening curve.Two formulas to estimate the strain hardening exponent n for a special Y/T were obtained by least squared regression method and the influence of Y/T on n was analyzed.As an application of n-Y/T expression,the analytical solutions of burst pressure for X70 pipeline without and with corrosion defects were also obtained.The results indicate that the burst pressure of defect-free X70 pipe without corrosion defects is a function of the Y/T,pipe geometry t0/D0 and engineering tensile strength,and increases as Y/T or t0/D0 increases; whilst the burst pressure of corroded X70 pipe decreases with the increase of defect depths,d/t.Comparisons indicate that the present analytical solutions closely match available experimental and numerical data.展开更多
Based on the research on rock burst phenomenon induced by the breakage of thick and hard roof around roadways and working faces in coal mines, a criterion of rock burst induced by roof breakage （RBRB） was proposed a...Based on the research on rock burst phenomenon induced by the breakage of thick and hard roof around roadways and working faces in coal mines, a criterion of rock burst induced by roof breakage （RBRB） was proposed and the model was built. Through the model, a method calculating the varied stresses induced by roof breakage in support objects and coal body was proposed and a unified formula was derived for the calculation of stress increment on support objects and coal body under different breaking forms of roof. Whilst the formula for calculating dynamic load was derived by introducing dynamic index Kd. The formula was verified in Huating Mine by stress measurement. According to the formula for stress increment calculating, the sensitivities of dynamic load parameters were further studied. The results show that the thickness and breaking depth of roof, width of support objeet are the sensitive factors. Based on the discussion of the model, six associated effective methods for rock burst prevention are obtained.展开更多
基金Projects(52334003,52104111,52274249)supported by the National Natural Science Foundation of ChinaProject(2022YFC2903901)supported by the National Key R&D Project of ChinaProject(2024JJ4064)supported by the Natural Science Foundation of Hunan Province,China。
文摘Water-coupled charge blasting is a promising technique to efficiently break rock masses.In this study,numerical models of double boreholes with water-coupled charge are established using LS-DYNA and are calibrated by the tests of rock masses subjected to explosion loads to examine its performance.The crack levels of rock mass induced by water-coupled charge blasting and air-coupled charge blasting are first compared.It is found that water-coupled charge blasting is more appropriate to fracture deep rock mass than air-coupled charge blasting.In addition,the effects of rock properties,water-coupled charge coefficients,and borehole connection angles on the performance of water-coupled charge blasting are investigated.The results show that rock properties and water-coupled charge coefficients can greatly influence the crack and fragmentation levels of rock mass induced by water-coupled charge blasting under uniform and non-uniform in-situ stresses.However,changing borehole-connection angles can only affect crack and fragmentation levels of rock mass under non-uniform in-situ stresses but barely affect those under uniform in-situ stresses.A formula is finally proposed by considering the above-mentioned factors to provide the design suggestion of water-coupled charge blasting to fracture rock mass with different in-situ stresses.
基金Projects(51969015,U1765207)supported by the National Natural Science Foundation of ChinaProjects(20192ACB21019,20181BAB206047)supported by the Natural Science Foundation of Jiangxi Province,China。
文摘With regard to blasting in deep rock masses,it is commonly thought that an increase in the in-situ stress will change the blast-induced rock crack propagation and ultimately affect rock fragmentation.However,little attention has been given to the change in seismic wave radiation when the fractured zone changes with the in-situ stress.In this study,the influences of in-situ stress on blast-induced rock fracture and seismic wave radiation are numerically investigated by a coupled SPH-FEM simulation method.The results show that the change in blast-induced rock fracture with in-situ stress has a considerable effect on the seismic wave energy and composition.As the in-situ stress level increases,the size of the fractured zone is significantly reduced,and more explosion energy is transformed into seismic energy.A reduction in the size of the fractured zone(seismic wave source zone)results in a higher frequency content of the seismic waves.In a nonhydrostatic in-situ stress field,blast-induced cracks are most suppressed in the direction of the minimum in-situ stress,and thus the seismic waves generated in this direction have the highest energy density.In addition to P-waves,Swaves are also generated when a circular explosive is detonated in a nonhydrostatic in-situ stress field.The S-waves result from the asymmetrical release of rock strain energy due to the anisotropic blast-induced fracture pattern.
基金Project(N110607002)supported by the Fundamental Research Funds for the Central Universities of ChinaProject(51074052)supported by the National Natural Science Foundation of China
文摘The effect of yield-to-tensile strength ratio(Y/T) on failure pressure of X70 pipeline without and with corrosion defects was investigated.The stress-strain response of materials was characterized by a power-law hardening curve.Two formulas to estimate the strain hardening exponent n for a special Y/T were obtained by least squared regression method and the influence of Y/T on n was analyzed.As an application of n-Y/T expression,the analytical solutions of burst pressure for X70 pipeline without and with corrosion defects were also obtained.The results indicate that the burst pressure of defect-free X70 pipe without corrosion defects is a function of the Y/T,pipe geometry t0/D0 and engineering tensile strength,and increases as Y/T or t0/D0 increases; whilst the burst pressure of corroded X70 pipe decreases with the increase of defect depths,d/t.Comparisons indicate that the present analytical solutions closely match available experimental and numerical data.
基金Project(2010CB226805) supported by the National Basic Research Program of ChinaProjects(30370412,30670558) supported by the National Natural Science Foundation of ChinaProject(SKLCRSM10X05) supported by the Self-research Program of the Key Laboratory of Coal Resources and Safe Mining,China
文摘Based on the research on rock burst phenomenon induced by the breakage of thick and hard roof around roadways and working faces in coal mines, a criterion of rock burst induced by roof breakage （RBRB） was proposed and the model was built. Through the model, a method calculating the varied stresses induced by roof breakage in support objects and coal body was proposed and a unified formula was derived for the calculation of stress increment on support objects and coal body under different breaking forms of roof. Whilst the formula for calculating dynamic load was derived by introducing dynamic index Kd. The formula was verified in Huating Mine by stress measurement. According to the formula for stress increment calculating, the sensitivities of dynamic load parameters were further studied. The results show that the thickness and breaking depth of roof, width of support objeet are the sensitive factors. Based on the discussion of the model, six associated effective methods for rock burst prevention are obtained.
