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
This study investigated the performances of a new type of precast beam-column joint subjected to earthquake and impact loads.For sustainability and durability considerations,new materials such as corrosion-resistant f...This study investigated the performances of a new type of precast beam-column joint subjected to earthquake and impact loads.For sustainability and durability considerations,new materials such as corrosion-resistant fibre reinforced polymer(FRP)bolts and reinforcements,fibre reinforced concrete(FRC),and geopolymer concrete(GPC)were used to construct the joint.To examine the resilience,durability,sustainability,and multi-hazard resistance capacities,both cyclic and pendulum impact tests were carried out.The experimental results demonstrated that the proposed precast joints had the comparable or even better performances as compared with the traditional monolithic joints under cyclic and impact loads.Numerical simulations using ABAQUS were also adopted to determine the optimal values of the concrete-end-plate(CEP)thickness for the proposed dry joints and to further quantify other response parameters which could not be obtained during the test,e.g.,stress distribution,energy absorption,and stress contours.Discussion on the influences of various parameters on joint performances under different loading conditions was also presented in this study.展开更多
Double-arch tunnels,as one of the popular forms of tunnels,might be exposed to boiling liquid expanding vapour explosions(BLEVEs)associated with transported liquified petroleum gas(LPG),which could cause damage to the...Double-arch tunnels,as one of the popular forms of tunnels,might be exposed to boiling liquid expanding vapour explosions(BLEVEs)associated with transported liquified petroleum gas(LPG),which could cause damage to the tunnel and even catastrophic collapse of the tunnel in extreme cases.However,very limited study has investigated the performance of double-arch tunnels when exposed to internal BLEVEs and in most analyses of tunnel responses to accidental explosions.The TNT-equivalence method was used to approximate the explosion load,which may lead to inaccurate tunnel response predictions.This study numerically investigates the response of typical double-arch tunnels to an internal BLEVE resulting from the instantaneous rupture of a 20 m^(3) LPG tank.Effects of various factors,including in-situ stresses,BLEVE locations,and lining configurations on tunnel responses are examined.The results show that the double-arch tunnels at their early-operation ages are more vulnerable to severe damage when exposed to the BLEVE due to the low action of in-situ stress of rock mass on the response of early-age tunnels.It is also found that directing the LPG tank to different driving lanes inside tunnels can affect the BLEVE-induced tunnel response more significantly than varying the configurations of tunnel lining.Moreover,installing section-steel arches in the mid-wall can effectively improve the blast resistance of the double-arch tunnels against the internal BLEVE.In addition,the prediction models based on multi-variate nonlinear regressions and machine learning methods are developed to predict the BLEVE-induced damage levels of the double-arch tunnels without and with section-steel arches.展开更多
Accidental boiling liquid expansion vapour explosions(BLEVEs)caused by the bursting of liquified petroleum gas(LPG)tank inside a tunnel can induce vibrations of its surrounding geological media and threaten the stabil...Accidental boiling liquid expansion vapour explosions(BLEVEs)caused by the bursting of liquified petroleum gas(LPG)tank inside a tunnel can induce vibrations of its surrounding geological media and threaten the stability of adjacent tunnels and structures.Therefore,it is essential to understand the characteristics of vibrations induced by LPG BLEVEs inside the tunnel for the safety design of its adjacent structures.Owing to the difficulty in effectively predicting the LPG BLEVE loads,the current practice usually employs equivalent methods,e.g.,the TNT-equivalency method,in LPG BLEVE load predictions for structural response analysis,which may lead to inaccurate response predictions.This study compares ground vibrations induced by a BLEVE inside an arched road tunnel with those induced by its equivalent TNT explosion via high-fidelity numerical simulations.The results demonstrate that the frequency of BLEVEinduced vibrations is lower than that induced by the TNT explosion at the same scaled distance.The intensity of LPG BLEVE-induced vibrations at relatively small-scaled distances is lower than that of TNT explosion-induced vibrations at the same scaled distance,but becomes higher after a certain scaled distance because of the relatively low attenuation rate.In addition,parametric analysis is conducted to evaluate the effects of various factors on the characteristics of LPG BLEVE-induced ground vibrations.It is found that the surrounding rock type,the rock porosity,and the cover depth of the tunnel have more significant influences than the concrete grade of the tunnel lining.The recommendation for the tunnel design is also given based on the intensity and frequency characteristics of BLEVE-induced vibrations.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Project(2022YFC2903901)supported by the National Key R&D Project of ChinaProjects(52274249,52334003)supported by the National Natural Science Foundation of China+1 种基金Project(2020-24)supported by the Key Science and Technology Project of Guangxi Transportation Industry,ChinaProject(2023ZZTS0516)supported by the Fundamental Research Funds for the Central Universities,China。
基金financial support from the Australian Research Council Laureate Fellowships FL180100196。
文摘This study investigated the performances of a new type of precast beam-column joint subjected to earthquake and impact loads.For sustainability and durability considerations,new materials such as corrosion-resistant fibre reinforced polymer(FRP)bolts and reinforcements,fibre reinforced concrete(FRC),and geopolymer concrete(GPC)were used to construct the joint.To examine the resilience,durability,sustainability,and multi-hazard resistance capacities,both cyclic and pendulum impact tests were carried out.The experimental results demonstrated that the proposed precast joints had the comparable or even better performances as compared with the traditional monolithic joints under cyclic and impact loads.Numerical simulations using ABAQUS were also adopted to determine the optimal values of the concrete-end-plate(CEP)thickness for the proposed dry joints and to further quantify other response parameters which could not be obtained during the test,e.g.,stress distribution,energy absorption,and stress contours.Discussion on the influences of various parameters on joint performances under different loading conditions was also presented in this study.
基金financial support from the Australian Research Council(ARC)via Australian Laureate Fellowship(FL180100196).
文摘Double-arch tunnels,as one of the popular forms of tunnels,might be exposed to boiling liquid expanding vapour explosions(BLEVEs)associated with transported liquified petroleum gas(LPG),which could cause damage to the tunnel and even catastrophic collapse of the tunnel in extreme cases.However,very limited study has investigated the performance of double-arch tunnels when exposed to internal BLEVEs and in most analyses of tunnel responses to accidental explosions.The TNT-equivalence method was used to approximate the explosion load,which may lead to inaccurate tunnel response predictions.This study numerically investigates the response of typical double-arch tunnels to an internal BLEVE resulting from the instantaneous rupture of a 20 m^(3) LPG tank.Effects of various factors,including in-situ stresses,BLEVE locations,and lining configurations on tunnel responses are examined.The results show that the double-arch tunnels at their early-operation ages are more vulnerable to severe damage when exposed to the BLEVE due to the low action of in-situ stress of rock mass on the response of early-age tunnels.It is also found that directing the LPG tank to different driving lanes inside tunnels can affect the BLEVE-induced tunnel response more significantly than varying the configurations of tunnel lining.Moreover,installing section-steel arches in the mid-wall can effectively improve the blast resistance of the double-arch tunnels against the internal BLEVE.In addition,the prediction models based on multi-variate nonlinear regressions and machine learning methods are developed to predict the BLEVE-induced damage levels of the double-arch tunnels without and with section-steel arches.
文摘Accidental boiling liquid expansion vapour explosions(BLEVEs)caused by the bursting of liquified petroleum gas(LPG)tank inside a tunnel can induce vibrations of its surrounding geological media and threaten the stability of adjacent tunnels and structures.Therefore,it is essential to understand the characteristics of vibrations induced by LPG BLEVEs inside the tunnel for the safety design of its adjacent structures.Owing to the difficulty in effectively predicting the LPG BLEVE loads,the current practice usually employs equivalent methods,e.g.,the TNT-equivalency method,in LPG BLEVE load predictions for structural response analysis,which may lead to inaccurate response predictions.This study compares ground vibrations induced by a BLEVE inside an arched road tunnel with those induced by its equivalent TNT explosion via high-fidelity numerical simulations.The results demonstrate that the frequency of BLEVEinduced vibrations is lower than that induced by the TNT explosion at the same scaled distance.The intensity of LPG BLEVE-induced vibrations at relatively small-scaled distances is lower than that of TNT explosion-induced vibrations at the same scaled distance,but becomes higher after a certain scaled distance because of the relatively low attenuation rate.In addition,parametric analysis is conducted to evaluate the effects of various factors on the characteristics of LPG BLEVE-induced ground vibrations.It is found that the surrounding rock type,the rock porosity,and the cover depth of the tunnel have more significant influences than the concrete grade of the tunnel lining.The recommendation for the tunnel design is also given based on the intensity and frequency characteristics of BLEVE-induced vibrations.
