Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at ...Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.展开更多
The Rock-soil interface is a common geological interface.Due to mechanical differences between soil and rock,the stress waves generated by underground blasting undergo intense polarization when crossing the rock-soil ...The Rock-soil interface is a common geological interface.Due to mechanical differences between soil and rock,the stress waves generated by underground blasting undergo intense polarization when crossing the rock-soil interface,making propagation laws difficult to predict.Currently,the characteristics of the impact of the rock-soil interface on blasting stress waves remain unclear.Therefore,the vibration field caused by cylindrical charge blasting in elastic rock and partial-saturation poro-viscoelastic soil was solved.A forward algorithm for the underground blasting vibration field in rock-soil sites was proposed,considering medium damping and geometric diffusion effects of stress waves.Further investigation into the influence of rock and soil parameters and blasting source parameters revealed the following conclusions:stress waves in soil exhibit dispersion,causing peak particle velocity(PPV)to display a discrete distribution.Soil parameters affect PPV attenuation only within the soil,while blasting source parameters affect PPV attenuation throughout the entire site.Multi-wave coupling effects induced by the rocksoil interface result in zones of enhanced and attenuated PPV within the site.The size of the enhancement zone is inversely correlated with the distance from the blasting source and positively correlated with the blasting source attenuation rate and burial depth,providing guidance for selecting explosives and blasting positions.Additionally,PPV attenuation rate increases with distance from the rock-soil interface,but an amplification effect occurs near the interface,most noticeable at 0.1 m.Thus,a sufficient safety distance from the rock-soil interface is necessary during underground blasting.展开更多
The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium...The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium,without considering the wave attenuation caused by viscoelasticity and wave separation induced by rock discontinuities,as well as plane waves while neglecting geometric attenuation of near-field nonplane blast waves.This paper establishes a theoretical model of cylindrical P-wave propagation across a fault to an adjacent existing tunnel.Based on the time-domain recursive method,vibration equations and peak particle velocity on the adjacent existing tunnel wall caused by a cylindrical wave passing through a fault are derived.The rock mass and fault are assumed to satisfy Kelvin viscoelastic bodies,and contact interfaces between fault and rock mass follow a nonlinear hyperbolic deformation model in the normal direction and a linear model in the tangential direction.The results show that tunnel vibration caused by the blast cylindrical P-wave is primarily induced by transmitted P-waves.With the increase of the fault dip angle,vibration on the upper side of the adjacent existing tunnel gradually decreases,while vibration on the lower side increases.The closer the vibration to the upper and lower sides,the stronger the shear effect on the tunnel wall,and the closer the vibration to the middle,the stronger the pressure effect on the tunnel wall.Larger fault thickness and higher initial blast wave frequency result in weaker vibration of the adjacent tunnel.The deeper the burial depth,the stronger the vibration of the adjacent tunnel wall.Findings of this study provide insight into the dynamic response of rock construction and safety evaluation in engineering service.展开更多
Drilling and blasting in layered rock masses faces significant challenges,as pre-existing joints cause unbalanced energy distribution,leading to poor forming effects and severe over-excavation.However,a comprehensive ...Drilling and blasting in layered rock masses faces significant challenges,as pre-existing joints cause unbalanced energy distribution,leading to poor forming effects and severe over-excavation.However,a comprehensive understanding of the complex coupling mechanisms between key joint parameters and the in-situ stress field on the final blasting outcome is still lacking.The model tests are used to quantitatively analyze the macroscopic crushing characteristics and crack propagation velocity.The numerical simulation then reveals the underlying mechanisms of stress wave propagation and energy partitioning,which are validated against the experimental results.The results indicate that the joints and the in-situ stress field play distinct,competitive roles in the blasting outcome.First,the joints control the anisotropy of the damage:crack propagation is primarily guided along the joint direction(the channel effect),and the apparent crack velocity exhibits a V-shaped trend with the joint inclination angle(0°-90°).Second,the in-situ stress state controls the overall extent of the damage:Increased confining pressure(both equal and unequal)inhibits crack propagation by increasing the failure threshold of the rock mass.Mechanistically,while this locking effect enhances stress wave transmission(i.e.,reduces the locking effect),this is secondary to the dominant inhibitory effect of the increased overall rock mass strength.The primary contribution of this study is the identification of this dual control mechanism,revealing that the final blasting effect is a non-linear competition between the joint's structural guidance and the dominant strengthening effect from the in-situ stress field,which clarifies the complex energy partitioning mechanisms at the blast source.展开更多
The propagation characteristics of the amplitude of the blasting seismic wave under the conditions of various topographies are approached by means of experiments. Some factors affecting the effects of quake insulation...The propagation characteristics of the amplitude of the blasting seismic wave under the conditions of various topographies are approached by means of experiments. Some factors affecting the effects of quake insulation groove, such as the size, the depth and the position of the quake insulation groove, are studied. The amplitudes of the blasting seismic waves under the conditions of the different sizes of the quake insulation groove are measured. According to the experiments, the effects of the quake insulation groove are related to the position, the distance, the energy of the explosion source and the size of the quake insulation groove itself. The farther it is from the explosion source, the smaller the energy is. The lower its position is and the larger its size is, the more remarkable the effects of the quake insulation groove are.展开更多
With the application of electronic detonators, millisecond blasting is regarded as a signifi cant promising approach to improve the rock fragmentation in deep rock blasting. Thus, it is necessary to investigate the fr...With the application of electronic detonators, millisecond blasting is regarded as a signifi cant promising approach to improve the rock fragmentation in deep rock blasting. Thus, it is necessary to investigate the fracturing mechanisms of short-delay blasting. In this work, a rectangle model with two circle boreholes is modeled as a particles assembly based on the discrete element method to simulate the shock wave interactions induced by millisecond blasting. The rectangle model has a size of 12 × 6 m (L × W) and two blast holes have the same diameter of 12 cm. The shock waves are simplifi ed as time-varying forces applied at the particles of walls of the two boreholes. Among a series of numerical tests in this study, the spacing between two adjacent boreholes and delay time of millisecond blasting are considered as two primary variables, and the decoupling charge with a coeffi cient of 1.5 is taken into account in each case. The results show that stress superposition is not a key factor for improving rock fragmentation (tensile stress interactions rather than compressive stress superposition could aff ect the generation of cracks), whereas collision actions from isolated particles or particles with weakened constraints play a crucial role in creating the fracture network. The delay time has an infl uence on causing cracks in rock blasting, however, whether it works heavily depends on the distance between the two holes.展开更多
Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the nu...Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the numerical results are sensitive to the finite element mesh size.Previous numerical simulations show that a mesh size acceptable to one blast scenario might not be proper for another case,even though the difference between the two scenarios is very small,indicating a simple numerical mesh size convergence test might not be enough to guarantee accu-rate numerical results.Therefore,both coarse mesh and fine mesh were used in different blast scenarios to investigate the mesh size effect on numerical results of blast wave propagation and interaction with structures.Based on the numerical results and their comparison with field test re-sults and the design charts in TM5-1300,a numerical modification method was proposed to correct the influence of the mesh size on the simulated results.It can be easily used to improve the accu-racy of the numerical results of blast wave propagation and blast loads on structures.展开更多
The effect of blasting vibration waves on surrounding rock and supporting structures is an important field in underground engineering. In this paper, the separation variable method is used to solve the displacement po...The effect of blasting vibration waves on surrounding rock and supporting structures is an important field in underground engineering. In this paper, the separation variable method is used to solve the displacement potential function for the propagation of the blasting vibration waves. In the axis coordinate system, the particle motion and stress change with axial distance, radial distance and time is obtained in surrounding rock. The peak particle velocity law in surrounding rock under different blast loads and surrounding rock parameters is discussed.In addition, the particle vibration characteristics in the surrounding rock are studied using numerical simulations method. The results shows that the peak particle velocity in surrounding rock appears negative exponent attenuation with the increase of axial distance, but it appears positive and negative fluctuations in radial direction. This phenomenon is a new discovery and it has been rarely investigated before. Moreover, the peak particle velocity attenuates more quickly and intensely in the near blasting field,which means that the supporting structure in a shorter distance away from the heading face is vulnerable to the impact of blasting vibration. Theattenuation of blasting vibration velocity is closely related to charge length, blasting load amplitude,attenuation index and rock elastic modulus. The numerical simulation accomplishes the same results and then demonstrates the validity of theoretical results.展开更多
The numerical simulation of a blast wave of a multilayer composite charge is investigated.A calculation model of the near-field explosion and far-field propagation of the shock wave of a composite charge is establishe...The numerical simulation of a blast wave of a multilayer composite charge is investigated.A calculation model of the near-field explosion and far-field propagation of the shock wave of a composite charge is established using the AUTODYN finite element program.Results of the near-field and far-field calculations of the shock wave respectively converge at cell sizes of 0.25-0.5 cm and 1-3 cm.The Euler--fluxcorrected transport solver is found to be suitable for the far-field calculation after mapping.A numerical simulation is conducted to study the formation,propagation,and interaction of the shock wave of the composite charge for different initiation modes.It is found that the initiation mode obviously affects the shock-wave waveform and pressure distribution of the composite charge.Additionally,it is found that the area of the overpressure distribution is greatest for internal and external simultaneous initiation,and the peak pressure of the shock wave exponentially decays,fitting the calculation formula of the peak overpressure attenuation under different initiation modes,which is obtained and verified by experiment.The difference between numerical and experimental results is less than 10%,and the peak overpressure of both internal and external initiation is 56.12% higher than that of central single-point initiation.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
This paper presents the explosion cratering effects and their propagation laws of blast waves in dry standard sands using a 450 g-t geotechnical centrifuge apparatus.Ten centrifuge model tests were completed with vari...This paper presents the explosion cratering effects and their propagation laws of blast waves in dry standard sands using a 450 g-t geotechnical centrifuge apparatus.Ten centrifuge model tests were completed with various ranges of explosive mass,burial depth and centrifuge accelerations.Eleven accelerometers were installed to record the acceleration response in sand.The dimensions of the explosion craters were measured after the tests.The results demonstrated that the relationship between the dimensionless parameters of cratering efficiency and gravity scaled yield is a power regression function.Three specific function equations were obtained.The results are in general agreement with those obtained by other studies.A scaling law based on the combination of the π terms was used to fit the results of the ten model tests with a correlation coefficient of 0.931.The relationship can be conveniently used to predict the cratering effects in sand.The results also showed that the peak acceleration is a power increasing function of the acceleration level.An empirical exponent relation between the proportional peak acceleration and distance is proposed.The propagation velocity of blast waves is found to be ranged between 200 and 714 m/s.展开更多
Among the intrinsic properties of some materials,e.g.,foams,porous materials,and granular materials,are their ability to mitigate shock waves.This paper investigated shock wave mitigation by a sandwich panel with a gr...Among the intrinsic properties of some materials,e.g.,foams,porous materials,and granular materials,are their ability to mitigate shock waves.This paper investigated shock wave mitigation by a sandwich panel with a granular core.Numerical simulations and experimental tests were performed using Autodyn hydro-code software and a shock tube,respectively.The smoothed particle hydrodynamics(SPH)method was used to model granular materials.Sawdust and pumice,whose properties were determined by several compression tests,were used as granular materials in the sandwich panel core.These granular materials possess many mechanisms,including compacting(e.g.,sawdust)and crushing(e.g.,pumice)that mitigate shock/blast wave.The results indicated the ineffectiveness of using a core with low thickness,yet it was demonstrated to be effective with high thickness.Low-thickness pumice yielded better results for wave mitigation.The use of these materials with a core with appropriate core reduces up to 88%of the shock wave.The results of the experiments and numerical simulations were compared,suggesting a good agreement between the two.This indicates the accuracy of simulation and the ability of the SPH method to modeling granular material under shock loading.The effects of grain size and the coefficient of friction between grains have also been investigated using simulation,implying that increasing the grain size and coefficient of friction between grains both reduce overpressure.展开更多
Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Aus...Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Australia,by using spread velocities,amplitudes and frequency contents as the main analysis parameters.The results show that the average P-wave velocity,mean values of combined maximal amplitudes and frequencies of the first arrivals are all reduced significantly along with goaf expanding and intensity weakening of overlying strata during mining process.A full roof fracturing can make the average P-wave velocities,combined maximal amplitudes and frequencies of first arrivals reduce to about 69.8%,92.2% and 60.0%,respectively.The reduction of the above seismic parameters reveals dynamic effects of the variation of strata structure and property to the wave transmission and energy dissipation of blasting wave.The research greatly benefits further study on stability of surrounding rock under the destructive effort by mine tremor,blasting,etc,and provides experimental basis for source relocation and parameter optimization of seismic monitoring as well.展开更多
Objective To observe the dynamic impacts of shock waves on the severity of lung injury in rats with different injury distances.Methods Simulate open-field shock waves;detect the biomechanical effects of explosion sour...Objective To observe the dynamic impacts of shock waves on the severity of lung injury in rats with different injury distances.Methods Simulate open-field shock waves;detect the biomechanical effects of explosion sources at distances of 40,44,and 48 cm from rats;and examine the changes in the gross anatomy of the lungs,lung wet/dry weight ratio,hemoglobin concentration,blood gas analysis,and pathology.Results Biomechanical parameters such as the overpressure peak and impulse were gradually attenuated with an increase in the injury distance.The lung tissue hemorrhage,edema,oxygenation index,and pathology changed more significantly for the 40 cm group than for the 44 and 48 cm groups.The overpressure peak and impulse were significantly higher for the 40 cm group than for the 44 and 48 cm groups(P<0.05 or P<0.01).The animal mortality was significantly higher for the 40 cm group than for the other two groups(41.2%vs.17.8%and 10.0%,P<0.05).The healing time of injured lung tissues for the 40 cm group was longer than those for the 44 and 48 cm groups.Conclusions The effects of simulated open-field shock waves on the severity of lung injuries in rats were correlated with the injury distances,the peak overpressure,and the overpressure impulse.展开更多
A typical blasting vibration wave is a composite wave,and its attenuation law is affected by the type of dominant wave component.The purpose of the present study is to establish an attenuation equation of the peak par...A typical blasting vibration wave is a composite wave,and its attenuation law is affected by the type of dominant wave component.The purpose of the present study is to establish an attenuation equation of the peak particle velocity(PPV),taking into account the attenuation characteristics of P-,S-and R-waves in the blasting vibration wave.Field blasting tests were carried out as a case to specifically apply the proposed equation.In view of the fact that the discrete properties of rock mass will inevitably cause the uncertainty of blasting vibration,we also carried out a probability analysis of PPV uncertainty,and introduced the concept of reliability to evaluate blasting vibration.The results showed that the established attenuation equation had a higher prediction accuracy,and can be considered as a promising equation implemented on more complex sites.The adopted uncertainty analysis method can comprehensively take account of the attenuation law of blasting vibration measured on site and discrete properties of rock masses.The obtained distribution of the PPV uncertainty factor can quantitatively evaluate the reliability of blasting vibration,which is a powerful and necessary supplement to the PPV attenuation equation.展开更多
The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparat...The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparatus. The blasting test was carried out for ten times at some tunnels of Changba Lead-Zinc Mine. The damage depth of surrounding rock caused by old blasting excavation （0.8-1.2 m） was confirmed. The relation between the cumulative damage degree and blast times was obtained. The results show that the sonic velocity decreases gradually with increasing blast times, hut the damage degree （D） increases. The damage cumulative law is non-linear. The damage degree caused by blast decreases with increasing distance, and damage effects become indistinct. The blasting damage of rock mass is anisotropic. The damage degree of rock mass within charging range is maximal. And the more the charge is, the more severe the damage degree of rock mass is. The test results provide references for researches of mechanical parameters of rock mass and dynamic stability analysis of underground chambers.展开更多
The explosion inside tunnel would generate blast wave which transmits through the longitudinal tunnel. Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure, blast wave pro...The explosion inside tunnel would generate blast wave which transmits through the longitudinal tunnel. Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure, blast wave propagation inside tunnel is distinguished from that in air. When the explosion happens inside tunnel, the overpressure peak is higher than that of explosion happening in air. The continuance time of the blast wave also becomes longer. With the help of the numerical simulation finite element software LS-DYNA, a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out. LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems. Compared with the experimental results, the simulation results have made the material parameters of numerical simulation model available. By using the model and the same material parameters, many results were adopted by calculating the model under different TNT explosion dynamites. Then the method of dimensional analysis was used for the simulation results. As overpressures of the explosion blast wave are the governing factor in the tunnel responses, a formula for the explosion blast wave over-pressure at a certain distance from the detonation center point inside the tunnel was derived by using the dimensional analysis theory. By comparing the results computed by the formula with experimental results which were obtained before, the formula was proved to be very applicable at some instance. The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.展开更多
Maximum charge per delay in a blasting round is universally accepted as the influencing parameter to quantify magni-tude of vibration for any distance of concern. However, for any blasting round experimental data reve...Maximum charge per delay in a blasting round is universally accepted as the influencing parameter to quantify magni-tude of vibration for any distance of concern. However, for any blasting round experimental data reveals that for same charge per delay magnitude of vibration varies with total charge. Considering linear transmission of blast waves, the paper firstly investigates into the influence of explosive weight, blast design parameters and geology of strata on magnitude and characteristics of vibration parameters and thereafter communicates that possibly interference of blast waves generated from same and different holes of a blasting round result into variation in vibration magnitude. The paper lastly developed a mathematical model to evaluate points of interference of blast waves generated from single- and multi-hole blasting round.展开更多
All underwater drilling and blasting operations generate seismic waves.However,due to a lack of suitable vibration sensing instruments,most studies on the propagation of seismic waves have been limited to shorelines n...All underwater drilling and blasting operations generate seismic waves.However,due to a lack of suitable vibration sensing instruments,most studies on the propagation of seismic waves have been limited to shorelines near construction areas or wharfs,whereas comparatively few studies have beerconducted on the larger seafloor itself.To address this gap,a seafloor vibration sensor system was developed and applied in this study that consists of an autonomous acquisition storage terminal,soft-ware platform,and hole-plugging device that was designed to record the blasting vibration intensities received through submarine rocks at a given measurement point.Additionally,dimensional analyses were used to derive a predictive equation for the strength of blast vibrations that considered the in fluence of the water depth.By combining reliable vibration data obtained using the sensor system in submarine rock and the developed predictive equation,it was determined that the water depth was ar important factor influencing the measured vibration strength.The results using the newly derivedequation were compared to those determined using the Sadowski equation,which is commonly used on land,and it was found that predictions using the derived equation were closer to the experimental values with an average error of less than 10%,representing a significant improvement.Based on these results the developed sensor system and preliminary theoretical basis was deemed suitable for studying the propagation behavior of submarine seismic waves generated by underwater drilling and blasting operations.展开更多
Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in diff...Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.展开更多
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52422807).
文摘Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.
基金supported by the National Natural Science Foundation of China(Grant Nos.41972286 and 42102329).
文摘The Rock-soil interface is a common geological interface.Due to mechanical differences between soil and rock,the stress waves generated by underground blasting undergo intense polarization when crossing the rock-soil interface,making propagation laws difficult to predict.Currently,the characteristics of the impact of the rock-soil interface on blasting stress waves remain unclear.Therefore,the vibration field caused by cylindrical charge blasting in elastic rock and partial-saturation poro-viscoelastic soil was solved.A forward algorithm for the underground blasting vibration field in rock-soil sites was proposed,considering medium damping and geometric diffusion effects of stress waves.Further investigation into the influence of rock and soil parameters and blasting source parameters revealed the following conclusions:stress waves in soil exhibit dispersion,causing peak particle velocity(PPV)to display a discrete distribution.Soil parameters affect PPV attenuation only within the soil,while blasting source parameters affect PPV attenuation throughout the entire site.Multi-wave coupling effects induced by the rocksoil interface result in zones of enhanced and attenuated PPV within the site.The size of the enhancement zone is inversely correlated with the distance from the blasting source and positively correlated with the blasting source attenuation rate and burial depth,providing guidance for selecting explosives and blasting positions.Additionally,PPV attenuation rate increases with distance from the rock-soil interface,but an amplification effect occurs near the interface,most noticeable at 0.1 m.Thus,a sufficient safety distance from the rock-soil interface is necessary during underground blasting.
基金Natural Science Basic Research Program of Shaanxi Province,Grant/Award Number:2023-YBGY-085National Natural Science Foundation of China,Grant/Award Numbers:41902277,42172302Fundamental Research Funds for the Central Universities,Grant/Award Number:CHD.300102282201。
文摘The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium,without considering the wave attenuation caused by viscoelasticity and wave separation induced by rock discontinuities,as well as plane waves while neglecting geometric attenuation of near-field nonplane blast waves.This paper establishes a theoretical model of cylindrical P-wave propagation across a fault to an adjacent existing tunnel.Based on the time-domain recursive method,vibration equations and peak particle velocity on the adjacent existing tunnel wall caused by a cylindrical wave passing through a fault are derived.The rock mass and fault are assumed to satisfy Kelvin viscoelastic bodies,and contact interfaces between fault and rock mass follow a nonlinear hyperbolic deformation model in the normal direction and a linear model in the tangential direction.The results show that tunnel vibration caused by the blast cylindrical P-wave is primarily induced by transmitted P-waves.With the increase of the fault dip angle,vibration on the upper side of the adjacent existing tunnel gradually decreases,while vibration on the lower side increases.The closer the vibration to the upper and lower sides,the stronger the shear effect on the tunnel wall,and the closer the vibration to the middle,the stronger the pressure effect on the tunnel wall.Larger fault thickness and higher initial blast wave frequency result in weaker vibration of the adjacent tunnel.The deeper the burial depth,the stronger the vibration of the adjacent tunnel wall.Findings of this study provide insight into the dynamic response of rock construction and safety evaluation in engineering service.
基金supported by funding from the National Natural Science Foundation of China(42372331,52204140)State key Laboratory of Mining Disaster Prevention and Control(Shandong University of Science and Technology)(JMDPC202302)+2 种基金the high-level talent cultivation funding program for the"Double First-Class"initiative in safety discipline at Henan Polytechnic University(AQ20250205)the Taishan Scholar Program of Shandong Province(tsqnz20240825)Open Fund of Shandong Engineering Research Center for Mine Gas Disaster Prevention and Control(No.2022-005)。
文摘Drilling and blasting in layered rock masses faces significant challenges,as pre-existing joints cause unbalanced energy distribution,leading to poor forming effects and severe over-excavation.However,a comprehensive understanding of the complex coupling mechanisms between key joint parameters and the in-situ stress field on the final blasting outcome is still lacking.The model tests are used to quantitatively analyze the macroscopic crushing characteristics and crack propagation velocity.The numerical simulation then reveals the underlying mechanisms of stress wave propagation and energy partitioning,which are validated against the experimental results.The results indicate that the joints and the in-situ stress field play distinct,competitive roles in the blasting outcome.First,the joints control the anisotropy of the damage:crack propagation is primarily guided along the joint direction(the channel effect),and the apparent crack velocity exhibits a V-shaped trend with the joint inclination angle(0°-90°).Second,the in-situ stress state controls the overall extent of the damage:Increased confining pressure(both equal and unequal)inhibits crack propagation by increasing the failure threshold of the rock mass.Mechanistically,while this locking effect enhances stress wave transmission(i.e.,reduces the locking effect),this is secondary to the dominant inhibitory effect of the increased overall rock mass strength.The primary contribution of this study is the identification of this dual control mechanism,revealing that the final blasting effect is a non-linear competition between the joint's structural guidance and the dominant strengthening effect from the in-situ stress field,which clarifies the complex energy partitioning mechanisms at the blast source.
文摘The propagation characteristics of the amplitude of the blasting seismic wave under the conditions of various topographies are approached by means of experiments. Some factors affecting the effects of quake insulation groove, such as the size, the depth and the position of the quake insulation groove, are studied. The amplitudes of the blasting seismic waves under the conditions of the different sizes of the quake insulation groove are measured. According to the experiments, the effects of the quake insulation groove are related to the position, the distance, the energy of the explosion source and the size of the quake insulation groove itself. The farther it is from the explosion source, the smaller the energy is. The lower its position is and the larger its size is, the more remarkable the effects of the quake insulation groove are.
基金National Science Foundation for Young Scientists of China under Grant No.51709176National Natural Science Foundation of China under Grant No.51979170+2 种基金Key Project of Hebei Natural Science Foundation under Grant No.F2019210243Hebei Province Science Foundation for Young Scientists under Grant No.E2018210046Open Project of State Key Laboratory of Advanced Electromagnetic Engineering and Technology under Grant No.AEET 2019KF005
文摘With the application of electronic detonators, millisecond blasting is regarded as a signifi cant promising approach to improve the rock fragmentation in deep rock blasting. Thus, it is necessary to investigate the fracturing mechanisms of short-delay blasting. In this work, a rectangle model with two circle boreholes is modeled as a particles assembly based on the discrete element method to simulate the shock wave interactions induced by millisecond blasting. The rectangle model has a size of 12 × 6 m (L × W) and two blast holes have the same diameter of 12 cm. The shock waves are simplifi ed as time-varying forces applied at the particles of walls of the two boreholes. Among a series of numerical tests in this study, the spacing between two adjacent boreholes and delay time of millisecond blasting are considered as two primary variables, and the decoupling charge with a coeffi cient of 1.5 is taken into account in each case. The results show that stress superposition is not a key factor for improving rock fragmentation (tensile stress interactions rather than compressive stress superposition could aff ect the generation of cracks), whereas collision actions from isolated particles or particles with weakened constraints play a crucial role in creating the fracture network. The delay time has an infl uence on causing cracks in rock blasting, however, whether it works heavily depends on the distance between the two holes.
基金Supported by National Natural Science Foundation of China (No.50638030, 50528808)the National Key Technologies R&D Program of China (No.2006BAJ13B02)the Australian Research Council (No.DP0774061).
文摘Numerical method is popular in analysing the blast wave propagation and interaction with structures.However,because of the extremely short duration of blast wave and energy trans-mission between different grids,the numerical results are sensitive to the finite element mesh size.Previous numerical simulations show that a mesh size acceptable to one blast scenario might not be proper for another case,even though the difference between the two scenarios is very small,indicating a simple numerical mesh size convergence test might not be enough to guarantee accu-rate numerical results.Therefore,both coarse mesh and fine mesh were used in different blast scenarios to investigate the mesh size effect on numerical results of blast wave propagation and interaction with structures.Based on the numerical results and their comparison with field test re-sults and the design charts in TM5-1300,a numerical modification method was proposed to correct the influence of the mesh size on the simulated results.It can be easily used to improve the accu-racy of the numerical results of blast wave propagation and blast loads on structures.
基金supported by the National Nature Science Foundation of China(11672112)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20113718110002)+1 种基金the Fund of the State KeyLaboratory of Disaster Prevention&Mitigation of Explosion&Impact(PLA University and Technology)(DPMEIKF201307)Huaqiao University Research Foundation(13BS402)
文摘The effect of blasting vibration waves on surrounding rock and supporting structures is an important field in underground engineering. In this paper, the separation variable method is used to solve the displacement potential function for the propagation of the blasting vibration waves. In the axis coordinate system, the particle motion and stress change with axial distance, radial distance and time is obtained in surrounding rock. The peak particle velocity law in surrounding rock under different blast loads and surrounding rock parameters is discussed.In addition, the particle vibration characteristics in the surrounding rock are studied using numerical simulations method. The results shows that the peak particle velocity in surrounding rock appears negative exponent attenuation with the increase of axial distance, but it appears positive and negative fluctuations in radial direction. This phenomenon is a new discovery and it has been rarely investigated before. Moreover, the peak particle velocity attenuates more quickly and intensely in the near blasting field,which means that the supporting structure in a shorter distance away from the heading face is vulnerable to the impact of blasting vibration. Theattenuation of blasting vibration velocity is closely related to charge length, blasting load amplitude,attenuation index and rock elastic modulus. The numerical simulation accomplishes the same results and then demonstrates the validity of theoretical results.
基金funded by the National Natural Science Foundation of China under NO.11202103Qing-lan Project of Jiangsu Province。
文摘The numerical simulation of a blast wave of a multilayer composite charge is investigated.A calculation model of the near-field explosion and far-field propagation of the shock wave of a composite charge is established using the AUTODYN finite element program.Results of the near-field and far-field calculations of the shock wave respectively converge at cell sizes of 0.25-0.5 cm and 1-3 cm.The Euler--fluxcorrected transport solver is found to be suitable for the far-field calculation after mapping.A numerical simulation is conducted to study the formation,propagation,and interaction of the shock wave of the composite charge for different initiation modes.It is found that the initiation mode obviously affects the shock-wave waveform and pressure distribution of the composite charge.Additionally,it is found that the area of the overpressure distribution is greatest for internal and external simultaneous initiation,and the peak pressure of the shock wave exponentially decays,fitting the calculation formula of the peak overpressure attenuation under different initiation modes,which is obtained and verified by experiment.The difference between numerical and experimental results is less than 10%,and the peak overpressure of both internal and external initiation is 56.12% higher than that of central single-point initiation.
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supported by the National Natural Science Foundation of China (No. 50779073)the Program Foundation of the China Institute of Water Resources and Hydropower Research (IWHR)(No. YANJI ZD0710)
文摘This paper presents the explosion cratering effects and their propagation laws of blast waves in dry standard sands using a 450 g-t geotechnical centrifuge apparatus.Ten centrifuge model tests were completed with various ranges of explosive mass,burial depth and centrifuge accelerations.Eleven accelerometers were installed to record the acceleration response in sand.The dimensions of the explosion craters were measured after the tests.The results demonstrated that the relationship between the dimensionless parameters of cratering efficiency and gravity scaled yield is a power regression function.Three specific function equations were obtained.The results are in general agreement with those obtained by other studies.A scaling law based on the combination of the π terms was used to fit the results of the ten model tests with a correlation coefficient of 0.931.The relationship can be conveniently used to predict the cratering effects in sand.The results also showed that the peak acceleration is a power increasing function of the acceleration level.An empirical exponent relation between the proportional peak acceleration and distance is proposed.The propagation velocity of blast waves is found to be ranged between 200 and 714 m/s.
文摘Among the intrinsic properties of some materials,e.g.,foams,porous materials,and granular materials,are their ability to mitigate shock waves.This paper investigated shock wave mitigation by a sandwich panel with a granular core.Numerical simulations and experimental tests were performed using Autodyn hydro-code software and a shock tube,respectively.The smoothed particle hydrodynamics(SPH)method was used to model granular materials.Sawdust and pumice,whose properties were determined by several compression tests,were used as granular materials in the sandwich panel core.These granular materials possess many mechanisms,including compacting(e.g.,sawdust)and crushing(e.g.,pumice)that mitigate shock/blast wave.The results indicated the ineffectiveness of using a core with low thickness,yet it was demonstrated to be effective with high thickness.Low-thickness pumice yielded better results for wave mitigation.The use of these materials with a core with appropriate core reduces up to 88%of the shock wave.The results of the experiments and numerical simulations were compared,suggesting a good agreement between the two.This indicates the accuracy of simulation and the ability of the SPH method to modeling granular material under shock loading.The effects of grain size and the coefficient of friction between grains have also been investigated using simulation,implying that increasing the grain size and coefficient of friction between grains both reduce overpressure.
基金Foundation item: Project(2010CB226805) supported by the National Basic Research Program of ChinaProject(2010QNA30) supported by the Fundamental Research Funds for the Central Universities of China+1 种基金Project supported by the Priority Academic Development Program of Jiangsu Higher Education,ChinaProjects(SZBF2011-6-B35,2012BAK04B06) supported by the National Twelfth Five-year Key Science & Technology Foundation of China
文摘Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Australia,by using spread velocities,amplitudes and frequency contents as the main analysis parameters.The results show that the average P-wave velocity,mean values of combined maximal amplitudes and frequencies of the first arrivals are all reduced significantly along with goaf expanding and intensity weakening of overlying strata during mining process.A full roof fracturing can make the average P-wave velocities,combined maximal amplitudes and frequencies of first arrivals reduce to about 69.8%,92.2% and 60.0%,respectively.The reduction of the above seismic parameters reveals dynamic effects of the variation of strata structure and property to the wave transmission and energy dissipation of blasting wave.The research greatly benefits further study on stability of surrounding rock under the destructive effort by mine tremor,blasting,etc,and provides experimental basis for source relocation and parameter optimization of seismic monitoring as well.
基金supported by the Major Project of Military Logistical Support Department[grant number AWS15J003and ALB19J001]。
文摘Objective To observe the dynamic impacts of shock waves on the severity of lung injury in rats with different injury distances.Methods Simulate open-field shock waves;detect the biomechanical effects of explosion sources at distances of 40,44,and 48 cm from rats;and examine the changes in the gross anatomy of the lungs,lung wet/dry weight ratio,hemoglobin concentration,blood gas analysis,and pathology.Results Biomechanical parameters such as the overpressure peak and impulse were gradually attenuated with an increase in the injury distance.The lung tissue hemorrhage,edema,oxygenation index,and pathology changed more significantly for the 40 cm group than for the 44 and 48 cm groups.The overpressure peak and impulse were significantly higher for the 40 cm group than for the 44 and 48 cm groups(P<0.05 or P<0.01).The animal mortality was significantly higher for the 40 cm group than for the other two groups(41.2%vs.17.8%and 10.0%,P<0.05).The healing time of injured lung tissues for the 40 cm group was longer than those for the 44 and 48 cm groups.Conclusions The effects of simulated open-field shock waves on the severity of lung injuries in rats were correlated with the injury distances,the peak overpressure,and the overpressure impulse.
基金financially supported by National Key R&D Program of China(Grant No.2020YFA0711802)National Nature Science Foundation of China(Grant Nos.51439008 and 51779248).
文摘A typical blasting vibration wave is a composite wave,and its attenuation law is affected by the type of dominant wave component.The purpose of the present study is to establish an attenuation equation of the peak particle velocity(PPV),taking into account the attenuation characteristics of P-,S-and R-waves in the blasting vibration wave.Field blasting tests were carried out as a case to specifically apply the proposed equation.In view of the fact that the discrete properties of rock mass will inevitably cause the uncertainty of blasting vibration,we also carried out a probability analysis of PPV uncertainty,and introduced the concept of reliability to evaluate blasting vibration.The results showed that the established attenuation equation had a higher prediction accuracy,and can be considered as a promising equation implemented on more complex sites.The adopted uncertainty analysis method can comprehensively take account of the attenuation law of blasting vibration measured on site and discrete properties of rock masses.The obtained distribution of the PPV uncertainty factor can quantitatively evaluate the reliability of blasting vibration,which is a powerful and necessary supplement to the PPV attenuation equation.
基金Project (50490272) supported by the National Natural Science Foundation of ChinaProject(040109) supported by the Doctor Degree Paper Innovation Engineering of Central South University
文摘The principle of sonic wave measurement was introduced, and cumulative damage effects of underground engineering rock mass under blasting load were studied by in situ test, using RSM-SY5 intelligent sonic wave apparatus. The blasting test was carried out for ten times at some tunnels of Changba Lead-Zinc Mine. The damage depth of surrounding rock caused by old blasting excavation （0.8-1.2 m） was confirmed. The relation between the cumulative damage degree and blast times was obtained. The results show that the sonic velocity decreases gradually with increasing blast times, hut the damage degree （D） increases. The damage cumulative law is non-linear. The damage degree caused by blast decreases with increasing distance, and damage effects become indistinct. The blasting damage of rock mass is anisotropic. The damage degree of rock mass within charging range is maximal. And the more the charge is, the more severe the damage degree of rock mass is. The test results provide references for researches of mechanical parameters of rock mass and dynamic stability analysis of underground chambers.
基金Supported by National Natural Science Foundation of China(No.50678094)
文摘The explosion inside tunnel would generate blast wave which transmits through the longitudinal tunnel. Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure, blast wave propagation inside tunnel is distinguished from that in air. When the explosion happens inside tunnel, the overpressure peak is higher than that of explosion happening in air. The continuance time of the blast wave also becomes longer. With the help of the numerical simulation finite element software LS-DYNA, a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out. LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems. Compared with the experimental results, the simulation results have made the material parameters of numerical simulation model available. By using the model and the same material parameters, many results were adopted by calculating the model under different TNT explosion dynamites. Then the method of dimensional analysis was used for the simulation results. As overpressures of the explosion blast wave are the governing factor in the tunnel responses, a formula for the explosion blast wave over-pressure at a certain distance from the detonation center point inside the tunnel was derived by using the dimensional analysis theory. By comparing the results computed by the formula with experimental results which were obtained before, the formula was proved to be very applicable at some instance. The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.
文摘Maximum charge per delay in a blasting round is universally accepted as the influencing parameter to quantify magni-tude of vibration for any distance of concern. However, for any blasting round experimental data reveals that for same charge per delay magnitude of vibration varies with total charge. Considering linear transmission of blast waves, the paper firstly investigates into the influence of explosive weight, blast design parameters and geology of strata on magnitude and characteristics of vibration parameters and thereafter communicates that possibly interference of blast waves generated from same and different holes of a blasting round result into variation in vibration magnitude. The paper lastly developed a mathematical model to evaluate points of interference of blast waves generated from single- and multi-hole blasting round.
文摘All underwater drilling and blasting operations generate seismic waves.However,due to a lack of suitable vibration sensing instruments,most studies on the propagation of seismic waves have been limited to shorelines near construction areas or wharfs,whereas comparatively few studies have beerconducted on the larger seafloor itself.To address this gap,a seafloor vibration sensor system was developed and applied in this study that consists of an autonomous acquisition storage terminal,soft-ware platform,and hole-plugging device that was designed to record the blasting vibration intensities received through submarine rocks at a given measurement point.Additionally,dimensional analyses were used to derive a predictive equation for the strength of blast vibrations that considered the in fluence of the water depth.By combining reliable vibration data obtained using the sensor system in submarine rock and the developed predictive equation,it was determined that the water depth was ar important factor influencing the measured vibration strength.The results using the newly derivedequation were compared to those determined using the Sadowski equation,which is commonly used on land,and it was found that predictions using the derived equation were closer to the experimental values with an average error of less than 10%,representing a significant improvement.Based on these results the developed sensor system and preliminary theoretical basis was deemed suitable for studying the propagation behavior of submarine seismic waves generated by underwater drilling and blasting operations.
基金funded by Key R&D Projects in Hubei Province (Grant No.2020BCA084)Innovative Group Project of Hubei Natural Science Foundation (Grant No.2020CFA043)。
文摘Prototype experiments were carried out on the explosion-proof performance of the RC blast wall.The mass of TNT detonated in the experiments is 5 kg and 20 kg respectively.The shock wave overpressure was tested in different regions.The above experiments were numerically simulated,and the simulated shock wave overpressure waveforms were compared with that tested and given by CONWEP program.The results show that the numerically simulated waveform is slightly different from the test waveform,but similar to CONWEP waveform.Through dimensional analysis and numerical simulation under different working conditions,the equation for the attenuation rate of the diffraction overpressure behind the blast wall was obtained.According to the corresponding standards,the degree of casualties and the damage degree of the brick concrete building at a certain distance behind the wall can be determined when parameters are set.The above results can provide a reference for the design and construction of the reinforced concrete blast wall.
