An analytical relation between burden velocity and ratio of burden to blasthole diameter is developed in this paper.This relation is found to be consistent with the measured burden velocities of all 37 full-scale blas...An analytical relation between burden velocity and ratio of burden to blasthole diameter is developed in this paper.This relation is found to be consistent with the measured burden velocities of all 37 full-scale blasts found from published articles.These blasts include single-hole blasts,multi-hole blasts,and simultaneously-initiated blasts with various borehole diameters such as 64 mm,76 mm,92 mm,115 mm,142 mm and 310 mm.All boreholes were fully charged.The agreement between measured and calculated burden velocities demonstrates that this relation can be used to predict the burden velocity of a wide range of full-scale blast with fully-coupled explosive charge and help to determine a correct delay time between adjacent holes or rows in various full-scale blasts involved in tunnelling(or drifting),surface and underground mining production blasts and underground opening slot blasts.In addition,this theoretical relation is found to agree with the measured burden velocities of 9 laboratory small-scale blasts to a certain extent.To predict the burden velocity of a small-scale blast,a further study or modification to the relation is necessary by using more small-scale blasts in the future.展开更多
Investigating rock fragmentation mechanisms under blasting and developing new blasting technologies are important and challenging directions for blast engineering.Recently,with the development of experimental techniqu...Investigating rock fragmentation mechanisms under blasting and developing new blasting technologies are important and challenging directions for blast engineering.Recently,with the development of experimental techniques,the fundamental theory of rock blasting has been extensively studied in the past few decades and has made important achievements in the full understanding of the rock fracturing process under blast loading.It is thus imperative to systematically review the progress in this direction.This paper mainly focuses on the experimental study of rock blasting,including the distribution characteristic of blast energy,evolution of the blast stress field,propagation mechanism of cracks,interaction mechanism between blast waves and cracks,and influence of geostatic stress on rock fragmentation.In addition,some newly developed blasting technologies and their applications are briefly presented.This review could provide comprehensive insights to guide the study on the rock fracturing mechanism under blasting and further provide meaningful guidance for optimizing blast parameters in engineering.展开更多
Fracture and ground vibration of rock subjected to different decoupling decked charges are investigated based on the numerical simulation.The dynamic pressure value is studied,which demonstrates that simulation of fra...Fracture and ground vibration of rock subjected to different decoupling decked charges are investigated based on the numerical simulation.The dynamic pressure value is studied,which demonstrates that simulation of fracture zone is feasible.Attenuation index of dynamic pressure is 2.06,2.05 and 1.93 for air,water and sand intervals respectively.The small attenuation of sand interval results in the large ground vibration.The predicted vertical vibration waveform and peak particle velocities(PPV) in far-field are in agreement with the monitoring results.The results show that the air and water decked charges can improve the effect of rock fracture in near-field and reduce ground vibration in far-field.展开更多
Ground vibration, as the most critical public hazard of blasting, has received much attention from the community. Many countries established national standards to suppress vibration impact on structures, but a world-a...Ground vibration, as the most critical public hazard of blasting, has received much attention from the community. Many countries established national standards to suppress vibration impact on structures, but a world-accepted blasting vibration criterion on human safety is still missing. In order to evaluate human response to the vibration from blasting excavation of a large-scale rock slope in China, this study aims to suggest a revised criterion. The vibration frequency was introduced to improve the existing single-factor(peak particle velocity) standard recommended by the United States Bureau of Mines(USBM). The feasibility of the new criterion was checked based on field vibration monitoring and investigation of human reactions. Moreover, the air overpressure or blast effects on human beings have also been discussed. The result indicates that the entire zone of influence can be divided into three subzones: severe-annoyance, light-annoyance and perception zone according to the revised safety standard. Both the construction company and local residents have provided positive comments on this influence degree assessment, which indicates that the presented criterion is suitable for evaluating human response to nearby blasts. Nevertheless, this specific criterion needs more field tests and verifications before it can展开更多
A new blasting approach of combined blastholes with different diameters is proposed to solve the problems of oversize boulders and rock toes in open-pit mine. A non-ideal detonation model and a statistical damage cons...A new blasting approach of combined blastholes with different diameters is proposed to solve the problems of oversize boulders and rock toes in open-pit mine. A non-ideal detonation model and a statistical damage constitutive model are implemented in dynamic finite element analysis to investigate the formation mechanism of oversize boulders and toes. The damage distribution and evolution process of rock blasting fragmentation is simulated, and the scheme is further optimized. Numerical analysis results showed that pocket charges and satellite blastholes can only improve bench top fragmentation, but they cannot reduce the oversize in the middle and bottom of bench as well as the toe problem. The new blasting approach of combined blastholes with different diameters can effectively reduce the oversize boulders and toes as well as the production costs.展开更多
The explosion effects and physical process in rock mass by cylindrical charges are discussed.The maximum explosion cavity radius and the coefficient of effective explosion work are found through mechanical model and n...The explosion effects and physical process in rock mass by cylindrical charges are discussed.The maximum explosion cavity radius and the coefficient of effective explosion work are found through mechanical model and numerical method.The dependance of explosion parameters on time is got.The results show that the maximum explosion cavity radius produced by cylindrical charge of ammonium trinitro-toluene No.2 explosive in limestone and diabase is 1.50 and 1.26 times respectively as much as that of blasthole;and the coefficient of effective explosion work is 0.71 and 0.54 respectively as much as that of the blasthole.展开更多
Given their technical and economic advantages,the application of explosive substances to rock mass excavation is widely used.However,because of serious environmental restraints,there has been an increasing need to use...Given their technical and economic advantages,the application of explosive substances to rock mass excavation is widely used.However,because of serious environmental restraints,there has been an increasing need to use complex tools to control environmental effects due to blast-induced ground vibrations.In the present study,an artificial neural network(ANN)with k-fold cross-validation was applied to a dataset containing 1114 observations that was obtained from published results;furthermore,quantitative and qualitative parameters were considered for ground vibration amplitude prediction.The best ANN model obtained has a maximum coefficient of determination of 0.840 and a mean absolute error of 5.59 and it comprises 17 input parameters,12 neurons in a one-layer hidden layer,and a sigmoid transfer function.Compared with the traditional models,the model obtained using the proposed methodology demonstrated better generalization ability.Furthermore,the proposed methodology offers an ANN model with higher prediction ability.展开更多
文摘An analytical relation between burden velocity and ratio of burden to blasthole diameter is developed in this paper.This relation is found to be consistent with the measured burden velocities of all 37 full-scale blasts found from published articles.These blasts include single-hole blasts,multi-hole blasts,and simultaneously-initiated blasts with various borehole diameters such as 64 mm,76 mm,92 mm,115 mm,142 mm and 310 mm.All boreholes were fully charged.The agreement between measured and calculated burden velocities demonstrates that this relation can be used to predict the burden velocity of a wide range of full-scale blast with fully-coupled explosive charge and help to determine a correct delay time between adjacent holes or rows in various full-scale blasts involved in tunnelling(or drifting),surface and underground mining production blasts and underground opening slot blasts.In addition,this theoretical relation is found to agree with the measured burden velocities of 9 laboratory small-scale blasts to a certain extent.To predict the burden velocity of a small-scale blast,a further study or modification to the relation is necessary by using more small-scale blasts in the future.
文摘Investigating rock fragmentation mechanisms under blasting and developing new blasting technologies are important and challenging directions for blast engineering.Recently,with the development of experimental techniques,the fundamental theory of rock blasting has been extensively studied in the past few decades and has made important achievements in the full understanding of the rock fracturing process under blast loading.It is thus imperative to systematically review the progress in this direction.This paper mainly focuses on the experimental study of rock blasting,including the distribution characteristic of blast energy,evolution of the blast stress field,propagation mechanism of cracks,interaction mechanism between blast waves and cracks,and influence of geostatic stress on rock fragmentation.In addition,some newly developed blasting technologies and their applications are briefly presented.This review could provide comprehensive insights to guide the study on the rock fracturing mechanism under blasting and further provide meaningful guidance for optimizing blast parameters in engineering.
文摘Fracture and ground vibration of rock subjected to different decoupling decked charges are investigated based on the numerical simulation.The dynamic pressure value is studied,which demonstrates that simulation of fracture zone is feasible.Attenuation index of dynamic pressure is 2.06,2.05 and 1.93 for air,water and sand intervals respectively.The small attenuation of sand interval results in the large ground vibration.The predicted vertical vibration waveform and peak particle velocities(PPV) in far-field are in agreement with the monitoring results.The results show that the air and water decked charges can improve the effect of rock fracture in near-field and reduce ground vibration in far-field.
基金the Chinese National Programs for Fundamental Research and Development(973 Program)under Grant No.2011CB013501the Chinese National Science Fund for Distinguished Young Scholars under Grant No.51125037the Chinese National Natural Science Foundation under Grant Nos.51179138,51279135,51279146 and 51009013
文摘Ground vibration, as the most critical public hazard of blasting, has received much attention from the community. Many countries established national standards to suppress vibration impact on structures, but a world-accepted blasting vibration criterion on human safety is still missing. In order to evaluate human response to the vibration from blasting excavation of a large-scale rock slope in China, this study aims to suggest a revised criterion. The vibration frequency was introduced to improve the existing single-factor(peak particle velocity) standard recommended by the United States Bureau of Mines(USBM). The feasibility of the new criterion was checked based on field vibration monitoring and investigation of human reactions. Moreover, the air overpressure or blast effects on human beings have also been discussed. The result indicates that the entire zone of influence can be divided into three subzones: severe-annoyance, light-annoyance and perception zone according to the revised safety standard. Both the construction company and local residents have provided positive comments on this influence degree assessment, which indicates that the presented criterion is suitable for evaluating human response to nearby blasts. Nevertheless, this specific criterion needs more field tests and verifications before it can
基金supported by Chinese National Natural Science Foundation (No. 51809016 and No. 51979152)Chongqing Municipal Natural Science Foundation (No. cstc2019jcyjmsxmX0645)
文摘A new blasting approach of combined blastholes with different diameters is proposed to solve the problems of oversize boulders and rock toes in open-pit mine. A non-ideal detonation model and a statistical damage constitutive model are implemented in dynamic finite element analysis to investigate the formation mechanism of oversize boulders and toes. The damage distribution and evolution process of rock blasting fragmentation is simulated, and the scheme is further optimized. Numerical analysis results showed that pocket charges and satellite blastholes can only improve bench top fragmentation, but they cannot reduce the oversize in the middle and bottom of bench as well as the toe problem. The new blasting approach of combined blastholes with different diameters can effectively reduce the oversize boulders and toes as well as the production costs.
文摘The explosion effects and physical process in rock mass by cylindrical charges are discussed.The maximum explosion cavity radius and the coefficient of effective explosion work are found through mechanical model and numerical method.The dependance of explosion parameters on time is got.The results show that the maximum explosion cavity radius produced by cylindrical charge of ammonium trinitro-toluene No.2 explosive in limestone and diabase is 1.50 and 1.26 times respectively as much as that of blasthole;and the coefficient of effective explosion work is 0.71 and 0.54 respectively as much as that of the blasthole.
基金the support of CERENA–Center for Natural Resources and Environment(strategic project FCT-UID/ECI/04028/2019),Portugal.
文摘Given their technical and economic advantages,the application of explosive substances to rock mass excavation is widely used.However,because of serious environmental restraints,there has been an increasing need to use complex tools to control environmental effects due to blast-induced ground vibrations.In the present study,an artificial neural network(ANN)with k-fold cross-validation was applied to a dataset containing 1114 observations that was obtained from published results;furthermore,quantitative and qualitative parameters were considered for ground vibration amplitude prediction.The best ANN model obtained has a maximum coefficient of determination of 0.840 and a mean absolute error of 5.59 and it comprises 17 input parameters,12 neurons in a one-layer hidden layer,and a sigmoid transfer function.Compared with the traditional models,the model obtained using the proposed methodology demonstrated better generalization ability.Furthermore,the proposed methodology offers an ANN model with higher prediction ability.
