The accurate identification of delay time in millisecond blasting plays an important role in the optimization of blasting design and reduction of vibration effect. Through a case study of a surge shaft blasting projec...The accurate identification of delay time in millisecond blasting plays an important role in the optimization of blasting design and reduction of vibration effect. Through a case study of a surge shaft blasting project, the capability of the EMD （empirical mode decomposition） method in identifying the delay time of short millisecond blasting with precise initiation was compared with the instantaneous energy method based on Hilbert-Huang transform （HHT）. The recognition rate of the EMD method was more than 80%, while the instantaneous energy method was less than 25%. By analyzing the instantaneous energy of single-hole blasting signal, it was found that the instantaneous energy method was adaptable to millisecond blasting with delay time longer than half of the energy peak period. The EMD method was used to identify delay time of millisecond blasting in Zijinshan open-pit mine. According to the identification results, the blasting parameters were optimized for controlling the blast-induced vibration and reducing the large block ratio. The field data showed that the velocity peak of ground vibration was reduced by more than 30%under almost the same maximum charge per delay by the optimization of delay time and detonating detonators. Combining with slag-remaining blasting and burden optimization of the first row, the large block ratio was reduced to less than 3%. The research results proved that the identification method based on HHT was feasible to optimize the blasting design. The identification method is also of certain reference value for design optimization of other similar blasting projects.展开更多
Drilling and blasting play vital roles in opencast mining. These operations not only affect the cost of production directly but as well and significantly, the overall operational costs. This research was carried out t...Drilling and blasting play vital roles in opencast mining. These operations not only affect the cost of production directly but as well and significantly, the overall operational costs. This research was carried out to find a possible way of optimizing the drilling and blasting operations in an open pit mine of Somair (Société des Mines de l’Air), in the Niger Republic. In order to optimize the drilling operation, the time taken by two drilling machines to accomplish the same task was analyzed statistically. The result indicates that the Down the Hole Hammer Drilling Rig (DMNo406) is more efficient than the Drill Master (DM405). The relative unit consumption of two explosives (Explus and Nitram 9), when used under the same operating conditions, were also considered and the results indicate Explus to be more economical per unit consumption with a range of 0.15 g/t–0.183 g/t, when compared with Nitram 9 with a unit consumption range of 0.19 g/t-0.24 g/t in the study area.展开更多
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
Mining blasts may be defined as the use of explosive charges in a controlled manner by following a tightly controlled timing sequence according to an assigned firing order. Changes of timing between charges may result...Mining blasts may be defined as the use of explosive charges in a controlled manner by following a tightly controlled timing sequence according to an assigned firing order. Changes of timing between charges may result in an altered firing order and failure of the blasting sequence, which can cause high vibration levels, poor fragmentation, and/or an undesirable rock mass movement direction. Despite the importance of timing in determining mine blast results, there exists a lack of methodologies or tools with which to assess performance of a complete blast based on delay type and timing sequence. This document applies reliability engineering principles to evaluate the performance of a mine blast. The analyses are based on test results of the accuracy and precision of electronic and pyrotechnic detonators for typical firing times used in a surface coal mine, but may be applied to a variety of mines and timing scenarios.展开更多
Since the Mesozoic, southeastern North China Craton has experienced intense crustal thinning and lithosphere destruction. Some of the responses of the deep activity in the upper crust crystalline basement have been re...Since the Mesozoic, southeastern North China Craton has experienced intense crustal thinning and lithosphere destruction. Some of the responses of the deep activity in the upper crust crystalline basement have been retained in a series of tectonic evolution. The study of the upper crust velocity structure,especially the properties of the basement interface, is of great significance for studying the tectonic evolution and seismic hazard in the southeastern part of North China. In this study, we selected Pg waves of the blasting seismic data in the southeastern part of North China in recent years, which reflect the west Shandong uplift, offshore sedimentary basins and the Tanlu Fault zone and the Sulu orogenic transition zone, to study the structural and seismological characteristics of basement in North China Craton. The results of this study showed as follows: First, the obvious lag of Pg wave arrival time in Dongying depression and North Jiangsu basin reveals the thick sedimentary, low velocity and unstable basement structure. Second, the advance Pg wave arrival time with high apparent velocity, which reflects the basement structure of the west Shandong uplift, indicates the thin sediments and the shallow basement. Third, combined with many geophysical phenomena, such as electrical structure, density structure and terrestrial heat flow, we hold that the Tanlu tectonic belt and the Sulu orogenic belt have experienced great lithosphere destruction and there is shallow crust and the thinnest lithosphere in the vicinity of the Tanlu fault zone.展开更多
针对实际中信道估计存在误差,从阵列信号处理的角度提出了V-BLAST(Vertical Bell Labs Layered Space-Time)OFDM系统中一种稳健的检测算法.将接收数据的协方差矩阵进行特征值分解,得到信号子空间,将存在估计误差的信道矢量向该子空间投...针对实际中信道估计存在误差,从阵列信号处理的角度提出了V-BLAST(Vertical Bell Labs Layered Space-Time)OFDM系统中一种稳健的检测算法.将接收数据的协方差矩阵进行特征值分解,得到信号子空间,将存在估计误差的信道矢量向该子空间投影,就可以得到较为准确的信道矢量,然后利用波束形成计算出检测滤波器的系数.仿真结果表明,当信道估计存在误差时,该方法性能显著优于ZF(Zero-Forcing)和MMSE(Minimum Mean Square Error)算法.展开更多
基金Project(2013BAB02B05)supported by the National 12th Five-Year Science and Technology Supporting Plan of ChinaProject(2015CX005)supported by the Innovation Driven Plan of Central South University of ChinaProject(2016zzts094)supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘The accurate identification of delay time in millisecond blasting plays an important role in the optimization of blasting design and reduction of vibration effect. Through a case study of a surge shaft blasting project, the capability of the EMD （empirical mode decomposition） method in identifying the delay time of short millisecond blasting with precise initiation was compared with the instantaneous energy method based on Hilbert-Huang transform （HHT）. The recognition rate of the EMD method was more than 80%, while the instantaneous energy method was less than 25%. By analyzing the instantaneous energy of single-hole blasting signal, it was found that the instantaneous energy method was adaptable to millisecond blasting with delay time longer than half of the energy peak period. The EMD method was used to identify delay time of millisecond blasting in Zijinshan open-pit mine. According to the identification results, the blasting parameters were optimized for controlling the blast-induced vibration and reducing the large block ratio. The field data showed that the velocity peak of ground vibration was reduced by more than 30%under almost the same maximum charge per delay by the optimization of delay time and detonating detonators. Combining with slag-remaining blasting and burden optimization of the first row, the large block ratio was reduced to less than 3%. The research results proved that the identification method based on HHT was feasible to optimize the blasting design. The identification method is also of certain reference value for design optimization of other similar blasting projects.
文摘Drilling and blasting play vital roles in opencast mining. These operations not only affect the cost of production directly but as well and significantly, the overall operational costs. This research was carried out to find a possible way of optimizing the drilling and blasting operations in an open pit mine of Somair (Société des Mines de l’Air), in the Niger Republic. In order to optimize the drilling operation, the time taken by two drilling machines to accomplish the same task was analyzed statistically. The result indicates that the Down the Hole Hammer Drilling Rig (DMNo406) is more efficient than the Drill Master (DM405). The relative unit consumption of two explosives (Explus and Nitram 9), when used under the same operating conditions, were also considered and the results indicate Explus to be more economical per unit consumption with a range of 0.15 g/t–0.183 g/t, when compared with Nitram 9 with a unit consumption range of 0.19 g/t-0.24 g/t in the study area.
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Mining blasts may be defined as the use of explosive charges in a controlled manner by following a tightly controlled timing sequence according to an assigned firing order. Changes of timing between charges may result in an altered firing order and failure of the blasting sequence, which can cause high vibration levels, poor fragmentation, and/or an undesirable rock mass movement direction. Despite the importance of timing in determining mine blast results, there exists a lack of methodologies or tools with which to assess performance of a complete blast based on delay type and timing sequence. This document applies reliability engineering principles to evaluate the performance of a mine blast. The analyses are based on test results of the accuracy and precision of electronic and pyrotechnic detonators for typical firing times used in a surface coal mine, but may be applied to a variety of mines and timing scenarios.
基金supported by the National Natural Science Foundation of China (41474077)Seismic Youth Funding of GEC (YFGEC2017001)
文摘Since the Mesozoic, southeastern North China Craton has experienced intense crustal thinning and lithosphere destruction. Some of the responses of the deep activity in the upper crust crystalline basement have been retained in a series of tectonic evolution. The study of the upper crust velocity structure,especially the properties of the basement interface, is of great significance for studying the tectonic evolution and seismic hazard in the southeastern part of North China. In this study, we selected Pg waves of the blasting seismic data in the southeastern part of North China in recent years, which reflect the west Shandong uplift, offshore sedimentary basins and the Tanlu Fault zone and the Sulu orogenic transition zone, to study the structural and seismological characteristics of basement in North China Craton. The results of this study showed as follows: First, the obvious lag of Pg wave arrival time in Dongying depression and North Jiangsu basin reveals the thick sedimentary, low velocity and unstable basement structure. Second, the advance Pg wave arrival time with high apparent velocity, which reflects the basement structure of the west Shandong uplift, indicates the thin sediments and the shallow basement. Third, combined with many geophysical phenomena, such as electrical structure, density structure and terrestrial heat flow, we hold that the Tanlu tectonic belt and the Sulu orogenic belt have experienced great lithosphere destruction and there is shallow crust and the thinnest lithosphere in the vicinity of the Tanlu fault zone.
文摘针对实际中信道估计存在误差,从阵列信号处理的角度提出了V-BLAST(Vertical Bell Labs Layered Space-Time)OFDM系统中一种稳健的检测算法.将接收数据的协方差矩阵进行特征值分解,得到信号子空间,将存在估计误差的信道矢量向该子空间投影,就可以得到较为准确的信道矢量,然后利用波束形成计算出检测滤波器的系数.仿真结果表明,当信道估计存在误差时,该方法性能显著优于ZF(Zero-Forcing)和MMSE(Minimum Mean Square Error)算法.
