Elevation Amplification Effect Of Blasting Vibration In Open Bench

With the increasing demand of mineral resources, many mines are in a period of deep mining. Surface mining production takes a large percentage of the gross number of mining, and there are about 40 percent of open pit slope which exists stability hidden trouble in different extent.Along with the growing of mining depth and height deviation, amplification effect can be found in blasting vibration. Therefore, it is of great theoretical and practical value to study the mechanism and attenuation law of height amplification effect in the propagation of blasting seismic wave and to find economical and reasonable blasting technology in mining under the guarantee of security of last slope. Introducing and combining wave theory, this paper studied the elevation amplification effect of vibration of open-bench blasting. The data gathered from Yong-ping copper mine shows that height deviation in open-bench blasting exercises a great impact on the propaganda of seismic waves, thus there are quite errors in the attenuation of sadaov’s formula applied in Yong-ping copper mine as the result of absence of consideration of height deviation. The elevation amplification effect of blasting vibration is influenced by direction: vertically, the amplification effect of amplitude is more obvious and regular and that of blasting vibration is larger compared with that of horizontal direction and radial direction.Besides, based on energy principle, the energy distribution characteristic of blasting seismic wave in different frequency band range is studied in this paper. The result demonstrates that in open-bench blasting, the energy of blasting seismic wave mainly focused on the range of 0-40 Hz and made up 96% of the gross energy averagely and with the increase of height, more energy focused on the range of 0-10 Hz, making up 51.46% of the gross energy averagely. Combining the response characteristics of the slope to harmonic components of different frequency, that proposed the mechanism of the vibration of open-bench blasting elevation amplification effect and which is based on elevation amplification effect which lead by blasting seismic wave that reflect in different dielectric layer. With the increase of open-pit slope height, slope and resonance closing to the harmonic components of natural frequency intensified elevation amplification effect further.Due to the propagation superposition of blasting seismic wave, the result obtained by Analysis Hierarchy Process(AHP) weight calculation shows that the geological conditions of open pit slope are most influential to the elevation amplification effect of blasting vibration namely magnification factors of better slope condition are bigger and the effect weight of height deviation on elevation amplification effect is the biggest if no consideration of geological conditions. Also, elevation amplification effect is relative to the blasting parameters, the ways of initiation, open-bench blasting, the blast center distance, the height deviation etc. The magnification factor increases with the rise of height until height reaches 106.67, after which the magnification factor would decrease instead. Besides, the factor increases when the maximum single-section amount of blasting cartridges went up and proportion of explosion source and distance increase until it reaches 0.06858 where the factor gains a low growth and gets stable.Using dimensional analysis, this paper formed the threshold equation of changes of blasting vibration velocity and calculated relative error by combining measured data. The relative error of proposed threshold equation is between 9.91%-13.63%, which justifies better precision over sadaov’s Vibration Formula, that of which is between 27.64%-31.96% and better description of elevation amplification effect of blasting vibration in propagation in Yong-ping copper mine open pit slope.