Experimental Study On Millisecond Blasting Base On Slope Elevation Amplification Effect

Now most of mine for control of blasting seismic effect use millisecond blasting method,however,due to the influence of the elevation amplification effect,the propagation law of blasting seismic wave in rock slope in the spread and at the level of rock mass differs from each other,the millisecond time choice makes it difficult to choose micro-interval time.Therefore,it furnished with important theoretical guiding significance for the stability control of the slope and the safe and efficient mining of the mine to study the vibration effect and propagation rule of blasting seismic wave on the slope step when the millisecond blasting is applied,and rationally select the best millisecond time.This paper starts with the propagation law of blasting seismic waves under the influence of elevation difference,base on Science and Technology Research Project of Jiangxi Provincial Education Department(Grant No.GJJ 160643)and builds a step model of concrete slope based on the theory of blasting simulation.Using digital electronic detonator conducted blasting test in blasting simulation of slope model of Oms-21ms in total of 10 groups with different millisecond delayed,obtained the blasting vibration signal data in homogenizing conditions and weak structural plane conditions,and established the numerical model corresponding to the test results validly using LS-DYNA software,the following are conclusions:(1)by analyzing the different interval peak particle vibration velocity,compared with the simultaneous blasting,interval blasting can effectively reduce blasting vibration intensity;different millisecond intervals decreased vibration effect dissimilarly,with T as the seismic wave cycle,the time interval for T/2,3T/2,5T/2...play a good effect on the waveform superposition interference and vibration reduction in the middle and far zone of the blasting.(2)in contrast to amplification coefficient,the elevation amplification effect is greatly influenced by the amount of single dose and the elevation amplification effect of simultaneous blasting is more obvious than millisecond blasting while in the case of the same total dose;blasting seismic wave attenuation will be produced after through the weak structural plane,it is concluded the performance of the reduced particle vibration velocity and the weakened elevation amplification effect.When the millisecond blasting is applied,the elevation amplification effect produced by different interval time is quite different,and there is no obvious correlation in the amplification coefficient of each millisecond time and the maximum particle velocity.(3)the dynamic response characteristics show that through the weak structural plane will make it real that the frequency of the blasting seismic wave is closer to the natural frequency of the structural body,which is more likely to generate resonance and amplify the signal energy when the blasting seismic wave propagates on the high slope.In the condition of this model,the dynamic response to the blasting seismic wave in the 4 step is the most obvious,and it is more likely to cause the resonance phenomenon.(4)optimal analysis and the time interval is conducted in the millisecond blasting test based on the comprehensive evaluation index of maximum particle vibration velocity,elevation amplification coefficient,blasting duration,marginal total energy,the dynamic response of the structure,provides a new way of time the selection with the future selection of reasonable millisecond interval time for the site slope.