Propagation Law Of Blasting Seismic Waves At Different Obliquity Of The Interface In Open Pit Slope

In this paper,blasting seismic wave propagation at the interface was taken as the research object.The propagation law and attenuation characteristics of blasting seismic waves at different obliquity on open-pit slope were discussed through field monitoring of blasting vibration and physical model simulation blasting test,and it was studied that the characteristics of blasting vibration response of the slope by the method of response spectrum analysis.The work was supported by a Scientific Research Project of Jiangxi Provincial Education Department(GJJ160643),and the Project of the Key Disciplines of Jiangxi University of Science and Technology(3304000004).The main contents and conclusions are as follows:(1)The blasting vibration signal energy of open slopes mainly distributes in 0~64Hz,the blasting vibration signal energy mainly distribution band become gradually narrower with the increasing of altitude,and the main vibration frequency tends to low frequency band;The more developed rock joints and fissures,the larger the relative energy distribution band gradually widens,and the main vibration and has a trend towards higher frequency bands,it is due to the fact that the multi-percussive type of rock structure developed in the actual formation fractures responds to blasting seismic waves.The blasting vibration velocity and energy of the blasting seismic wave have a certain elevation amplification effect,and there is a difference in the vibration amplification coefficient in the frequency bands at a given slope.(2)The peak vibration velocity of the same distance has a greater attenuation than the homogeneous region when the blasting seismic wave passed though the interface under the condition that the crack is not filled or is filled with sand,and the attenuation which the fracture is not filled with the medium is greater than that of the crack filling medium,so the vibration isolation effect is also more obvious.The percentage of attenuation in the vertical direction of the first measurement point decrease with the increasing of the interface obliquity when the blasting seismic wave passed through the interface,and the attenuation percentage show certain negative correlation respectively,but it is adverse in the radial direction.The percentage of vertical or radial attenuation of vibration may increase with the increase of the angle which formed between vibration direction and the interface after the blasting seismic wave passed through the first measurement point.(3)The energy of the first measured point of the simulated blasting seismic wave is mainly concentration below 500 Hz when it passed through the interface.It is between 50 Hz and 250 Hz that the main vibration frequency band under different conditions.The main vibration band has a tendency to develop toward the lower frequency band when the simulated blasting seismic wave passed through the interface compare with the homogeneous conditions,and the trend is more obvious in non-filled crack than it in filled crack.The simulated blasting seismic wave produce more diffraction at the non-filled part of the fracture,the peak ratios of the P and SV waves are between 1.029 and 1.335 with little change at the first measurement point.The simulated blasting seismic wave also produces the transformation of wave type at the interface with filled by sand,the peak ration of P and SV waves are between 0.715 and 1.301 at the first measurement point.From a general point of view,the peak ratio of P and SV waves increases with the increase of the interface obliquity.(4)The frequency corresponding to the main peak of the response spectrum of the simulated blasting seismic wave is reduced in the order of homogeneous conditions,crack filled with sand,and crack non-filled.The response of the slope to the blasting seismic wave presents a multi-mode and multi-modality,the dynamic magnification times of blasting vibration velocity response depends on the structure of slope itself.Different structures have different amplification effects on blasting seismic waves,and the same structure has different amplification effects on different vibration direction of blasting seismic waves.