The Generation And Attenuation Mechanism Of Blasting Induced Seismic Wave

As an important means of technology blasting plays an increasingly important role in the production and construction. But due to the blasting process involves mechanics, gas dynamics, rock mechanics and stress wave theory and many other disciplines, the quantitative study of the blasting process and the effect is still not perfect. Blasting vibration as blasting pollution first, because of its universality and the destructive effects of the rock remain and nearby building (structure) or facilities, the generation and attenuation mechanism of seismic wave has been important research topic in the field of rock blasting.Through theoretical analysis and numerical simulation, this document studied the generation mechanism of blasting seismic wave, especially the shear wave, analysed the vibration amplitude, energy and frequency attenuation law and influencing factors of the seismic wave, established a spherical kits excitation spectrum of the seismic waves expression and blasting vibration centroid frequency attenuation formula.First by studying type and production process of seismic wave, analysed the wave equation and mechanism of the P, S and R-wave, and focused on the S-wave generation mechanism. Rock blasting rock fragmentation gun crushing and cracking of the rock mass around the hole, the interaction of rock mass stress wave and rock interface, the short columnar kits instantaneous detonation, the explosion source deviation from the spherical cavity centers and non-spherically symmetric cavity will stimulate the S-wave. The unevenness of the medium, the presence of the rock interface, the load and the structure of the asymmetry of the impact of the detonation process so may lead to the S-wave generation whose amplitude may exceed the P wave.It studied the velocity's attenuation mechanism and law of the blasting seismic wave vibration. Seismic wave attenuation mechanisms include geometrical spreading, the medium damping effect and interaction with rock media interface. The blasting vibration velocity attenuation law, blasting vibration attenuation coefficient with frequency and geological relations of the quality factor, indicating that the higher the frequency, the faster the blasting vibration attenuation; the greater the Geological quality factor, the better the lithology, blasting vibration attenuation is smaller.Have studied the the blasting seismic energy attenuation law. Blasting seismic wave energy can reflect the bursting of the amplitude, frequency and duration of the impact of the three elements. By theoretical analysis, the energy in the process of blasting seismic wave propagation attenuation relationship, indicating that the attenuation coefficient of the peak energy with distance twice the attenuation coefficient of the blasting vibration velocity; easier to attenuation of high-frequency seismic waves, seismic wave vibration frequency to low frequency partial shift trend, and in the far zone of the explosion source, the surface waves carry the main blasting vibration energy.It studied the seismic wave's frequency attenuation mechanisms and attenuation law. Focus on the seismic waves which spherical kits excited in the viscoelastic medium, to derive the expression of the spectrum, and analyzes the influencing factors of the blasting vibration spectrum characteristics. Blasting vibration spectrum characteristics depend on the critical source parameters and rock mass medium parameters, including the size of the blast load, elastic cavity radius (or rock blasting the rupture zone boundary), load rise time, load duration, P-wave velocity of the rock and the quality factor and other parameters.Due to the multi-peak structure of blasting seismic amplitude-frequency distribution curve and the factor of the high-frequency seismic wave attenuation fast, blasting vibration frequency does not follow strict attenuation with increasing of the distance away the blasting center, and local mutations in the dissemination process or jumping phenomenon, resulting the frequency attenuation empirical formula fitting process discreteness. Thus, in blasting seismic wave frequency attenuation law research, the introduction of the blasting vibration centroid frequency instead of the traditional main vibration frequency shows obvious attenuation law in the process of blasting seismic wave propagation, which has the linear relationship with ratio of the rock mass longitudinal wave speed and explosive cavity radius, and has the power law relationship with the ratio of the critical cavity radius and the distance from the explosion center. On this basis, the thesis established semi-empirical semi-theoretical formula of the blasting vibration centroid frequency attenuation.