Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Aus...Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Australia,by using spread velocities,amplitudes and frequency contents as the main analysis parameters.The results show that the average P-wave velocity,mean values of combined maximal amplitudes and frequencies of the first arrivals are all reduced significantly along with goaf expanding and intensity weakening of overlying strata during mining process.A full roof fracturing can make the average P-wave velocities,combined maximal amplitudes and frequencies of first arrivals reduce to about 69.8%,92.2% and 60.0%,respectively.The reduction of the above seismic parameters reveals dynamic effects of the variation of strata structure and property to the wave transmission and energy dissipation of blasting wave.The research greatly benefits further study on stability of surrounding rock under the destructive effort by mine tremor,blasting,etc,and provides experimental basis for source relocation and parameter optimization of seismic monitoring as well.展开更多
Recordings of seismic waves propagating from earthquake source to a station at the earth’s surface are a system response function. The convolution operator in time domain can be simplified as a multiplication operato...Recordings of seismic waves propagating from earthquake source to a station at the earth’s surface are a system response function. The convolution operator in time domain can be simplified as a multiplication operator in frequency domain. We discuss in frequency domain the separation of source, path and site effects for global scaling of earthquake source radiation. Also discussed are source scaling model, faulting mechanism, and the H/V inversion problems with crustal and near surface structures. Gross features of apparent source spectra appear to be not much region dependent although there may be difference between tectonic styles within a region of tectonic mixture for which we need further study as data accumulate. Vertical spectra may be a better approach to approximate source radiation, as it has less crustal amplification effects than horizontal spectra. The H/V ratio is evidently a comprehensive indicator of amplification effects from near surface to deep structure. This gives it potential as an inversion tool to deduce site crustal structure.展开更多
The inverse problem of seismology for media with attenuation is considered in this paper. Generalized Standard Linear Solid is used to describe viscoelastic media. In the numerical solution certain parameterizations c...The inverse problem of seismology for media with attenuation is considered in this paper. Generalized Standard Linear Solid is used to describe viscoelastic media. In the numerical solution certain parameterizations can be coupled, it means that true heterogeneity of the only one of parameters can be restored only as a perturbation of another. This is why important to investigate reliability of parameters recovery. By using method based on diffraction patterns it is possible to see whether the parameters are coupled. Singular value decomposition was used to study the possibility of recovering the parameters in practice. It was investigated the possibility of reconstructing of the density, impedances and attenuation properties. Coupling appears on the attenuation properties and impedances separately corresponding to the P-wave and S-wave. It is also should be noted that coupling decreases with increasing frequency range and the condition number.展开更多
基金Foundation item: Project(2010CB226805) supported by the National Basic Research Program of ChinaProject(2010QNA30) supported by the Fundamental Research Funds for the Central Universities of China+1 种基金Project supported by the Priority Academic Development Program of Jiangsu Higher Education,ChinaProjects(SZBF2011-6-B35,2012BAK04B06) supported by the National Twelfth Five-year Key Science & Technology Foundation of China
文摘Microseismic effects during the transmission of seismic waves in coal and rock mass associated with mining operation were studied by on-site blasting tests and microseismic monitoring in LW704 of Southern Colliery,Australia,by using spread velocities,amplitudes and frequency contents as the main analysis parameters.The results show that the average P-wave velocity,mean values of combined maximal amplitudes and frequencies of the first arrivals are all reduced significantly along with goaf expanding and intensity weakening of overlying strata during mining process.A full roof fracturing can make the average P-wave velocities,combined maximal amplitudes and frequencies of first arrivals reduce to about 69.8%,92.2% and 60.0%,respectively.The reduction of the above seismic parameters reveals dynamic effects of the variation of strata structure and property to the wave transmission and energy dissipation of blasting wave.The research greatly benefits further study on stability of surrounding rock under the destructive effort by mine tremor,blasting,etc,and provides experimental basis for source relocation and parameter optimization of seismic monitoring as well.
文摘Recordings of seismic waves propagating from earthquake source to a station at the earth’s surface are a system response function. The convolution operator in time domain can be simplified as a multiplication operator in frequency domain. We discuss in frequency domain the separation of source, path and site effects for global scaling of earthquake source radiation. Also discussed are source scaling model, faulting mechanism, and the H/V inversion problems with crustal and near surface structures. Gross features of apparent source spectra appear to be not much region dependent although there may be difference between tectonic styles within a region of tectonic mixture for which we need further study as data accumulate. Vertical spectra may be a better approach to approximate source radiation, as it has less crustal amplification effects than horizontal spectra. The H/V ratio is evidently a comprehensive indicator of amplification effects from near surface to deep structure. This gives it potential as an inversion tool to deduce site crustal structure.
文摘The inverse problem of seismology for media with attenuation is considered in this paper. Generalized Standard Linear Solid is used to describe viscoelastic media. In the numerical solution certain parameterizations can be coupled, it means that true heterogeneity of the only one of parameters can be restored only as a perturbation of another. This is why important to investigate reliability of parameters recovery. By using method based on diffraction patterns it is possible to see whether the parameters are coupled. Singular value decomposition was used to study the possibility of recovering the parameters in practice. It was investigated the possibility of reconstructing of the density, impedances and attenuation properties. Coupling appears on the attenuation properties and impedances separately corresponding to the P-wave and S-wave. It is also should be noted that coupling decreases with increasing frequency range and the condition number.
