The distribution characteristics of collapse ratios of buildings in Kobe city due to the 1995 M7.2 Hyogo-ken Nanbu, Japan (Kobe) earthquake and the interferenres due to SH or P-SV and the second surface waves propagat...The distribution characteristics of collapse ratios of buildings in Kobe city due to the 1995 M7.2 Hyogo-ken Nanbu, Japan (Kobe) earthquake and the interferenres due to SH or P-SV and the second surface waves propagating in heterogeneous medium are discussed in this paper by using numerical simulation technique of wave equation. The staggered grid real value fast Fourier transform differentiation (SGRFFTD) is used in the pseudospectral method of ground motion simulations because of its speed, high stability and accuracy. The results show that the maximum amplitude of simulated acceleration waveforms on the ground coincides well with the complicated distributions of collapse ratios of buildings. The peak collapse ratio of buildings away from the earthquake fault also coincides well with the peak ground acceleration. The spatial interference process is analyzed by using the snap shots of seismic wave propagation. The peak ground acceleration is probably caused by the interferences due to the second surfare wave transmitting from the bedrock to sedimentary basin and the upward body wave. Analyses of the interference process show that seismic velocity structure and geologic structure strongly influence the distribution of the maximum amplitude of acceleration waveforms. Interferences occurring near the basin boundary are probably the cause of the peak collapse ratio of buildings away from the fault. Therefore it is necessary to analyze wave propagations and interference process using numerical simulation strategy for studies on the seismic disasters.展开更多
Influences on the ground motion simulations by soil amplification effects and multiple seismic wave interfer- ences in the heterogeneous medium are investigated. Detailed velocity structure obtained from the microtrem...Influences on the ground motion simulations by soil amplification effects and multiple seismic wave interfer- ences in the heterogeneous medium are investigated. Detailed velocity structure obtained from the microtremor array sur- vey is adopted in the ground motion simulation. Analyses for amplification ratios of core samples of ten drill holes with 40 m deep in the sedimentary layers show that the soil amplifi- cation ratio influences nonlinearly the seismic ground motion. Based on the above analysis results, the ground motion in the heavily damaged zone in the Japanese Kobe earthquake of 1995 is simulated in a digital SH seismic wave model by using the pseudospectral method with the staggered grid RFFT differentiation (SGRFFTD). The simulated results suggest that the heterogeneous velocity structure results in a compli- cated distribution of the maximum amplitudes of accelera- tion waveforms with multiple peaks at the surface. Spatial distribution of the maximum amplitudes coincides well with that of collapse ratios of buildings in Kobe. The dual peaks of the collapse ratios away from the earthquake fault coincide well with the double peak amplitudes of simulated seismic acceleration waves also. The cause for the first peak ampli- tude of the ground motion is attributable to the interference of the secondary surface wave from the bedrock propagating horizontally along the surface sedimentary layer and the body wave from the basin bottom according to analyses of wave snapshots propagating in inhomogeneous structure of the Osaka group layers. The second peak amplitude of the ground motion may be attributive to the interference of the secondary surface wave from the tunneling waves in the shallow sediments and the body wave. It is important for the study on complicated distributions of earthquake damages to investigate influences on the ground motion by soil amplifi- cation effects and multiple seismic wave interferences due to the structure. Explorations of the structure to the bedrock are necessary for the urban mitigation disaster. Seismic wave simulations are valid for aseismatic study.展开更多
On the evening of July 13, after Samaranch, President of the International Olympic Committee (IOC), announced in the International Trade Centre in Moscow that Beijing would host the Summer Olympic Games in 2008, a mov...On the evening of July 13, after Samaranch, President of the International Olympic Committee (IOC), announced in the International Trade Centre in Moscow that Beijing would host the Summer Olympic Games in 2008, a moving scene was being projected, on the large screen in the press center on the first floor: He Zhenliang, with tears in his eyes, was embracing his fellow IOC members who were coming up to shake hands with him in celebration.展开更多
文摘The distribution characteristics of collapse ratios of buildings in Kobe city due to the 1995 M7.2 Hyogo-ken Nanbu, Japan (Kobe) earthquake and the interferenres due to SH or P-SV and the second surface waves propagating in heterogeneous medium are discussed in this paper by using numerical simulation technique of wave equation. The staggered grid real value fast Fourier transform differentiation (SGRFFTD) is used in the pseudospectral method of ground motion simulations because of its speed, high stability and accuracy. The results show that the maximum amplitude of simulated acceleration waveforms on the ground coincides well with the complicated distributions of collapse ratios of buildings. The peak collapse ratio of buildings away from the earthquake fault also coincides well with the peak ground acceleration. The spatial interference process is analyzed by using the snap shots of seismic wave propagation. The peak ground acceleration is probably caused by the interferences due to the second surfare wave transmitting from the bedrock to sedimentary basin and the upward body wave. Analyses of the interference process show that seismic velocity structure and geologic structure strongly influence the distribution of the maximum amplitude of acceleration waveforms. Interferences occurring near the basin boundary are probably the cause of the peak collapse ratio of buildings away from the fault. Therefore it is necessary to analyze wave propagations and interference process using numerical simulation strategy for studies on the seismic disasters.
文摘Influences on the ground motion simulations by soil amplification effects and multiple seismic wave interfer- ences in the heterogeneous medium are investigated. Detailed velocity structure obtained from the microtremor array sur- vey is adopted in the ground motion simulation. Analyses for amplification ratios of core samples of ten drill holes with 40 m deep in the sedimentary layers show that the soil amplifi- cation ratio influences nonlinearly the seismic ground motion. Based on the above analysis results, the ground motion in the heavily damaged zone in the Japanese Kobe earthquake of 1995 is simulated in a digital SH seismic wave model by using the pseudospectral method with the staggered grid RFFT differentiation (SGRFFTD). The simulated results suggest that the heterogeneous velocity structure results in a compli- cated distribution of the maximum amplitudes of accelera- tion waveforms with multiple peaks at the surface. Spatial distribution of the maximum amplitudes coincides well with that of collapse ratios of buildings in Kobe. The dual peaks of the collapse ratios away from the earthquake fault coincide well with the double peak amplitudes of simulated seismic acceleration waves also. The cause for the first peak ampli- tude of the ground motion is attributable to the interference of the secondary surface wave from the bedrock propagating horizontally along the surface sedimentary layer and the body wave from the basin bottom according to analyses of wave snapshots propagating in inhomogeneous structure of the Osaka group layers. The second peak amplitude of the ground motion may be attributive to the interference of the secondary surface wave from the tunneling waves in the shallow sediments and the body wave. It is important for the study on complicated distributions of earthquake damages to investigate influences on the ground motion by soil amplifi- cation effects and multiple seismic wave interferences due to the structure. Explorations of the structure to the bedrock are necessary for the urban mitigation disaster. Seismic wave simulations are valid for aseismatic study.
文摘On the evening of July 13, after Samaranch, President of the International Olympic Committee (IOC), announced in the International Trade Centre in Moscow that Beijing would host the Summer Olympic Games in 2008, a moving scene was being projected, on the large screen in the press center on the first floor: He Zhenliang, with tears in his eyes, was embracing his fellow IOC members who were coming up to shake hands with him in celebration.
