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371.
Current state of integrated earthquake simulation for earthquake hazard and disaster 总被引:1,自引:0,他引:1
This paper presents the current state of integrated simulation for earthquake hazard and disaster. This simulation takes advantage
of the macro–micro analysis method; this method estimates an earthquake’s strong motion with high spatial and temporal resolution,
using the bounding medium theory to obtain optimistic and pessimistic estimates of expected strong motion distribution and
the singular perturbation expansion that results in an efficient multi-scale analysis. Integrated earthquake simulation calculates
seismic responses for all structures in a target area, inputting simulated strong ground motion to a structure analysis method
that is plugged into the system by means of a wrapper; a suitable method, linear or nonlinear, is chosen depending on the
type of the structure. The results of all simulations are visualized so that residences and government officials can share
a common recognition of earthquake hazard and disaster. Two examples of this integrated earthquake simulations are presented;
one is made by plugging nonlinear structure analysis methods into the system, and the other is made for an actual city, the
computer model of which is constructed with the help of available geographical information systems. 相似文献
372.
Geochemical Process of Gas Hydrate Formation in the Nankai Trough Based on Chloride and Isotopic Anomalies in Interstitial Water 总被引:2,自引:0,他引:2
Abstract: Interstitial water expelled from gas hydrate-bearing and -free sediments in the Nankai Trough are analyzed in terms of Cl-, SO4 2 -, δ18 O and δD. The baselines for the Cl- concentration and δ18 O value are close to seawater values (530 mM and 0%), indicating that the interstitial water is of seawater origin. The δD values decrease with depth, implying isotopic exchange of hydrogen between upwelling biogenic methane depleted in D and interstitial water. The Cl- concentrations in gas hydrate-bearing sediments are anomalously low, while the δ18 O and δD values are both high, suggesting that the water forming these gas hydrates was poor in Cl- and enriched in 18 O and D during gas hydrate formation. Calculation of the gas hydrate saturations using Cl "and δ18 O anomalies gives results of up to 80 % in sand, and shows that the δ18 O baseline is not consistent with the Cl" baseline. The δ18 O baseline increases by +1% in gas hydrate-free clay and silt. This is considered to be caused by clustering of water molecules after gas hydrate dissociation in response to the upward migration of the base of gas hydrate stability, as indicated by the presence of a double bottom-simulating reflector at this site. The water clusters enriched in 18 O are responsible for the increase in the δ18 O baseline with normal Cl". The abrupt shallowing of the base of gas hydrate stability may induce the dissociation of gas hydrates and the accumulation of gases in the new stability zone, representing a geological process that increases gas hydrate saturation. 相似文献
373.
The drag and added mass coefficients of a truss leg of an ocean platform are obtained by using the forced-oscillation technique in a still water. Higher order forces and lift forces are also measured.The drag and inertia coefficients of the truss leg model are obtained by measuring the wave forces acting on it in regular deep waves. The moment lever of the wave force is compared with theoretical results. 相似文献
374.