In order to investigate the generation and propagation of Love waves recorded in the Tokyo lowlands, we analyzed array data obtained for six events that occurred around the Kanto district. From wavenumber analysis, the following conclusions are obtained.(1) Love waves are converted from direct S-waves at the edge of a sedimentary basin. The Hachiohji tectonic line is an especially important zone for the generation of Love waves. (2) Apparent velocities of Love waves for periods between 6 and 9 s are concordant with the phase velocities of fundamental mode Love waves calculated from a threelayered model. The first, second, and third layers in the model have S-wave velocities of 0.5, 0.8, and 1.2 km/s, respectively. The S-wave velocity in the pre-Tertiary basement is assumed to be 2.6 km/s.
Liquid in a large piping system could become a resonance column under axial excitations. A 1000-m long closed-boundaries pipeline with pressure wave propagation velocity of 1000 m/s would have the fundamental liquid resonance frequency of 0.5 Hz. Then, some hydraulic transients might occur during strong earthquakes. If dynamic pressure amplitude exceeds the value of system stationary pressure, then vaporizing at negative pressure, and after that, cavity or liquid column separation and reconnection can be produced. One of the effects of these behaviors would be equivalent damping of dynamic response, and the other an impact force on pipe structural system. The latter effect is considered as one of potential damage factors of a large liquid piping system. In this paper, an analytical method of earthquake-induced hydraulic transients of piping system is applied to a real underground large piping system subjected to a strong earthquake motion which has occurred in Japan. The results of the analysis have shown that the occurrence of earthquake-induced negative pressure in liquid column is possible. Further, the analysis has explained the difference between two long straight pipelines buried in the same route, one failed by axial cracking and the other had no damages.
The largest three-dimensional shake table is now being constructed in Hyogo prefecture, Japan for a solution of fracturing process of structures, buildings, and soils. However, it seems to be difficult to measure the fracturing processes of the structures during severe earthquake by using conventional methods and equipment, because the three-dimensional measurement of larger dynamic displacement in excess of elastic region of the structure will be the key to a solution and cannot be obtained by any of the vibration pick-ups such as displacement transducers and so on. In this study, R&D of the new measurement method to clarify the fracturing process of the structures by applying a so-called motion capture technique, which has been mainly studied for modeling of human actions and motions. This paper describes the concept of the system, the outline of the proto-type image processing system developed in the study and the results of the shake table test using five-story steel-structure model to investigate the measurable accuracy of the system.
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