The phenomenon of liquefaction is one of the most important subjects in earthquake engineering. After introducing the general description on the liquefaction phenomenon, computer algorithms for liquefaction analyses of fluid-saturated grounds are summarized which use finite element and finite difference coupled numerical methods; the accuracy of several numerical methods are then addressed through comparisons of the analytical solutions and the experimental data as well as observed ground motions during the 1995 Hyogo-ken Nanbu earthquake. To estimate large ground displacement during and after the liquefaction occurrence a typical stress-strain relationship of sand after onset of liquefaction is discussed using the data obtained by torsional shear tests under several conditions.
As you know we had the great Hanshin Earthquake at early morning on Jan.17, 1995, so beautiful Kobe city was almost crumbled. This report is made on basis of a field investigation on almost all bridge structures located in the related area. By the inspection of damaged or collapsed bridges it is clear that a large number were designed more than 20 years ago, and also these structures had not retrofitted to increase their resistant capacity against large earthquakes. Finally, this earthquake showed more than ever, the effect of vertical acceleration like a shock on the failure mechanism of collapsed structures.
An interdisciplinary research activity, Science on Form, started in 1980. The society ‘Science on Form, Japan’ was established in 1984. In addition to three regular domestic symposium a year, it organized two International Symposiums of Science on Form, the 1st in 1985 and the 2nd in 1988 both in Tsukuba. It publishes three issues of the Journal Forma in English every year. It covers all fields of Science. The actual activities and some topics will be introduced in this report. In these years, some complimentaly societies are organized and the related activities grow more and more wide to include art. An International Symposium KATACHIU SYMMETRY was held in November 21-25, also in University of Tsukuba. It played a role of an international and cultural contribution from Japan with some view based on the background of our Japanese culture and was an enjoyable symposium.
A liquid transport system utilizing encapsulated liquid drops is developed. An experimental apparatus for the sequential production and the self-recovery of encapsulated drops is designed using effectively the functions of the buoyancy-driven motion and the breakdown phenomena of encapsulated drops in liquid-liquid-gas systems. As the first step to investigate the flow characteristics of encapsulated drops in the apparatus, the mean diameter, the shell thickness and the production frequency of encapsulated drops are measured for the wide range of the flow conditions and the liquid properties. The formation patterns and the behavior of encapsulated drops are also observed in detail. The results obtained here would provide the fundamental knowledge for designing the high performance heat and mass exchangers using liquid-liquid-gas systems.
Oxygen absorption rates into water were measured to determine volumetric mass transfer coefficients, kLa, in bubble and slug flow regimes of gas-liquid two-phase upflow through a 0.03m i.d. vertical tube. Axial local values of kLa decreased rapidly downstream from gas inlet. Axial averaged values of kLa, which is denoted by (kLa) z, were affected by gas velocity, uGO, liquid velocity, uLO, and distance from gas inlet, z, being correlated by the following equation:(kLa) z=0.38uGO0.69uLO0.33Z-0.27Moreover, the liquid-side mass transfer coefficients, kL, were calculated with the gas-liquid interfacial area obtained by the photographs of flow. The values of kL were correlated well with the energy dissipation rate, which was consistent with the eddy cell model.