OBSERVATION OF THE SEISMIC BEHAVIOR OF GRAVITY TYPE QUAY WALL AND DEVELOPMENT OF ITS EARTHQUAKE RESISTANT DESIGN.

本研究旨在解释地震作用下码头岸壁失稳的机理，阐明液化对沉箱与回填土相互作用的重要影响。通过对1995年兵库县南部地震等几次日本强震中重力式码头岸壁的破坏情况进行深入调查，发现破坏程度与回填地基液化的发生密切相关。经过液化处理后的码头岸壁在强震作用下几乎不受破坏，与未经处理的码头岸壁的严重破坏形成了鲜明的对比。沉箱的运动被发现是相当不同的，这取决于是否液化发生在回填地面或没有。波动的大地 关于我们 当不发生液化时，作用在沉箱上的压力抑制了沉箱的移动。另一方面，当回填土发生液化时，由于土压力脉动分量与惯性力的相位角重合，沉箱的滑移加剧。在模型振动试验中，对液化过程中作用在沉箱后壁上的脉动土压力进行了细致的观测。本文还对日本北海道钏路港重力式岸壁结构在地震作用下的动力特性进行了现场观测，以确定液化对岸壁结构破坏的决定性作用，并对液化后岸壁结构的动力特性进行了分析。为评价挡土结构的地震土压力和建立重力式码头合理的抗震设计方法提供了依据。在2003年十胜冲地震中，试验码头的岸壁发生了地震烈度为V+级的震动。通过对试验岸壁实测动力特性的分析，揭示了液化对试验岸壁变形的影响。少

This research project was conducted aiming to explain the mechanism of the instability of quay wall induced by earthquake, and clarify the significant influence of liquefaction on the interaction between the caisson and the backfill ground. The close investigation of the damage to gravity type of quay walls caused in several strong earthquakes in Japan including the 1995 Hyogoken-nambu Earthquake, clarified that the degree of damage was strongly related to the occurrence of liquefaction in the backfill ground. The treated quay walls against liquefaction could survive the strong earthquakes with little or no damage, in marked contrast to the severe damage frequently seen in untreated quay walls.Then, we conducted some series of model shaking table tests on model quay walls focusing on the effect of liquefaction in the backfill ground. The movement of the caisson was found to be quite different depending on whether liquefaction occurred in the backfill ground or not. The fluctuating eart … More h pressure on the caisson suppressed the movement of the caisson when liquefaction did not occur. On the other hand, sliding of the caisson was enhanced since the fluctuating component of earth pressure and the inertial force coincide in phase angle, when liquefaction occurred in the backfill ground. The fluctuating earth pressure acting on the back wall of the caisson in the process to liquefaction was also carefully observed in the model shaking tests. This suggested that stability criteria of the caisson should be developed not by the onset of the liquefaction but by the sudden phase change.We also conducted a field observation of dynamic behavior of full-scaled test gravity type of quay wall during earthquakes in the Port of Kushiro, Hokkaido, Japan, aiming to confirm the decisive effect of the liquefaction on the damage to quay wall, and provide information for the evaluation of seismic earth pressure on retaining structure and the development of rational earthquake resistant design method for gravity type quay wall. In the 2003 Tokachi-oki Earthquake, the test quay wall was shook with the seismic intensity of rank V+. The analysis of the observed dynamic behavior the test quay wall showed the effect of the liquefaction on the deformation of the test quay wall. Less