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

本研究旨在阐明地震作用下码头墙失稳的机理，阐明液化对沉箱与回填土地基相互作用的重要影响。通过对日本重力式码头墙在几次强震中造成的破坏的仔细调查，包括1995年的Hyogoken-Nambu地震，阐明了破坏的程度与回填土地基中液化的发生密切相关。抗液化处理后的码头墙可以在强震中幸存下来，几乎没有破坏，这与未处理的码头墙经常出现的严重破坏形成了鲜明的对比。然后，我们对模型码头墙进行了一系列模型振动台试验，重点研究了回填土地基液化的影响。根据回填土地基是否发生液化，沉箱的移动有很大的不同。波动的EART…在不发生液化的情况下，较大的h压力抑制了沉箱的移动。另一方面，当回填土地基发生液化时，由于土压力的波动分量与惯性力在相角上重合，使得沉箱的滑移加剧。在模型振动试验中，还仔细观察了作用于沉箱后壁液化过程中的脉动土压力。本文还对日本北海道久路港市重力式码头墙在地震作用下的动力行为进行了现场观测，旨在确认液化对码头墙破坏的决定性作用，为评估挡土结构的地震土压力和制定合理的重力式码头墙抗震设计方法提供依据。在2003年的东京大地震中，试验码头的围墙以V级地震烈度摇晃。通过对试验码头墙体的动力特性分析，揭示了液化对试验码头墙体变形的影响。较少

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