摘要：

The aseismic foundation system, as described in this paper, is a new development, which makes it possible to build standard nuclear power stations in areas exposed to strong earthquakes. The principle consists in interposing a device between the buildings of the nuclear island and the foundation soil which limits the value of the horizontal acceleration in the nuclear island buildings. The nuclear island foundations consists of a double raft with aseismic bearings interposed between the upper and lower raft. These bearings are placed on top of short concrete pedestals constructed on the lower raft. The space thus provided between the two rafts allows access to the bearings. The bearing consists of two parts: a block of reinforced elastomer, a set of friction plates such as stainless steel+bronze with lead. The reinforced neoprene pad acts as a soft horizontal spring imparting a first mode of translation to the structure with the frequency of about 1 c.p.s. depending only on the characteristics of the bearing. As this first mode is predominant, the value of horizontal accelerations at each level for all buildings are almost identical. The above mentioned frequency has been selected in order to be outside the range of natural frequencies of the buildings themselves and of the frequency of the equipment. The friction plates due to their nature and surface treatment permit to ensure a consistent value of the coefficient of friction 'f' so as to limit the maximum horizontal earthquake forces to values close to fxg. Under a low level earthquake (0.15 g-0.20 g) the structure vibrates and returns to its original position. The temporary relative displacement during such an earthquake can reach about 0.10 m. Under an earthquake of higher level (up to 0.60 g) the vibrating structure slides on the friction plates. The complete detailed design together with experimental evidence have shown that the system is operational

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