In Japan, a slip safety factor based on an equivalent linear analysis is conventionally used to evaluate the stability of rock foundations under critical facilities in terms of the sliding motion during an earthquake. In this study, dynamic centrifugal model tests were performed to assess the seismic stability evaluation method for rock foundations. The results confirmed the feasibility of the method. In addition, the displacement of rock masses because of sliding was observed to be limited even when the slip safety factor had a value of less than 1. This confirms that, in the event of an earthquake, rock foundations do not become unstable spontaneously. Therefore, evaluating the seismic stability based on ground displacement is considered to be an effective approach.
The occurrence of fatal and large-magnitude earth-quakes in the recent past has increased attention on considering earthquake ground motions during the design phase of the construction of modern structures. Accordingly, the quantitative assessment of the seismic resistance of critical facilities to the earthquake-induced failure of rock foundations has become important.
In Japan, the seismic stability of rock foundations has conventionally been evaluated in terms of their bearing capacity, inclination, and sliding (JEAG 4601-1987 1987). With regard to the sliding motion during an earthquake, a slip safety factor based on an equivalent linear analysis is conventionally used to evaluate the stability of rock foundations. However, a slip safety factor value of less than 1 does not necessarily indicate immediate ground instability.
In this study, therefore, dynamic centrifugal model tests were performed to assess the applicability of conventional slip safety factor evaluation methods to the seismic stability of rock foundations.
A rock foundation model with a reduction ratio of 1:50 was constructed with artificial rock material and a weak layer. Vibration tests were performed in a centrifugal force field under a centrifugal acceleration of 50 g.