Abstract
Analytical studies were carried out on the fractuations of the minimaum sliding safety factors of the the foundation ground and surrounding slope of nuclear power stations at various combinations of the horizontal and vertical earthquake motions. The range of the combinations were determined from the investigations on the phase deference between horizontal and vertical motions actually recorded at the rock sites. It was revealed that the fluctuations of the minimum sliding safety factors were not seriously affected by the phase differences between them.
Furthermore, fundamental studies on the damping and stiffness (bulk modulus) of the ground are conducted in order to more reasonably analyse the ground response by employing the equivalent linear analysis method with dynamic horizontal and vertical input motion.
