2006 年 55 巻 5 号 p. 515-522
A large scale rock slope failure, with an estimated collapse volume of 2,700,000m3, occurred at a site where the deformational behavior had been monitored over several years. The characteristics of the behavior were in that the deformation was recorded not only during excavation of the slope, but also between excavations. This paper presents a summary of an investigation on the deformational mechanism both during and between excavations. In particular, a finite element procedure used herein has introduced a new method of modeling deformation between excavations as that associated with a reduction of material strength parameters. The results of this investigation suggest that a sign of a large scale collapse might have been seen in a relatively early stage of the slope excavation procedure.