高速高圧リングせん断試験機による地附山地すべり・御岳大崩壊の土質特性

Abstract

Soil Characteristics of the Jizukiyama Landslide and the Ontake Debris Avalanche wereexamined in use of a newly developed High-Speed High-Stress Ring Shear Apparatus.Glass beads were also tested for comparison with them.This paper mainly presents following results. That is:1) The friction angle tends to begreater when shearing speed becomes greater, for both of the Jizukiyama and the Ontakesample. For glass beads, however, the friction angle comes to be smaller. 2) No effect onthe friction angle by normal stress was recognized in the whole range of 0-about 3.5kgf/cm2. 3) When increasing normal stress on a saturated sample of the Jizukiyama soil, excess pore-pressure was generated, and it took so long time to dissipate. It is caused byvery small permeability of the Jizukiyama soil. While the Ontake soil did not generate suchexcess porepressure during the usual procedure to increase normal stress, because of theirhigh permeability.