表面ひずみのマッピングによる岩石のクリープの研究

抄録

Surface strain mapping of Ohshima granite during the creep experiment shows that a uniformity of loading up to the creep setting stress was attained, and that a large change in strain field occurred during the early stage of transient creep. The change of the strain field represented the anisotropic development of dilatancy immediately after the creep initiation. The pattern of strain distribution established in this stage was rarely changed in the subsequent course of the creep. The accelerating increase noted in one of the circumferential strain gages during the tertiary creep documents a strong localized deformation before the main fracture. The clustering region of AE events during the tertiary creep, which was determined by the simultaneous measurement presented in the other paper, was close to the region where the strong localized deformation was observed in this surface strain mapping. The projection of AE hypocenters to the specimen surface revealed that the hypocenters of AE events during the creep were mostly located between the strain gages. This biasing was explained on the basis of the role of water vapor in stress corrosion cracking. The adhesion of strain gage prevents the transport of water vapor from the surface of specimen to the crack tip.