Influence of Compositional and Textural Changes by Weathering on Breakdown Property of Rocks

Influence of compositional and textural changes by weathering on breakdown property of rocks was considered through two cases.First case is the slaking property change of Poronai siltstone by preceding deteriorations such as weathering alteration and shear by landslide. The altered sample, where increase in smectite was observed, showed accelerating slaking behavior. In contrast, the sample, that was fractured by landslide but not altered, showed drastic slaking in the early stage of the slaking test and then approached to the behavior of intact sample.Second case is the influence of weathering on breakdown behavior in uniaxial compressive test. Samples are Inada granite and Kuroishiyama gabbro. In their weathered samples, fractures occurred by weathering were observed and their distributions had close relationships with the composition and texture of the plutonic rocks. Breakdown behaviors in the uniaxial compression were affected by the fractures developed through weathering.In these two cases, the breakdown behaviors are considered to relate with compositional and textural changes occurred by weathering, and it indicates that grasping about compositional and textural change is essential for understanding and prediction of physical property variation in weathering environment.