Change in Behavior of Uniaxial Compression due to Degradation of Salt Water and Freezing and Thawing for Rock
Kiyohito YAMAMOTO, Akira KOBAYASHI and Shigeyasu AOYAMA
Abstract:To investigate the effect of the degradation on the mechanical behavior, the degraded rock samples were prepared to the uniaxial compression test. The degradation methods are divided into two types. One type is submerged in the 10 % saline water (10%NaCl) for 90 days, and another one is freezing and thawing for 240 cycles. The degraded Smaland-granites were preserved in saline water. Kuri-hashi-granodiorite, Tage-tuff and Funyu-tuff were imposed on freezing and thawing test to make degraded state. The damage parame-ters were identified from the stress-strain relation obtained from the uniaxial compression tests. The damage parameters are K, n, Kd, nd and B0. K and n are related to expansive strain. Kd, nd and B0 are subject to behavior of Youngfs modulus. By investigating the change in the damage parameters of the degraded rock, the effect of the degradation was tried to infer. As the results, it was inferred using the damage parameters that the Smaland-granite becomes more expansive material and the damage occurs earlier due to saline water degradation. Moreover, it was considered that the Kurihashi-granodiorite and Tage-tuff become more expansive and the axial strain at the failure decreases by freezing and thawing degradation, however the axial strain of the Funyu-tuff at the failure becomes large. It was found the proposed damage parameters can be good index for volumetric strain behavior after degradation. Key Words:Rock, Damage mechanics, Salt water, Freezing and thawing, Degradation, Uniaxial compression test