Coupled Nondestructive Techniques to Study the Macro and Micro Fracture Behavior of Rock-like Material under Inclined Shear Tests
| Autor: | Sin-Liang LIOU, 劉信良 |
|---|---|
| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 This research investigated the mechanism of shear failure by performing a series of tests together with measurements of ESPI and AE. To couple the nondestructive technique of ESPI and AE, a set of inclined shear test equipment was designed and built. Gypsum and gypsum-sand mixture were used to prepare the specimens. Four major topics were investigated in this research: (1) the correctness and suitability of the inclined shear device, (2) the dilatancy angle of the specimen, (3) the influence of particle size on the shear failure mode, (4) the timing of crack initiation investigated by ESPI. By comparisons of the results of inclined shear tests with direct shear tests, it is shown that both tests give similar strength parameters under the condition of normal stress less than 4MPa. The correctness and suitability of the inclined shear device was approved. The dilatancy angle is about 11 degrees for specimen of gypsum-sand mixture. The failure mode evolved from tension to shear failure as the normal stress decreased. Similar behavior was also observed from the results of numerical analysis. The crack initiation, observed by ESPI, occurred at about the same loading level for same material. For gypsum-sand mixture, the crack initiation occurred at about 82~86% loading level. The development and evolution of microcracks of the specimens could be studied by AE technique. By coupling the nondestructive technique of ESPI and AE, the evolution of microcracks and the mechanism of shear failure could be studied more thoroughly, and the results could be referred to the construction practice. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
| Externí odkaz: |
|