Configuration and Roughness of Fractures for Gneiss by Varying stress state
| Autor: | Chi-Jie Lu Chang, 盧張其杰 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 The geometric roughness in rock mass fractures, this is the fact dominate rock mass deformation and damage and percolation percolation. Barton (1977) proposed joint roughness coefficient JRC value assess the degree of roughness of the fractures, existing JRC value evaluate methods most unilaterally determined with geometrically, the JRC and the anisotropy mechanical behavior of joint plane and size effects related research has been frequently reported, but researches regarding the geometric characteristics of fracturing’s under different stress state has seldom been considered. Focusing on rock mechanics laboratory test, this study not only conduct tensile splitting strength test, uniaxial compression test, and triaxial compression test, rock fractures obtained under different stress states, also discuss the impact of gneissosity and confining pressure on rock fracturing plane through changing gneissosity and maximum loading directions, in obtaining the same area different directions drilling core specimens. Use profilometer was constructed to measure the artificially fractures. Use of Tse &; Curden (1979) proposed empirical formula to obtain the value of the roughness coefficient JRC. Evaluate geometry of the fractures under different stress states. Experimental results reveal, which the fractures obtained by tensile splitting strength test under compression-tension stress state are planar .However, the wall of fractures are rough, exhibiting saw tooth fractures perpendicular to loading direction. The fractures from uniaxial compression stress state are irregular and the fracture walls are rough saw tooth fractures perpendicular to loading direction are also observable. Under triaxial compression stress state, the fractures change from irregular to regular as the confining pressure increases, and saw tooth fractures disappear in the meanwhile. In this study, in order improve fractures of sample describe methods and accuracy, the development central of a scanning device with improve fractures of sample describe methods and accuracy. Expand the image generated through crack occurrence and distribution of native discontinuities was portrayed. The results showed that native discontinuities and confining pressure for the crack generation capacity growth direction and angle having a significant impact. The results show, through profile on the fractures segmentation, after obtaining different trace length profile, using the JRC empirical formula calculate on each segment profiles, and by statistical analysis of the way to get in the rock fractures an average of JRC profiles of different sizes, and unfragmented JRC will not have much variation. Then measured by the amount of laser profiler fractures undulating under different stress states. The results show, rocks under different stress states fractures, its rough characteristics have differences. This study was to investigate the influence of native rock discontinuities, when a series of rock mechanics testing, adjusting the angle between the discontinuity and the external force is applied. Discussion native discontinuity effects on the relative orientation of rock fractures morphology and roughness characteristics. The results show, native discontinuities in the fractures morphology and roughness characteristics have an impact, with the stress state and external force is applied and discontinuities angle change. Maximum and minimum JRC with discontinuity strike and dip-direction will show vertical and parallel, or maximum and minimum JRC with discontinuity strike and dip-direction will an angle clip. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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