Micromechanical modeling tuffaceous rock for application in underground nuclear waste storage
- Univ. of Arizona, Tucson (United States)
Yucca Mountain, Nevada, is currently being considered as a potential site for the underground storage of high-level civilian radioactive wastes. The host rock surrounding the underground repository is Topopah Spring tuff. Previous experimental studies on tuffs have shown that pores are the primary microstructures of Topopah Spring and Apache Leap tuffs (an analog of for Topopah Spring tuff). Tuff is a kind of volcanic ash that has been compressed at high temperature, and pores have been found widely distributed in tuffs. The pores often appear to form at grain boundaries, and are considered an important flaw in initiating microcrack growth. Under compressive loading, microcracking will initiate from sharp corners of the pores and propagate subparallel to the maximum stress direction until interacting with other pores. Further loading may induce pore collapse which is a major contributor to rock deformation and dilatancy in Apache Leap tuff. Large macroscopic fractures in tuff are formed by the processes of crack growth, interaction, and pore linking. The linking crack is almost parallel to the maximum stress direction. The distance between pores in Topopah Spring tuff is 4-6 times the pore diameter. Detailed SEM observations indicate that macroscopic cracks tend to propagate along the path with the highest pore concentrations. Based on the specific micro-mechanisms for deformation in tuffs as described above, micromechanical models have ben developed. The next section of this paper describes these micromechanical models. The third section of the paper describes the use of these models to predict nonlinear rock deformation and failure in tuff under compressive stresses.
- Research Organization:
- Wisconsin Univ., Madison, WI (United States)
- OSTI ID:
- 145464
- Report Number(s):
- DOE/ER/14352--1; CONF-930644--Vol.2; ON: DE94014602
- Country of Publication:
- United States
- Language:
- English
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