Preliminary analyses of the excavation investigation experiments proposed for the exploratory shaft at Yucca Mountain, Nevada Test Site

The Yucca Mountain Project (YMP), is examining the feasibility of siting a repository for high-level nuclear waste at Yucca Mountain on and adjacent to the Nevada Test Site. Three excavation experiments, Shaft Convergence, Demonstration Breakout Rooms, and Sequential Drift Mining, will provide some of the data required to (1) assess the mechanical behavior of repository-size openings and (2) validate numerical models that may be used in the repository design process. In this report, the results of preliminary analyses of the three excavation experiments are presented. The major objective of these analyses was to provide some guidance to the experiment planners regarding the expected displacements and stresses near the experimental drifts so that selection and placement of instrumentation could be optimized. Further, successful completion of these analyses demonstrates the ability to model the experiments, given the simplifying assumptions presented. Limitations of the analyses performed and the experiments as currently designed are also discussed. Finally, the results of these analyses provided some indication of how the variation of some key geometric and material parameters would affect the predicted results. Once the experiment design is finalized and site-specific material data are collected, pretest predictive analyses will be conducted using the mechanical and material models that require validation. 15 refs., 123 figs., 13 tabs