A series of unique plate loading tests have recently been conducted by Sandia National Labo- ratories in welded tuff, at the Yucca Mountain Project Exploratory Studies Facility at Yucca Mountain, Ne- vada. The welded tuffs of Yucca Mountain are being considered by the United States Department of Energy as potential host media for the emplacement of high level nuclear waste. This paper describes the design and conduct of the in situ tests, and compares results with pre- and post-test elastic analyses.
The welded tuffs of Yucca Mountain, Nevada are being considered by the United States Department of Energy (DOE) as potential host media for the stor- age of high level waste (HLW). As part of the site characterization efforts for the Yucca Mountain Project (YMP), a mechanically excavated Explora- tory Studies Facility (ESF) was completed in 1997 (Fig. 1). A Thermal Testing Facility (TrF), subse- quently constructed off the main drift of the ESF, included the Single Heater Test block and the Drift Scale Test (DST). The DST is a multi-year thermal test being conducted in a 50-m long, 5-m diameter Heated Drift (HD). To determine potential changes in the rock mass modulus resulting from thermally induced closure of the fractures, a plate loading niche was constructed near the DST such that one side of the niche would be near ambient temperature and the other side was heated to >100°C.
Determination of rock mass modulus, a parameter of significance to the Yucca Mountain geomechan- ics program, is calculated using data gathered from the Plate Loading Test (PLT). It will be used in nu- merical analysis of drift stability, ground support interactions, and drift and repository behavior. Rock mass modulus may also be used in the coupling of the thermal and thermal-mechanical-hydrological- chemical (T-M-H-C) models used for the proposed repository.
