Thermomechanical effects on permeability for a 3-D model of YM rock

摘要

The authors estimate how thermomechanical processes affect the spatial211u001evariability of fracture permeability for a 3-D model representing Topopah Spring 211u001etuff at the nuclear-waste repository horizon in Yucca Mountain, Nevada. Using a 211u001efinite-difference code, they compute thermal stress changes. They evaluate 211u001epossible permeability enhancement resulting from shear slip along various mapped 211u001efracture sets after 50 years of heating, for rock in the near-field environment 211u001eof the proposed repository. The results indicate permeability enhancement of a 211u001efactor of 2 for regions about 10 to 30 m above drifts, for north-south striking 211u001evertical fractures. Shear slip and permeability increases of a factor of 4 can 211u001eoccur in regions just above drifts, for east-west striking vertical fractures. 211u001eInformation on how permeability may change over the lifetime of a geologic 211u001erepository is important to the prediction and evaluation of repository 211u001eperformance.