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Title: Strength and permeability tests on ultra-large Stripa granite core

Technical Report ·
DOI:https://doi.org/10.2172/5361784· OSTI ID:5361784

This report presents the results of laboratory tests on a 1 meter diameter by 2 meters high sample of granitic (quartz monzonite) rock from the Stripa mine in Sweden. The tests were designed to study the mechanical and hydraulic properties of the rock. Injection and withdrawal permeability tests were performed at several levels of axial stress using a borehole through the long axis of the core. The sample was pervasively fractured and its behavior under uniaxial compressive stress was very complicated. Its stress-strain behavior at low stresses was generally similar to that of small cores containing single healed fractures. However, this large core failed at a peak stress of 7.55 MPa, much less than the typical strength measured in small cores. The complex failure mechanism included a significant creep component. The sample was highly permeable, with flows-per-unit head ranging from 0.11 to 1.55 cm/sup 2//sec. Initial application of axial load caused a decrease in permeability, but this was followed by rapid increase in conductivity coincident with the failure of the core. The hydraulic regime in the fracture system was too intricate to be satisfactorily modeled by simple analogs based on the observed closure of the principal fractures. The test results contribute to the data base being compiled for the rock mass at the Stripa site, but their proper application will require synthesis of results from several laboratory and in situ test programs.

Research Organization:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
5361784
Report Number(s):
LBL-11203; SAC-31; ON: DE82012590; TRN: 82-015666
Resource Relation:
Other Information: Portions of document are illegible
Country of Publication:
United States
Language:
English