A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Mine-by experiment committee report phase 1: excavation response summary and implications
The first phase of the Mine-by Experiment, i.e., excavation of a 3.5-m-diameter tunnel, was carried out at the 420 Level of the Underground Research Laboratory to investigate rock mass damage and progressive failure around a circular opening in brittle unfractured Lac du Bonnet granite. The tunnel was excavated without explosives, and state-of-the-art instrumentation comprising both geomechanical and geophysical instruments was used to monitor the failure process. The experiment showed that rock mass damage begins once the deviatoric stress (0'1 - 0'3) near the advancing face of the tunnel exceeds a critical level. Within the damaged zone, stabbing (a typical form of brittle failure) began at stress levels equivalent to about 50% of the short-term laboratory unconfined compressive strength. This reduction in strength between laboratory and in situ conditions occurs because the in situ loading path is far more complex than the monotonic loading path used to test laboratory samples. There is no evidence to suggest that the stabbing failure process would extend beyond the depth of damage defined by the deviatoric stress criterion. The stabbing process stops when the tunnel face has advanced sufficiently (approximately 2 tunnel diameters) such that the rock mass is no longer subjected to excavation-induced stress changes. (author). (Abstract Truncated) (Atomindex citation 28:073150)
Mine-by experiment committee report phase 1: excavation response summary and implications
The first phase of the Mine-by Experiment, i.e., excavation of a 3.5-m-diameter tunnel, was carried out at the 420 Level of the Underground Research Laboratory to investigate rock mass damage and progressive failure around a circular opening in brittle unfractured Lac du Bonnet granite. The tunnel was excavated without explosives, and state-of-the-art instrumentation comprising both geomechanical and geophysical instruments was used to monitor the failure process. The experiment showed that rock mass damage begins once the deviatoric stress (0'1 - 0'3) near the advancing face of the tunnel exceeds a critical level. Within the damaged zone, stabbing (a typical form of brittle failure) began at stress levels equivalent to about 50% of the short-term laboratory unconfined compressive strength. This reduction in strength between laboratory and in situ conditions occurs because the in situ loading path is far more complex than the monotonic loading path used to test laboratory samples. There is no evidence to suggest that the stabbing failure process would extend beyond the depth of damage defined by the deviatoric stress criterion. The stabbing process stops when the tunnel face has advanced sufficiently (approximately 2 tunnel diameters) such that the rock mass is no longer subjected to excavation-induced stress changes. (author). (Abstract Truncated) (Atomindex citation 28:073150)
Mine-by experiment committee report phase 1: excavation response summary and implications
C. D. Martin (author) / P. K. Kaiser (author)
1996
61 pages
Report
No indication
English
Geology & Geophysics , Soil & Rock Mechanics , Radioactive Wastes & Radioactivity , Radiation Shielding, Protection, & Safety , Excavation , Tunneling , Underground Disposal , Geologic Fractures , Plutonic Rocks , Response Functions , Stability , Stress Intensity Factors , Canada , Underground Mining , WNRE , Foreign technology , EDB/540250