Numerical simulations of earthquake effects on tunnels for generic nuclear waste repositories

Technical Report · Mon Dec 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/6919549· OSTI ID:6919549

Wahi, K. K.; Trent, B. C.; Maxwell, D. E.; Pyke, R. M.; Young, C.; Ross-Brown, D. M.

The objectives of this generic study were to use numerical modeling techniques to determine under what conditions seismic waves generated by an earthquake might cause instability to an underground opening, or cause fracturing and joint movement that would lead to an increase in the permeability of the rock mass. Three different rock types (salt, granite, and shale) were considered as host media for the repository located at a depth of 600 meters. Special material models were developed to account for the nonlinear material behavior of each rock type. The sensitivity analysis included variations in the in situ stress ratio, joint geometry, pore pressures, and the presence or absence of a fault. Three different sets of earthquake motions were used to excite the rock mass. The calculations were performed using the STEALTH codes in a three-stage process. It was concluded that the methodology is suitable for studying the effects of earthquakes on underground openings. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass. A rock-burst tremor with accelerations up to 0.95 g, however, was found to be amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In shale, even moderate seismic loading resulted in tunnel collapse. Other questions appraised in the study include the stability of granite tunnels under various combinations of joint geometry and in situ stress states, and the overall stability of tunnels in shale subject to the thermomechanical loading conditions anticipated in an underground waste repository.

• Research Organization: Science Applications, Inc., Fort Collins, CO (USA)
• DOE Contract Number: AC09-76SR00001
• OSTI ID: 6919549
• Report Number(s): DP-1579
• Country of Publication: United States
• Language: English

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580201* -- Geophysics-- Seismology & Tectonics-- (1980-1989)
COMMINUTION
COMPUTER CODES
DATA
EARTHQUAKES
FRACTURING
GEOLOGIC DEPOSITS
GRANITES
IGNEOUS ROCKS
INFORMATION
MANAGEMENT
MATHEMATICAL MODELS
NUCLEAR FACILITIES
NUMERICAL DATA
PERMEABILITY
PLUTONIC ROCKS
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE FACILITIES
ROCKS
S CODES
SALT DEPOSITS
SEDIMENTARY ROCKS
SEISMIC EFFECTS
SEISMIC EVENTS
SENSITIVITY ANALYSIS
SHALES
SIMULATION
SPACE
STRAINS
TEMPERATURE EFFECTS
THEORETICAL DATA
TUNNELS
UNDERGROUND DISPOSAL
UNDERGROUND SPACE
WASTE DISPOSAL
WASTE MANAGEMENT