Preliminary evaluation of the rock-mass disturbance resulting from shaft, tunnel, or borehole excavation

Technical Report · Mon Nov 01 04:00:00 EST 1982

OSTI ID:6672554

Kelsall, P C; Case, J B; Chabannes, C R

The isolation of nuclear wastes in deep, mined repositories will require the sealing of all penetrations such as shafts, tunnels, or boreholes, into or nearby the repository. An important consideration in penetration sealing is the disturbed zone, or zone of increased permeability, which may be created in the rock mass adjacent to the penetration as a result of excavation. Disturbed zone characteristics for shafts, tunnels, and boreholes are evaluated by analysis and by review of previous laboratory and field tests. Consideration is given also to test methods for characterizing the disturbed zone in situ, and to methods for treating the disturbed zone in seal construction. Laboratory tests indicate that the disturbed zone associated with small-diameter boreholes is probably insignificant. In contrast, the disturbed zone is potentially a significant pathway for flow through seals placed in shafts and tunnels. Because a major mechanism for disturbance is believed to be stress relief acting across fractures, much of the disturbance occurs regardless of the excavation method used. Various test methods are proposed for disturbed zone characterization in shafts and tunnels, with seismic refraction identified as a promising index test. A proposed method for treating the disturbed zone uses cutoffs constructed as a series of overlapping boreholes. Each hole is filled with concrete which is allowed to cure before the adjacent holes are drilled.

• Research Organization: D'Appolonia Consulting Engineers, Albuquerque, NM (USA)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6672554
• Report Number(s): ONWI-411; ON: DE83004374
• Country of Publication: United States
• Language: English

Related Subjects

052002* -- Nuclear Fuels-- Waste Disposal & Storage
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
BOREHOLES
CAVITIES
GEOLOGIC DEPOSITS
MANAGEMENT
MATERIALS
MECHANICS
RADIOACTIVE WASTE DISPOSAL
ROCK MECHANICS
SEALING MATERIALS
SEALS
SHAFT EXCAVATIONS
TUNNELS
UNDERGROUND DISPOSAL
UNDERGROUND FACILITIES
WASTE DISPOSAL
WASTE MANAGEMENT