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A collapse doline in Wood Buffalo National Park Alberta, Canada
Abstract Flat-lying dolostones of the Devonian Keg River Formation form an escarpment about 30 m high, 30 km west of Fort Smith on the boundary of Alberta and the North West Territories of Canada. The dolostone is underlain by gypsum beds of the Devonian Chinchaga Formation. Gypsum solution causes numerous collapse dolines in the Keg River Formation. One doline, 45 m in diameter, has 15 m high, vertical walls of dolostone. We have applied 3 systems, developed to determine the support necessary for underground openings of a given span in a give rock mass, to the assessment of the natural opening beneath the doline. From the characteristics of the rock mass, a 15 m unsupported span in the formation can be expected to stand-up for about one month. We suggest that unsupported natural openings exist which are about three times larger than any we would design in the rock mass because:Underground opening design is conservative;Natural sethods of excavation cause less damage to the surrounding rock than artificial excavation methods; andNatural solution channels tend to form with their axes parallel to gaping joints. These gapes tend to close if substantial compressive stresses exist normal to the joints. Thus, the major axes of natural underground openings tend to parallel the largest compressive stresses in the rock mass, an arrangement which enhances the stability of the openings.
A collapse doline in Wood Buffalo National Park Alberta, Canada
Abstract Flat-lying dolostones of the Devonian Keg River Formation form an escarpment about 30 m high, 30 km west of Fort Smith on the boundary of Alberta and the North West Territories of Canada. The dolostone is underlain by gypsum beds of the Devonian Chinchaga Formation. Gypsum solution causes numerous collapse dolines in the Keg River Formation. One doline, 45 m in diameter, has 15 m high, vertical walls of dolostone. We have applied 3 systems, developed to determine the support necessary for underground openings of a given span in a give rock mass, to the assessment of the natural opening beneath the doline. From the characteristics of the rock mass, a 15 m unsupported span in the formation can be expected to stand-up for about one month. We suggest that unsupported natural openings exist which are about three times larger than any we would design in the rock mass because:Underground opening design is conservative;Natural sethods of excavation cause less damage to the surrounding rock than artificial excavation methods; andNatural solution channels tend to form with their axes parallel to gaping joints. These gapes tend to close if substantial compressive stresses exist normal to the joints. Thus, the major axes of natural underground openings tend to parallel the largest compressive stresses in the rock mass, an arrangement which enhances the stability of the openings.
A collapse doline in Wood Buffalo National Park Alberta, Canada
Cruden, D. M. (author) / Leung, Y. W. (author) / Thomson, S. (author)
1981
Article (Journal)
English
A collapse doline in Wood Buffalo National Park Alberta, Canada
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