Analysis of slope stability, Wilmington to Lindenkohl Canyons, US mid-Atlantic margin
Conference
·
OSTI ID:6333351
The continental slope gradient in the study area averages 7 to 8/sup 0/. Many valleys, canyons, and occasionally large sediment slumped masses occur. Moderate to steep slopes (19 to 27/sup 0/) as well as very steep to precipitous slopes (> 27/sup 0/) are abundant and occupy about 7% of the investigated area. The surficial sediments are predominantly terrigenous silty clays of medium to high plasticity (I/sub p/ = 10 to 35% w/sub L/ = 30 to 70%), but contain varying quantities of sands. Angles of internal friction are anti phi/sub d/ = 27 to 32/sup 0/, anti phi/sub cu/ = 30 to 33/sup 0/, and phi/sub cu/ = 14 to 17/sup 0/. The sediments are normally to slightly overconsolidated, but some unconsolidated sediments also were identified. c/sub u//anti p/sub 0/ values range from 0.12 to 0.78. An analysis of force equilibrium within the sediments reveals that (a) the gentle slopes in the study area are mostly stable; (b) that the stability of some steep slopes (19 to 27/sup 0/) is marginal; and (c) that on precipitous slopes (> 27/sup 0/) only a thin veneer of sediments can exist. Observations of these slopes during steep dives support these results. The analysis shows that additional accumulation of sediments and small shocks caused by earthquakes or internal waves can cause the slopes to fail. Collapse resulting from liquefaction in the uppermost slope along the canyons and valley axes, where fine sands and silt accumulate, also is likely. 22 references, 9 figures, 2 tables.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA); Geological Survey of Israel, Jerusalem. Marine Geology and Geomathematics Div.; Naval Ocean Research and Development Activity, NSTL, MS (USA). Seafloor Geosciences Div.; National Oceanic and Atmospheric Administration, Miami, FL (USA). Atlantic Oceanographic and Meteorological Labs.
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 6333351
- Report Number(s):
- SAND-84-1015C; CONF-841217-1; ON: DE84012278
- Country of Publication:
- United States
- Language:
- English
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