Damage caused by long-term, gradual karstic subsidence

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6863165

Beck, B F; Jenkins, D T; Parker, J W

Damage due to karstic subsidence (sinkhole collapse) is generally presumed to be relatively rapid in human terms. However, during repaving of a runway apron at Mac Dill Air Force Base, Tampa, Florida, 41 shallow depressions were formed during proof rolling. The apron is underlain by 6-10 m of sand and clayey sand over the limestones of the Floridan Aquifer, which are known for their karst. The apron was originally paved in 1952. Ground penetrating radar revealed that a radar-reflecting boundary, circa 4-5 m below the surface, had also subsided in an inverted-conical pattern beneath the depressions, as well as in other areas. Beneath some of the areas the pavement subbase had also subsided similarly. VLF surveys over and around the depressions mapped a linear trend identical to the apparent alignment of the depressions. Close-spaced drilling confirmed that the subsidence was directly over a depression in the limestone surface. Further, the overlying sand had an N = 0-1, whereas the surrounding sand tested N = 4-6. The authors have concluded that gradual erosion of the overlying sand into karstic depressions and voids in the limestone over a 32 year period has reduced the sand density and strength and caused subsidence where the overlying pavement was loaded.

• Research Organization: Univ. of Central Florida, Orlando (USA)
• OSTI ID: 6863165
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580100 -- Geology & Hydrology-- (-1989)
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
AQUIFERS
BOREHOLES
CARBONATE ROCKS
CAVES
CAVITIES
DAMAGE
DISSOLUTION
DRILLING
ENGINEERING GEOLOGY
FEDERAL REGION IV
FLORIDA
GEOLOGY
GROUND SUBSIDENCE
LIMESTONE
NORTH AMERICA
ROCKS
SEDIMENTARY ROCKS
USA
WELL DRILLING