Sinkhole confining breach, Sinkholes


Dynamic forces in the hydrologic cycle move underground water through Florida's carbonate rocks dissolving chemical components of the rocks, leaving behind caves, solution pipes, and other voids that result in a karst terrain. Ravelling is the common subsidence mechanism throughout most of Florida where unconsolidated materials filter downward into voids in the underlying limestone. A cavity in the overburden develops and enlarges over a period of many years. The enlarged cavity is also known as sinkhole. The investigations of sinkhole characteristics and potential involve studying the regional geology, hydrology and mapping historic sinkholes that have occurred in the area. Use of Cone Penetration Test (CPT) soundings, in conjunction with conventional soil borings are becoming more common in the assessment of subsurface soil conditions in the vicinity of sinkhole-related ground surface. The penetration resistance data by CPT can determine the presence and extent of raveled soil zones characteristic of sinkhole features, and the penetration pore water pressure data can be used to determine the integrity of the clay confining unit at each test sounding location. The objective of this study is to identify the possible location of the confining breach at a sinkhole in Seminole County. The methods used in the assessment of the sinkhole's subsurface conditions were Standard Penetration Test (SPT), which provided information that helped to identify the location of the ravelled zones within the soil profile, and Cone Penetration Test that gave information of the piezometric water levels obtained from the pore pressure dissipation curves. The total head was calculated from the piezometric water levels corresponding to the different elevations. The data were found to exhibit a downward behavior of the total head, starting at around elevation 50 feet, NGVD that extended towards lower elevations. The SPT boring log identified a ravelled zone starting at 31 feet approximately. From both information it was possible to establish that the hydraulic head was influenced by the proximity of the ravelled zones, where the head precipitated rapidly as the elevation decreased. From the result of this study, it was concluded that the location of the breach in the confining layer started at 61.8 feet deep below the ground surface. Potentiometric contour lines at elevation 24.40 feet denoted flow patterns of water from the surroundings of the depression towards the approximate location of the center, which is the existing of subsurface cavity.


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Graduation Date





Kuo, Shiou-San


Master of Science (M.S.)


College of Engineering and Computer Science


Civil and Environmental Engineering

Degree Program

Civil and Environmental Engineering








Release Date

May 2004

Length of Campus-only Access


Access Status

Masters Thesis (Open Access)


Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic