Florida might be one of the most sinkhole-active areas on the earth. Due to its unpredictability and significance of occurrence, the development of sinkhole monitoring techniques is imperative to minimize sinkhole-induced hazards. Several methods have been used to evaluate sinkhole risks, including destructive methods, such as Standard Penetrating Tests (SPT) and Cone Penetrating Tests (CPT), geophysical method, and sensor-based groundwater monitoring method. However, few studies are available for comprehensive understanding of spatiotemporal sinkhole mechanism by combining different exploration methods under realistic experimental conditions. The objective of this study is to understand spatiotemporal sinkhole mechanism, using SPT, CPT, ground penetrating radar (GPR), and piezo pressure sensors tested at actual sinkhole sites. A small-scale test was conducted prior to the field test to validate data analysis technique using piezo pressure sensors, developed in this study. Eight piezo pressure sensors were used located at different distances from the sinkhole center to measure the ground water levels (GWLs) during artificially made sinkhole events. A total of 24 scaled tests was conducted with different sinkhole soil thickness and initial GWL. The cone of water depression was observed during the tests, which indicates there are strong relationship between sinkhole and sinkhole occurrence. A novel peak-counting method was developed and validated to estimate spatiotemporal relations of the relations between GWLs and sinkhole collapse patterns.The field test was conducted at an active sinkhole site in Lake county, Florida to determine locations of points of breach and to monitor fluctuation GWL over time. Twenty piezometer sensors were installed, and the GWLs were monitored for three months at 30-min sampling rate. The daily moving average of GWL was calculated and visualized in ArcGIS map to understand spatiotemporal behavior of GWL at different locations from sinkhole positions. The monitoring results were compared with CPT, SPT and GPR results that were conducted prior to the piezo sensor installations. Strong correlations were observed between CPT, SPT, GPR and GWL results. From the results, it can be concluded that size and shape of the cone of water depression depend on dimensions of point discharges and properties of surrounding soil.
| Identifer | oai:union.ndltd.org:ucf.edu/oai:stars.library.ucf.edu:etd-6236 |
| Date | 01 January 2016 |
| Creators | Tu, Ton |
| Publisher | STARS |
| Source Sets | University of Central Florida |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses and Dissertations |
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