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Physical Hydrogeological Modeling of Florida's Sinkhole Hazard
Title
Physical Hydrogeological Modeling of Florida's Sinkhole Hazard.
Creator
Perez, Adam, Nam, Boo Hyun, Wang, Dingbao, Chopra, Manoj, Singh, Arvind, An, Jin Woo, University of Central Florida
Abstract / Description
Sinkholes are one of the major geohazards in karst terrain and pose a social, economic, and environmental risk. In Florida, sinkhole-related insurance claims between 2006 and the third quarter of 2010 amounted to $1.4 billion. Approximately 20 % of the United States is underlain by karst terrain formed from the dissolution of soluble rocks and is susceptible to a sinkhole hazard. Particularly, Texas, Florida, Tennessee, Alabama, Missouri, Kentucky, and Pennsylvania are known as sinkhole...
Show moreSinkholes are one of the major geohazards in karst terrain and pose a social, economic, and environmental risk. In Florida, sinkhole-related insurance claims between 2006 and the third quarter of 2010 amounted to $1.4 billion. Approximately 20 % of the United States is underlain by karst terrain formed from the dissolution of soluble rocks and is susceptible to a sinkhole hazard. Particularly, Texas, Florida, Tennessee, Alabama, Missouri, Kentucky, and Pennsylvania are known as sinkhole states.The scope of this study is to develop a physical model to simulate sinkholes (referred to as a sinkhole simulator), which can assess the qualitative behavior of the hydrogeological mechanism of Florida's sinkhole formations. Two sinkhole simulators were developed, with the second simulator constructed to overcoming the limitations of the first. The first generation sinkhole simulator incorporated a falling head groundwater system and the sinkhole could only be observed once the ground surface was breached. The second generation sinkhole simulator incorporated a constant head groundwater system which accurately depicts field conditions and the sinkhole was able to be observed during all stages of formation within this model. In both simulators multiple hydrogeological conditions were created and water level transducers were installed at various locations within the soil profile to monitor variations in the groundwater table during the sinkhole process, this was done to investigate the soil-groundwater behavior.Findings from this study include: 1) groundwater recharge is a critical sinkhole triggering factor, 2) the groundwater table cone of depression increases as the raveled zone or void travels up through the overburden due to sinkhole formation, 3) The cover-subsidence sinkhole failure mechanism is similar to the failure mechanism present in Terzaghi's trapdoor experiment and the cover-collapse failure mechanism consists of four district components: failure planes with erosion envelope, arch dropout failure, formation of elliptical void, and slope stability failure, and 4) a strong qualitative relationship between soil strength and type of sinkhole formed (cover-subsidence or cover-collapse) was observed.
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Date Issued
2017
Identifier
CFE0006637, ucf:51247
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006637
Characterization of Waste-To-Energy (WTE) Bottom and Fly Ashes in Cementitious Materials
Title
Characterization of Waste-To-Energy (WTE) Bottom and Fly Ashes in Cementitious Materials.
Creator
An, Jin Woo, Nam, Boo Hyun, Yun, Hae-Bum, Chopra, Manoj, An, Linan, University of Central Florida
Abstract / Description
Waste-to-Energy (WTE) ashes (or called as municipal solid waste incineration ashes) have been recycled in the areas of road bed, asphalt paving, and concrete products in many European and Asian countries. In those countries, recycling programs (including required physical properties and environmental criteria) of ash residue management have been developed so as to encourage and enforce the reuse for WTE ashes instead of landfill disposal. However, the U.S. has shown a lack of consistent and...
Show moreWaste-to-Energy (WTE) ashes (or called as municipal solid waste incineration ashes) have been recycled in the areas of road bed, asphalt paving, and concrete products in many European and Asian countries. In those countries, recycling programs (including required physical properties and environmental criteria) of ash residue management have been developed so as to encourage and enforce the reuse for WTE ashes instead of landfill disposal. However, the U.S. has shown a lack of consistent and effective management plans as well as environmental regulations for the use of WTE ashes. Many previous studies demonstrated the potential beneficial use of WTE ash as an engineering material with minimum environmental impacts. Due to persistent uncertainty of engineering properties and inconsistency in the Federal and State regulations in the U.S., the recycling of WTE ash has been hindered, and they are mostly disposed of in landfills. The goal of this study is to identify beneficial use of WTE ashes as construction materials; thus, the recycling program of WTE ashes will become more active in the U.S. One of potential applications for the WTE ashes can be cement-based materials because the ashes contain good chemical components such as calcium and silicon. Moreover, toxics (heavy metals) can be bound or encapsulated in cement matrix; thus, the leaching potential can be reduced. The specific objectives are: (1) to understand the current practice of the reuse of WTE ashes as construction materials, (2) to physically and chemically characterize WTE bottom and fly ashes, (3) to investigate the effects of WTE bottom and fly ashes in cementitious materials (e.g. cement paste and concrete) as replacement of either cement of fine aggregate with emphasis on cement hydration, and (4) to investigate the environmental impacts of WTE bottom ash on leaching when used in cement-based materials. Fundamental properties of MSWI bottom ash and fly ash were studied by conducting physical, microstructural, and chemical tests. Petrographic examinations, such as scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and x-ray diffraction (XRD) were performed in order to identify chemical composition of the ash and to determine their contents. To evaluate the main side effect of ash when used in concrete, the creation of a network of bubbles due to the presence of aluminum, ashes and aluminum powder were submerged in high pH solution, and the evolution of hydrogen gas was measured. Efforts were made to investigate the influence of WTE ashes on engineering properties of cement paste and concrete specimens when part of Portland cement and fine aggregate are replaced with ground and sieved WTE ashes. Cement paste and concrete cylinders were cast with various amounts of mineral and fine aggregate additions, respectively, and their strength and durability were investigated. Subsequently, optimum mix proportioning of the WTE ashes was investigated when they are used in cement paste and concrete specimens. In addition, the leaching characteristics of major alkaline and trace elements from concrete containing varied amounts (10%-50%) of BA were investigated by Synthetic Precipitation Leaching Procedure (SPLP) batch testing.
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Date Issued
2015
Identifier
CFE0006251, ucf:51070
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006251
Use of Accelerated Calcite Precipitation Method to Investigate Calcium Carbonate Precipitation from Recycled Concrete for Drainage System Applications
Title
Use of Accelerated Calcite Precipitation Method to Investigate Calcium Carbonate Precipitation from Recycled Concrete for Drainage System Applications.
Creator
McCulloch, Toni, Nam, Boo Hyun, Chopra, Manoj, Arboleda Monsalve, Luis, An, Jin Woo, Filler, Dennis, University of Central Florida
Abstract / Description
Recycled concrete aggregate (RCA) is a sustainable construction material that is a viable option for use in drainage systems by replacing virgin aggregate. Replacing virgin aggregate with RCA is beneficial from both economic and environmental perspectives. However, the use of RCA as pipe backfill materials may cause a long-term performance issue such as potential clogging due to fines accumulation and calcite precipitation on filter fabric. Previous studies investigated the long-term...
Show moreRecycled concrete aggregate (RCA) is a sustainable construction material that is a viable option for use in drainage systems by replacing virgin aggregate. Replacing virgin aggregate with RCA is beneficial from both economic and environmental perspectives. However, the use of RCA as pipe backfill materials may cause a long-term performance issue such as potential clogging due to fines accumulation and calcite precipitation on filter fabric. Previous studies investigated the long-term performance of RCA regarding flow rate. Therefore, this study investigated calcite precipitation potential of RCA. The Accelerated Calcite Precipitation (ACP) procedure was devised and used to estimate (")life-time(") calcite precipitation of RCA for French Drains. The ACP procedure was studied further and improved to optimize the calcite precipitation procedure. The enhanced method was used to compare the calcite precipitation of limestone and RCA samples - sources with varying chemistry and history. Key findings are (1) the clogging due to calcite precipitation of RCA is not as significant as clogging due to the existing and/or accumulated fines, (2) the calcite precipitation can be increased with a temperature of 75(&)deg;C and 17-hour heating time, and (3) the potential for calcite precipitation from RCA is not as significant as limestone for Type I underdrain gradation.
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Date Issued
2018
Identifier
CFE0007321, ucf:52132
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007321