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- Title
- EFFECT OF HORIZONTAL PILES ON THE SOIL BEARING CAPACITY FOR CIRCULAR FOOTING ABOVE CAVITY.
- Creator
-
Arosemena, Rafael, Kuo, Shiou-San, University of Central Florida
- Abstract / Description
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The design of foundation in normal soil conditions is governed by bearing capacity, minimum depth of foundation and settlement. However, foundation design in karst regions needs to consider an additional criterion associated to the possibility of subsurface subsidence and ravelling sinkholes. Under this environment, alternative techniques are needed to improve the subsurface soil. In this study general background information is given to understand the geological characteristics of Central...
Show moreThe design of foundation in normal soil conditions is governed by bearing capacity, minimum depth of foundation and settlement. However, foundation design in karst regions needs to consider an additional criterion associated to the possibility of subsurface subsidence and ravelling sinkholes. Under this environment, alternative techniques are needed to improve the subsurface soil. In this study general background information is given to understand the geological characteristics of Central Florida and why this area is considered to be a karst region and susceptible to sinkholes formation. Traditional foundation design techniques on karst regions are addressed in this paper. Finally, the use of a network of three subsurface horizontal piles is proposed and the effect on stress increase and soil bearing capacity for footing due to the horizontal piles is investigated. Finite element computer software is used to analyze the stress distribution under different conditions and the results are discussed. The objective of this study is to determine whether or not horizontal piles under a circular footing at the sinkhole site is a viable solution to reduce the stress increase in the soil induced by the footing load. The horizontal piles located at a certain depth below the center of the footing intercepts the cone of pressure due to the footing load. Also, it is the purpose of this research to determine the effect on the soil bearing capacity for footing due to the proposed horizontal piles at the sinkhole prone area. In 1983 Baus, R.L and Wang, M.C published a research paper on soil bearing capacity for strip footing above voids. In their research, a chart for soil bearing capacity for strip footing located above a void was presented. However, in this paper we present a chart for circular footing size as a function void location and a design chart for circular footing size with a network of three underground piles. The result indicates that with the horizontal piles placed above the cavity, the stress increase caused by the footing load substantially decreases as compared to the situation of no horizontal piles, thus increases the soil bearing capacity for the normal design of footing size. The approach of using the horizontal piles placed in between the footing and the subsurface cavity is a new concept that has not been experienced previously. The results are strictly based on the analytical model of finite element program. Before full implementation for the construction practice, further research and experimental work should be conducted.
Show less - Date Issued
- 2007
- Identifier
- CFE0001643, ucf:47224
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001643
- Title
- Continuous Oscillation: Vibrational Effects and Acceptable Frequency Ranges of Small Bore Piping in Field Applications.
- Creator
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Kasprzyk, Marie, Kauffman, Jeffrey L., Bai, Yuanli, Gordon, Ali, University of Central Florida
- Abstract / Description
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In turbomachinery, a common failure mode is cracking of welds at the equipment and piping connection point. Each incidence of these cracks causes a forced shutdown to perform repairs that cost millions of dollars. This type of failure is predominately seen in small bore piping, which has a nominal diameter of 2 inches and smaller. This thesis addresses the failure prediction analysis of small bore piping, specifically in turbomachinery applications. Performing failure analysis to predict the...
Show moreIn turbomachinery, a common failure mode is cracking of welds at the equipment and piping connection point. Each incidence of these cracks causes a forced shutdown to perform repairs that cost millions of dollars. This type of failure is predominately seen in small bore piping, which has a nominal diameter of 2 inches and smaller. This thesis addresses the failure prediction analysis of small bore piping, specifically in turbomachinery applications. Performing failure analysis to predict the potential cracking of welds will allow for replacement of the piping during a planned shutdown which in the long term saves money due to costs such as expediting materials, overtime pay, and extended downtime. This analysis uses real-world applications of a chemical plant in Louisiana. The piping analyzed was connected to centrifugal compressors. The data used from these pieces of equipment included the material of construction, the piping schedule, lengths, nominal diameter, and running speeds. Based on research that shows welding the connection point with a full penetration weld greatly increases the life expectancy of the connection, this thesis uses full penetration welds in the analysis. The piping was analyzed using the software ANSYS to perform a finite element analysis, specifically examining the stress due to the induced harmonic forces. It is a common fact that having fewer supports on a vibrating pipe induces greater stresses and strains on the weld connections. Supports installed 12" from the equipment only show one to two ranges of frequencies to avoid compared to the longer piping which has four to five ranges of unacceptable frequencies. Tables are developed to relay acceptable frequencies based on observed stresses of the welds in the model.
Show less - Date Issued
- 2017
- Identifier
- CFE0006749, ucf:51862
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006749