Sheha, Sayed Abo Elfetoh (1975) Static and dynamic finite element analysis of underground cavities with some reference to nuclear reactor containments. Masters thesis, Memorial University of Newfoundland.
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The finite element method is used to study the static and dynamic behavior of underground cavities in rock. The static loads are those resulting from the assumed free field initial stress state (in-situ state of stress) along with the deadweight of the rock. The dynamic loading is a constant step pulse resulting from a blast excitation. Temperature gradients that can follow an unexpected accident are also taken into consideration. In the range of loads applied, the rock is considered homogeneous, isotropic and linearly elastic. Cracks due to high tensile stresses are not allowed and rock sliding or joints are assumed not to exist. The effects of different types of liners such as reinforced concrete, prestressed concrete, steel plate liners, as well as active and passive rock bolting, on the stress patterns in the rock media and the liner are investigated. -- An available computer programme is modified to take into account all the variables needed for the analysis including different configuration shapes. The modified programme can deal with initial stress or initial strain states which facilitates the simulation of in-situ stress or expansions due to temperature. The initial stresses, when specified in the bar elements, allow representation of prestress in the cases of the prestressed liner and active rock bolting. As the original programme dealt with dynamic loading only, the modifications include adaptation to static loading. -- For preliminary design, the dynamic loading can be reasonably substituted by stepping up the static loading defined by the peak value by a dynamic load factor ranging between 1.15 and 1.25. However, a finite element time history analysis should be carried out for the final design. A safety factor is required to take into account thermal stresses depending on the probability of occurrence of temperature rise inside the cavity. -- Active rock bolting is found to be better than other kinds of reinforcement. Results obtained from the prestressed concrete liner are not reasonable indicating the need for further studies for modifying the tendon profile and other parameters.
|Item Type:||Thesis (Masters)|
|Additional Information:||Bibliography: leaves 105-112.|
|Department(s):||Engineering and Applied Science, Faculty of|
|Library of Congress Subject Heading:||Underground construction; Strains and stresses|
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