Thesis (M. Sc.)--University of Hong Kong, 2003. / Also available in print.

Thesis (M. Sc.)--University of Hong Kong, 2003.

No description available.

published_or_final_version / Applied Geosciences / Master / Master of Science

Thesis (M.Sc.(Earth Science Management and Practice))--University of Pretoria, 2007. / Abstract in English. Includes bibliographical references (leaves 95-99).

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Includes bibliographical references (leaves 401-406). Available also in a digital version from Dissertation Abstracts.

This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young's modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. Push-out tests are used to determine the bond strength by applying an axial load to the cement plugs. A total of 130 push-out tests are performed as a function of borehole size, plug length, temperature, and degree of saturation of the tuff cylinder. The use of four different borehole radii enables evaluation of size effects. A well-defined exponential strength decrease with increasing plug diameter results.