The use of reinforcing bar (rebar) anchored with resin is a common method of rock support in both hard and soft rock mining. The average bond strength, or the load that the support can sustain for a linear length of bond to the rock, is typically determined through a series of pull tests. The average value of bond strength varies widely, since it is dependent on in-situ rock properties and environment. It is an important value because it allows mine engineers to select the appropriate length and pattern spacing of installation for the support. When a stiff support, like resin-anchored rebar, is placed in a weak, soft material, such as potash, the average bond strength tends to be lower in magnitude than for a typical hard rock installation. This research was primarily aimed at determining the failure mechanism, in soft rock applications, by which the support loses adhesion and begins to fail by sliding. Results of field pull testing determined that the resin-rock bond strength was the limiting factor controlling when adhesion loss occurred. This study investigated how the bond strength may vary given a number of variables typically found in a potash mine environment. Results reported from testing did not indicate variation in the bond strength of resin anchored rebar, significant for mining applications, given changes in resin cure time, vicinity to active mining areas, or the rock type to which the resin was adjacent. Using the results of laboratory and field testing, an equation was developed to estimate load on in-situ resin anchored rebar given deformation measurements taken from the field. This equation will help determine safe limits for fracture separations opening in the backs of potash drifts. Investigating the behaviour of resin anchored rebar in potash may lead to methods to improve bond strength and calculation of factors of safety for patterned ground support.

No description available.

Dissertation submitted in partial compliance with the requirements for Masters Degree in Technology: Electrical Engineering (Light Current), Technikon Natal, 2001. / M

No description available.

Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Engineering, 1996 / One of the major impediments in the field of numerical modelling in rock mechanics is limited knowledge of the mechanisms of fracture and failure of brittle rock. One important tool for improving the understanding of rock behaviour is the use of laboratory experiments under controlled conditions. The Displacement Discontinuity Method, capable of fracture growth simulation (DIGS), has been used to model fracturing in samples under punch loading. A Finite Difference Method, capable of plastic deformations due to its explicit time marching scheme (FLAC), has also been used to model the punch tests. By comparing numerical simulations with results from laboratory experiments of punch tests, it has been possible to define the basic failure mechanism for pillar foundation failure. Two different test set-ups were used namely, steel jacketed axisymmetric punch tests and long strip punch tests in the triaxial cell which is built for these specific tests. The layered structure of the test specimens and in the test procedure had significant effects on the fracture pattern as well as the failure load. When the layer is near to the punch area, then both the layer and the layer conditions had a strong effect on the failure load. When the layer was frictionless, the failure stress dropped by about 20 percent. The same result occurred in both the axisymmetry and strip loading tests. When shear fractures intersect a layer with either low or high friction it terminates. This is not the case for the tensile fractures, which can pass through the layer media. However, it is important to note that the tensile fractures which originate from near the cone area can not pass through the layers. They stop at the interface.

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in prined format.

Thesis (Ph. D.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 170-180).

Thesis (M.S.) in Mechanical Engineering--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 59-62).

Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

published_or_final_version / Applied Geosciences / Master / Master of Science