M.Ing. / As of 1991 new legislation demands that all existing and proposed mines have to submit and implement a rehabilitation plan. This plan consists of numerous phases and can cost a fair amount of money that almost none of the mines have budgeted for. During the rehabilitation process the improvement of the ground on, for example, discard dumps or slurry ponds, are not stable or adequate to enable the civil engineer to ensure stability for the new development. This can include a new sports field or low cost housing or just the peace of mind that the dump is stable and looks natural. This thesis will aim to introduce some of the numerous different ground improvement techniques that are available in South Africa and overseas.

No description available.

No description available.

Several methods have been developed to predict mining-induced ground movements. Some of these methods, such as the profile and influence functions, have been used successfully in a number of applications. Prediction methods, however, do not address the response of surface buildings and structures to mining-induced ground movements. In order to study the response of a building to ground movements, a finite element model has been developed. The program named SRMP (Subsidence Response Modelling Program) is a large displacement, small strain, two dimensional finite element program. Such model is more appropriate than the commonly used small-displacement formulations and describes more accurately this particular problem because large displacements are involved in mining-induced ground movements. Four types of elements are employed in the program, namely plane, beam, transition and friction elements. Total Lagrangian (T.L.) formulation is used for plane elements and Updated Lagrangian (U.L.) formulation for beam, transition, and friction elements. The program consists of twenty six subroutines and requires about one mega-bytes of memory. It can model the slippage between foundation and subgrade. An important feature of SRMP is that it can simulate the excavation process continuously, without re-initiating the system variables and boundary conditions. Ground movement, building displacement, and stresses can be obtained, therefore, at each excavation stage. The accuracy of the finite element model was verified through field data. The slippage between foundation and subgrade was analysed in depth. Structural deformations and stresses induced by ground movements were also studied and damage criteria in term of ground displacements were proposed. Finally, based on the SRMP analyses, appropriate measures were developed which can provide better protection to surface structures affected by excavation-induced ground movements. / Ph. D.

Appalachia requires design guidelines for the increasingly popular multi-seam longwall method. Entry layouts often depart from the ideal when finally developed. The thesis examines the occurrence of ground control problems, and possibilities for improvements in strata control, in a variety of undermining situations. The effects of upper seam loading on undermining operations are invest~gated using physical modelling. Photoelastic stress analysis is used as a powerful research tool to analyze complex multiple seam entry systems. Yield pillar use is also examined, in anticipation of their widespread application for ground control. Case examples support the research findings, and specific conclusions aim to assist layout design in interactive zones. / Master of Science

Portals are frequently an exceedingly difficult area in terms of ground control due to the near-surface, weathered, and highly discontinuous rock mass conditions. Surface and subsurface failures involving portals were analyzed using over 500 case histories which were organized into a database. Critical factors contributing to both stability and instability were isolated, and failures were classified according to location. Correlations between rock mass classes and types of portal failure were made and a four step stability analysis methodology defined. To determine critical sections of portal approach cuts for stability analysis, the Geomechanics Classification System was appended with discontinuity orientation adjustments. The most common type of failure for active portals, that of 'Crown Face Overbreak' failure, was investigated and modelled for design and support purposes. Results are confirmed using case study data. Excavation and support guidelines, based on database information the predicted failure zone from the 'Crown Face Overbreak' model are provided. / Ph. D.

No description available.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, .tohannesburg, ill fulfilment of the requirements for the degree or Mester of Science in Engineering Johannesburg, 1992 / Pillar extraction using 'handgot' methods has been practised in South African collieries fOJ' many years. During the late Sixties pillar extraction with mechanized conventional equipment commenced, and approximately a decade later, continuous miners were introduced into pillar and rib pillar extraction panels. During the years that these mining methods were practised, a vast amount of experience was gained on the various collieries. Problems were experienced by various mines and the management of these mines made numerous alterations to the mining methods with varied degrees of success, Research was 0.150 conducted by COMRO and by V,\ri01l5 mines and mining house". Apart from the recommendations of Salamon and Oravecz (1976) on pillar design in stooping sections, little information has been published and, thus, little is generally available to mine managers, planners and operators to assist them in the layout and design for plllar and rib pillar extraction. A survey of all the pillar and rib pillar practises, past and present, has been conducted for collieries in South Africa and abroad and the successes, failures, problems experienced, changes made to the mining methods and the results of these changes have been documented. The problems and successes experienced, t~ similarities and difference between mines and mining methods, and the research flndlngs have been assessed and evaluated. Design guidelines relevant to the various methods of pillar and rib pillar extraction have been established to improve the safety and performance of pillar extraction operations. These guldellnea ate not intended to be prescriptive but are designed more to bring to the attention of the mine manager, planner and operator those fllctors which should be taken into consideration during the planning and operation \)f a pillar Ot rib pillar extraction panel. In addition to the strata related factors, the economics of the mining method is important to determine if it is beneficial to do secondary ext-action, and also to assist in optimlsing the secondary extraction. The design prlnclplns were therefore appUed to diffcrtmt panel layouts, pillar sizes and extraction sequences to determine the effect on the production costs.

Mining of the Basal Reef at Jeanette Mine, is typically complicated due to an overlaying Khaki Shale (shale) that has unfavourable rock engineering properties. Shale has always been either left underground or mined as part of the orebody. The first approach can only be applied in areas where the quartzite beam (directly above the Basal Reef and below the shale) is of sufficient thickness to support the shale in the hanging wall. This method is known as undercutting. Alternatively, open stoping can be applied in areas where the shale and the Basal Reef is extracted concurrently and sent to the mill as diluted ore. Alternatively, a resue stoping method can be considered in areas where undercutting cannot be done, due to a thin quartzite middling. Resue stoping involves stowing or packing of the shale into the mined-out area and is not included as part of the hoisted rock. In the past, resue stoping was done by hand packing, which is unsuitable for a modern mine. As such, two mechanised resue stoping methods can be considered, namely; Longhole Resue Stoping and Rib Cutting Resue Stoping. Rib Cutting Resue Stoping utilises a continuous miner (“CM”) to remove the shale in a first pass, extract the reef during a second pass and backfilling the mined-out rib with shale. The use of a CM will significantly improve the extraction/mining rate, sidewall stability, backfill placement, dilution and overall safety. Longhole Resue Stoping utilises strike drives from where longholes are drilled into the shale and the reef in an up-dip direction moving on retreat. The shale is blasted with sufficient force into the mined-out area behind it, compacting it. The reef will be loaded by Load Haul Dumper (“LHD”) or dozer. It was determined that Rib Cutting Resue Stoping is more effective than Longhole Resue Stoping due to a higher extraction rate, lower dilution, reef loss reduction and improved shale sidewall stability. The operating angles and equipment height limits the application to only 51% of the available reef at Jeanette mine with favourable dip and thickness. Longhole Stoping can navigate hard rock, shale and increased dip angles; it can be applied to 91% of the available ore deposit. Longhole Resue Stoping and Rib Cutting Resue Stoping should both be considered as suitable stoping methods for Jeanette. / Thesis is submitted in partial fulfilment for the degree of Master of Science in Engineering to the Faculty of Engineering and the Built Environment, School of Mining Engineering, 2018 / XL2019

Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes disc in back pocket. Includes bibliographical references: leaf 264-272.