Abstract:
Many underground operations consist of several tunnels acting as accesses, haulages, production levels; and airways but there is only a limited number of shafts that can be developed for any given ore body and these shafts must be sunk in the right place with the Correct configuration ta get optimum operational benefit- Despite the increasing widespread use of shafts as a primary means of access to the ore body for many mineral resources in Uganda, there is: little current and comprehensive reference material which provides a central body of knowledge spanning the various design and. cost factors involved in shaft design The purpose of-this study is to (l ) cover some aspects which. have to be considered when designing mine shafts and to. design a mine shaft, (2) to determine the geotechnical properties of the host rock and. (3) to carry out economic comparison with. the current surface mining. Laboratory tests on rock samples indicate that host rock is in category of weak rock. The dimensions of a collar, for example, its depth, cross section and thickness depend on shaft functions, character of over-burden rocks; hydrologic conditions, ground pressures and sinking method. The thickness of lining required depends upon the strength of the lining material, the- safety factor used, the- relative stiffness of the rock and support systems, the rock mass strength, the field stresses the extent of the broken zone at the time of lining installation, and the shaft diameter- It is hoped that this paper -will be used throughout industry as a quantitative basis for the comparison of various mine access options both for new and existing mines. This should form an integral part of any mine design process. Mine design is an inexact science. The inability to define the geologic environment, to determine the rock mass properties and to define the in situ stress field necessitates design under a high degree of uncertainty. No mine design is ever complete until it is tested in actual practice.
