NON-LINEAR DESIGN OF BLAST / CONTAINMENT REINFORCED GUNITE WALLS FOR COAL MINES IN SA

摘要

Due to the high levels of methane gas produced in coal mines, the South African Department of Minerals and Energy Affairs (DME) requires the abandoned areas of a mine to be blocked off from the working parts of the mine to prevent methane exchange and/or to contain any possible coal dust explosions. Extensive testing around the world has shown that an equivalent static design pressure of 140 kPa can be used to simulate methane exchange, and 400 kPa for explosion pressures. The large number of walls to be constructed underground requires a cheap, simple and easily constructable design. Rather than using conventional elastic designs of reinforced gunite walls, non-linear yield line analysis techniques and the inclusion of the beneficial effects of membrane action has resulted in a wall with a thickness of only 1/3 of the wall thickness for conventional designs for the same loads. Due to the wide range of dimensions that can possibly occur for each possible underground wall position, design curves for standard wall designs have been produced to facilitate quick and easy construction. Full-scale tests performed underground support the design philosophy and construction method.