Gravity Flow Under Moisture Conditions – Control and Management of Drawpoint Mudfl ow

摘要

After many years of studying the rock mass gravitational fl ow phenomenon, it is well known that moisture conditions may change the mechanical properties of the caved and broken material, causing different problems at drawpoints. One specifi c problem, perhaps one of the most unpredictable and uncontrollable, is that of mudfl ows (also known as mud rushes). The aim of this paper is to show how to establish optimal extraction rates at a drawpoint in order to avoid the closure of that drawpoint due to the high risk associated with having high-technology automated loaders working in the production level of panel cave and block cave mines prone to mud fl ow events. This optimisation should take into consideration critical restrictions related to mine planning, such as the need to reach the planned production. It is also important to consider the correct design of surface (in the subsidence zone) and underground drainage systems to prevent groundwater or rainwater entering muck piles, fi lled stopes, galleries or open cuts. With these considerations, and keeping in mind other factors that should be included in a sensitivity analysis of variables, it is possible to fi nd a correlation between the percentage of extraction from a drawpoint and the possibility of occurrence of a mudfl ow. Finally, this paper proposes different draw strategy techniques in order to mitigate potential mudfl ow issues on a caving production level.