Materiały konferencyjne SEP 1993 - tom 2

Underground Exploitation School '93 Yaluable information is stored in the database which may be used for analysis purposes and risk assesment. The objectives of the system are to assist Regional Directors and Mine Managers by highlighting problem areas where remedial action is reąuired and to offer solutions to problems such as those related to strata control accidents. Recently, the Safety in Mines Research Advisory Committee (SIMRAC) has been established in terms of the Minerals Act, 1991, under the aegis of the Department of Minerał and Energy Affairs and is chaired by the Govemment Mining Engineer (GME). The prime objectives of SIMRAC are to determine research needs based on the safety risk in mines and to advise the Director-General: Minerał and Energy Affairs on these needs. 2. Methods undertaken in South African mines to ameliorate the hazard of rockbursts There have been significant theoretical and practical advances in the understanding of mechanisms and of potential methods for the control of rockfalls and rockbursts. On the theoretical fronts these include: a) A re-evaluation of the important „energy release rate" (ERR) concept, and a revision of its often too-literally applied interpretation as a direct measure of rockburst occurence and severity of mining conditions. b) A burgeoning of data from mine seismic networks and the postulation of at least two important classes of seismic activity: events of „Crush" - type which accounts for localized face, dyke or pillar bursting, and those of „Shear" - type, which accounts for the majority of larger wide- spread-damage events, notably fault related events. c) The advancement of a simple theory to permit the design of support systems with sufficient yield ability to control the rockwall vełocities imposed by the dynamics of rockbursting. d) Increased access to, and usage of, numerical techniąues for the regional design of mining layouts. In parallel with these developments but with a more directly practical orientation, certain significant changes in strata control practice have emerged: e) In stopes, the increasing use of hydraulic props and headboards to provide active support to the fractured hangingwall in the crucial stopę face area, particularly in rockburst situations. 112 Tom II