ABSTRACT:

An expert system, RockRiske, has been written to assess the risk of rock bursts occurring in a given set of circumstances. The focus is on areas of a few thousand square metres and a time scale of a few months. This allows the user to take proactive measures to minimise the risk. RockRisk fulfills two roles: firstly, it allows the user to assess the risk quickly and, secondly, it serves as an educational tool for inexperienced rock engineers. Prototype versions were widely distributed within the mining industry for evaluation. The feedback was used to calibrate the weighting system and to address specific problems faced by individual mines.

RESUME:

Un system d'expertise, RockRisk, à ete ecri pour evaluer Ie risque d'explosion du rocher se produisant dans des series de circonstances. Les focus est sur les regions de quelques milles pieds carre et un lapse de temps de quelque mois. Ceci permets à I'utilisateur de prendre des mesures pro-active pour minimiser Ie risque. RockRisk rempli deux roles: Premièrement, il permets à l'utilisateur d'evaluer Ie risque très vite et Deuxiemement il sers comme un objet à eduquer les ingenieurs se specialisant dans Ie domaine du rocher qui sont encore des debutants. Des versions de ce prototype furent largement distribuer surtout a travers I'industrie minière pour l'evaluation. Le feedback fut utilise pour calibrer Ie systeme de pesenteur et Pour addresser des problemes specifics face au mines individuelles.

ZUSAMMENFASSUNG:

Ein Expertsystem, RockRisk, wurde geschrieben, das Risiko von Gebirgsschlagen Unter gewissen gegebenen Umstanden auszuwerten. Man konzentriert sich dabei auf Gebiete mit ein paar tausend Quadratmetern und auf Zeitspannen von ein paar Monaten. Diese ermöglicht dem User, fruehzeitige Maßnahmen zu nehmen, die das Risiko verringern. RockRisk erfuellt zwei Zwecke: erstens ermöglicht es dem User, das Risiko schnell einzuschatzen, und zweitens, dient das Programm als Lehrmittel fuer unerfahrene Felsmachaniker. Prototypfassungen des Programms sind weit innerhalb der Bergbauindustrie verteilt worden. Die Kommentare wurden benutzt, das Bewertungssystem zu kalibrieren, und spezifische Probleme bestimmter Minen zu analysieren.

1. INTRODUCTION

Rockbursts and rockfalls exact a heavy toll on the South African gold mining industry in terms of injuries and fatalities and in lost production. Whilst the total number of fatalities and injuries have been dropping steadily (figure 1), the rates have remained essentially constant since 1987 (figure 2). However, if one considers only rock bursts and rockfalls the situation is quite different. Figure 3 shows that the number of rock related fatalities rose to a peak of 293 in 1989 and then began a downward trend. The number of rock related injuries shows a similar trend. However, the fatality and injury rates increased by almost 50% to 1991 from which time they have remained essentially constant at the higher rate (figure 4). Recently released information suggests that the large drop in 1994 was a statistical fluctuation and the general upward trend is continuing. The increasing fatality and injury rate is commonly considered to be a result of increasing stress levels as mining progresses deeper. However, most mines have made significant staff reductions over the past few years (the number of workers employed by the gold mining industry has dropped from 456,000 in 1987 to 347,000 in 1994). Most of the staff cutbacks have occurred amongst workers employed in areas other than at the stope face. i.e. the proportion of workers employed in the most hazardous areas has, if anything, increased. So, whilst the numbers of rock related fatalities and injuries have decreased slowly, the rates have increased greatly, excepting 1994. Another factor that may influence the rock related fatality and injury rates is the fact that many of the mature mines are engaged in the extraction of highly stressed pillars and remnants. Mining of such areas elevates the risks to workers. With some mines intending to extract ore at depths of 4.5km and deeper within the next 10 years, it is clear that serious steps are required to minimize the risks implicit in mining at great depth. In essence, the safety of underground workers is paramount.

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