QUANTIFYING THE PROBABILITY OF DETONATOR TIMING OVERLAP IN SURFACE MINE BLASTING BY THE APPLICATION OF MONTE-CARLO SIMULATIONS TO INITIATION PLANS

摘要

The control of vibration from surface mine blasting by the application of detonator (cap) delay techniques has been universally accepted for many years. For almost as long it has been known that, for delay techniques to be effective, a minimum of 8 milliseconds delay must exist between blast holes. Over the last 20 years non-electric detonator systems based on shock-tube techniques have become widely used in the explosives industry. These systems consist of a series of surface delay detonators connected to additional in-hole delay detonators. Each detonator includes a pyrotechnic delay and as such is subject to timing scatter. This paper examines the application of Monte-Carlo simulation techniques to determine the probability of timing overlap and thus high vibration. Monte-Carlo simulations are performed on a range of surface blast initiation plans employing the non-electric shock-tube initiation system. The 8-millisecond overlap rule is used to give a measure of quality for the various design options. Suggestions are made on strategies for the design of surface initiation patterns to minimise delay overlap and therefore vibration. Additional work is described, based on a case study, where linear superposition and Monte-Carlo techniques are combined to examine the possibility of choosing delay patterns to minimise vibration levels without reference to overlap.