4. Title aod Subtitle A MODEL FOR THE DETERMINATION OF FLYROCK RANGE AS A FUNCTION OF SHOT CONDITIONS

lb. Abstract. h f f h · · · d d ' Flyrock 1s t e source o most o t e 1n]ur1es an property amage 1n a majority of blasting accidents in surface mines. A quantitative correlation between shot conditions and maximum flyrock range can be used to define a "blasting area " in which no personnel or equipment should be,present during a shot. The approach used was to develop a model that correlates shot conditions and initial flyrock velocities and permits computation of flyrock range from ballistic trajectories. The Gurney formula for velocity of explosively-propelled plates or fragments was adapted to explosively-propelled flyrock from vert i cal rock faces or from bench tops. The modified Gurney formula was then "calibrated" with measured flyrock velocities from mining and explosives literature. Charts \Jere then developed for possible field use which give maximum flyrock range as a function of shot conditions. The model indicates that for flyrock from vertical faces, borehole diameter, roQn1mum burden and height of explosive column define maximum flyroc