【正文】 er empirical esti mations of rock fragmentation. 2 BLASTHOLE CHARGING METHODS Drill hole charging can be carried out in different ways depending on whether the explosive used is in cartridges or in the form of loose material. The oldest charging method implies the use of a tamping rod and this system is still used to a very great extent .During the last 20years, pressed air chargers have been used and these machines provide both good capacity and also an improved level of charge concentration so that the drill holes are utilized to a higher degree. During the last few years semiautomatic chargers have been taken into use, primarily in underground work. Compressed air chargers for blasting powder in the form of loose material have also e into use on a large scale. As far as slurry blasting is concerned, special pumping methods have been developed through which charging capacity in the case of large diameter drill holes is practically good. A tamping rod must be made of wood or plastic. It must not be too thick in relation to the drill hole diameter since this can crush and damage fuse or electric detonator cables during charging work. If a good degree of packing is to be obtained during charging with a tamping rod then only one cartridge at a time should be charged and tamped. The detonator must be correctly fed into the drill hole during charging work. Compressed air chargers have been in use is Sweden for about 20 years. The first type consisted of aluminum pipes connected together and the cartridges were blown into the hole with an air pressure of 42 pounds per square inch .since that time the charging tube has been replaced by antistatic treated plastic hose of a special design. A charger includes a footoperated valve, reduction vavle with air hose, breech, connecting tube and charging hose. The semiautomatic charger permits the continuous insertion of explosive cartridge at the same rate as they are charged in the hole by the hose .Instead of a valve being used ,the cartridges pass through an air lock between two flaps. The air pressure in the charging hose is retained while cartridges are pressure in the charging hose is retained while cartridges are beins inserted .The semiautomatic charger permits considerably higher charging capacity than the normal type of charger. Explosives in the form of the form of loose material, usually ammonium nitrate explosives(ANFO), require special chargers. Two types can be differentiated: pressrure vessel machines and ejector units. Pressure vessel machines are particularly suitable for crystalline An explosives with good charging capacity. Ejector units are operate by an ejector sucking up explosive from a container through a charging hose. The explosive is then blown through the charging hose into the drill hole .There are, also bined pressure ejector machines. The charging hose used for ANFO charging operations must conduct electricity and have a resistance of at least 1K?/m and Nitro Nobel has developed a special pumping procedure which consists of a tanker vehicle which is used to pump explosive directly the drill holes. The charging capacity is very high in the case of large diameter drill holes. 3 CONTROLLED BLASTING TECHNIQUTES Controlled blasting is used to re