PURPOSE:To prepare a firm gravel pile in a short time by interposing a relay tank between a hopper for supply gravel and a casing while installing a vibrator to a support lever in the casing. CONSTITUTION:In a gravel-pile preparation device, a relay tank 10 capable of housing gravel in capacity corresponding to at least one casing 8 is interposed between a hopper 9 for supplying gravel and a fixing casing 8. A support lever 13 is inserted downward into the casing 8, and a vibrator 14 is mounted at the lower end section of the support lever 13. The support lever 13 is moved vertically by a fluid cylinder, and the inside of the relay tank 10 is supplied with compressed air from a nozzle for a compressed-air supply means 12 in the upper section of the relay tank. Accordingly, a firm gravel pile P can be formed.
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