| 摘要 |
<p>The system forms a pile of hardened material such as concrete in the ground by inserting a tube (1) by hammering or vibration, and which is withdrawn on reaching the desired depth, the hole formed being simultaneously filled with concrete etc. via the tube interior. Vibrator units (19,20) are placed against the sides of the tube at the top on opposite sides and driven in synchronism, their imbalance being such that they exert equal forces at the same time parallel to the lengthwise centre line of the tube, whose mouth is thus left free.</p> |
