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Vibro-replacement is used to improve cohesive soil types. Thereby, coarse extraneous material is filled into the vibrating hopper and a load-bearing gravel or crushed stone column is produced. If the crushed stone columns are arranged in a grid the building ground can be improved area-wide.
1. Positioning of the bottom-feed vibrator guided on the leader
2. Material bucked fills feeder pipe with intended material
3. Vibrator is put into operation and penetrates the ground down to the projected depth using rope crowd force and supported by compressed air. Soil is placed to the side.
4. Vibrator is pulled up a little, installation material is filled with compressed air, then pressed again while continuing to vibrate (“stuffed”).
5. Finished vibro-replacement column with better interlocking
Filling with extraneous material with subsequent stuffing creates a load-bearing gravel column with a greater strength than the untreated ground.
The so-called bottom feed vibrator which penetrates a fine grained, non-compactable soil is fitted with a device for addition of material.
Vibration is carried out under addition of compressed air emerging at the vibrator tip and supporting the vacated space.
After the final depth has been reached the vibrator is systematically hoisted. Gravel or crushed stone are filled in through the material feeder and emerge at the vibrator tip under addition of compressed air.
Repeated lowering of the vibrator compacts the added material. Moreover, it is densely pressed and/or stuffed into the adjacent soil.
Alternating hoisting and lowering of the vibrator combined with batch filling with material produces a so-called vibro-replacement column.
Smaller groups of columns result in a selected soil improvement. An area-wide improvement with extensive column grids is applied, for example, under dams or foundation plates.
The video shows an LB 24 rotary drilling rig in operation with a deep vibrator mounted on the leader.