INTRODUCTION
The vibro replacement technique developed by Keller in 1950's. At the heart of the system is the depth vibrator which is suspended from extension tubes. The total length of the vibrator and extension tubes assembly being equal to or greater than the treatment depth. Air/water jetting system are attached to the sides of the vibrator. The vibrator and extension tubes are suspended from a crane or a similar base machine. A stone delivery system is used to supply the stone to the compaction point. The concept is to improve load bearing capacity of the soils.
Figure 1: Typical operation setup
Figure 2: Vibro Replacement vibrators are well armed around their tip and body. Fin prevent spinning. High pressure water jet are place at the tip of the vibrator.
INSTALLATION PROCESS
To construct stone columns, the vibrator is allowed to penetrate to the designed depth and the resulting cavity is filled with hard inert stone (grading 40-75mm), free of clay and silt. To develop the required interaction between stone columns and surrounding soils, it is necessary for the stonefill to be introduced and compacted in stages, each charge of stone being thoroughly compacted.
PENETRATION
Figure 3: Assisted by jetting water, the oscillating vibrator penetrates to the designed depth under it's own weight. Thereafter the water jets are adjusted in such a way that an annular space remains open around the vibrator and it's extension tubes.
REPLACEMENT
Figure 4: Once at depth course grained backfill material is now fill into the hole down to the toe of the vibrator. By moving the vibrator in small steps up and down and by horizontal forces of the machine itself, the supplied stones are pressed into the existing soil.
FINISHING
Figure 5: With stones being added as required this process is repeated up to ground level, leaving on completion a well compacted, tightly interlocked stone column surrounded by soil of enhanced density.
p/s : Credit to Ariffin
No comments:
Post a Comment