Ground Vibration ~ the objective of this method is to strengthen
the existing soil by rearranging and compacting coarse granular
particles to form stone columns with the ground. This is carried
out by means of a large poker vibrator which has an effective
compacting radius of 1„500 to 2„700. On large sites the vibrator is
inserted on a regular triangulated grid pattern with centres
ranging from 1„500 to 3„000. In coarse grained soils extra coarse
aggregate is tipped into the insertion positions to make up levels
as required whereas in clay and other fine particle soils the
vibrator is surged up and down enabling the water jetting action
to remove the surrounding soft material thus forming a borehole
which is backfilled with a coarse granular material compacted
in-situ by the vibrator. The backfill material is usually of 20 to
70 mm size of uniform grading within the chosen range. Ground
vibration is not a piling system but a means of strengthening
ground to increase the bearing capacity within a range of 200 to
500 kN/m^2.Soil Stabilisation and Improvement