18 Ground improvement by deep vibratory methods
a stone column consisting of well-compacted coarse material was formed.
The in-situ soil was displaced laterally providing, at the same time, a supporting horizontal confining pressure.
To build efficiently such a vibro replacement stone column, as the system
was soon called, the available depth vibrator proved rather unsuitable. Not
only was its surface not smooth enough, and the water pipes attached to it
prevented rapid penetration, but the vibrator and its extension tubes were
not connected with each other rigidly enough to exercise the desired downward thrust.
2.3 THE TORPEDO VIBRATOR AND THE VIBRO
REPLACEMENT STONE COLUMN METHOD
The new findings gathered on-sites formed the basis of considerations to redesign the original vibrator which was used unaltered for more than 20 years
in sand compaction and to make it suitable for the treatment of cohesive
soils. Finally, the Keller Company developed a much improved depth vibrator
which was, as a result of its shape, called Torpedo vibrator (Figure 2.10). It
was characterized by a much more powerful 35 kW electric motor, running
Figure 2.10 The Keller Torpedo vibrator. (Courtesy of Keller Group plc, London, UK.)
a stone column consisting of well-compacted coarse material was formed.
The in-situ soil was displaced laterally providing, at the same time, a supporting horizontal confining pressure.
To build efficiently such a vibro replacement stone column, as the system
was soon called, the available depth vibrator proved rather unsuitable. Not
only was its surface not smooth enough, and the water pipes attached to it
prevented rapid penetration, but the vibrator and its extension tubes were
not connected with each other rigidly enough to exercise the desired downward thrust.
2.3 THE TORPEDO VIBRATOR AND THE VIBRO
REPLACEMENT STONE COLUMN METHOD
The new findings gathered on-sites formed the basis of considerations to redesign the original vibrator which was used unaltered for more than 20 years
in sand compaction and to make it suitable for the treatment of cohesive
soils. Finally, the Keller Company developed a much improved depth vibrator
which was, as a result of its shape, called Torpedo vibrator (Figure 2.10). It
was characterized by a much more powerful 35 kW electric motor, running
Figure 2.10 The Keller Torpedo vibrator. (Courtesy of Keller Group plc, London, UK.)