Vibro Replacement is a technique of constructing stone columns through fill material and weak soils to improve their load bearing and settlement characteristics. Unlike clean granular soils, fine grained soils (such as clays and silts) do not densify effectively under vibrations. Hence, the necessity to form stone columns to reinforce and improve fill materials, weak cohesive and mixed soils.
Principle of Vibro Replacement
The stone columns and intervening soil form and integrated foundation support system having low compressibility and improved load bearing capacity. In cohesive soils, excess pore water pressure is readily dissipated by the stone columns and for this reason, reduced settlements occur at a faster rate than is normally the case with cohesive soils.
There are different types of installation methods which can be broadly classified in the following manner:
• Wet top feed method
• Dry bottom feed method
• Offshore bottom feed method
The installation process may be described as follows: .
1. Penetration The depth vibrator is used to penetrate the ground to be treated by a combination of vibrations, self weight, push down force (the Vibrocat method) or water jetting (wet method). Depth sensors allow the operator to know when design depth has been reached.
2. Stone feeding & Compaction Stone is feed into the holeeither from the surface via a wheel loader (topfeedmethod) or through a stone tube to the tip of the vibrator (bottom feed method).
This single charge of stone is then
compacted by the vibrator. The stone is forced downward and
outward leaving a short length of compacted stone, with a
diameter larger than the diameter of the hole created by the
vibrator.
Once this stage is completed, another charge
of stone is introduced and compacted. This process is repeated
upwards till the desired length is achieved.
Vibro Replacement is a technique of constructing stone columns through fill material and weak soils to improve their load bearing and settlement characteristics. Unlike clean granular soils, fine grained soils (such as clays and silts) do not densify effectively under vibrations. Hence, the necessity to form stone columns to reinforce and improve fill materials, weak cohesive and mixed soils.
2. Stone feeding & Compaction Stone is feed into the holeeither from the surface via a wheel loader (topfeedmethod) or through a stone tube to the tip of the vibrator (bottom feed method).