Vibro Replacement (Stone Columns) in Florida

In the wet top-feed process, the vibrator penetrates to the design depth using the vibrator’s weight and vibrations, as well as water jets located in the tip. The stone (crushed stone or recycled concrete) is then added at ground level to the space around the vibrator created by the jetting water. The stone falls through the space to the vibrator tip, and fills the void created as the vibrator is lifted a few inches. The vibrator is then lowered, densifying and displacing the underlying stone. This vibro replacement process is repeated in lifts until a dense stone column is constructed to the ground surface.
The dry bottom-feed process is similar, except that no water jets are used and the stone is fed to the vibrator tip through an attached feed pipe. Pre-drilling of dense strata may be required for the vibrator to penetrate to the design depth.
Vibro rigs can be fully instrumented with an on-board data acquisition system. Data from the system, such as amperage and lift rate, can then be recorded and displayed in real-time alongside specified target values on an in-cab monitor. This monitoring allows the operator to correct any deviations in real-time during the construction process to keep the vibro compaction within project specifications.

• A versatile ground-improvement method than can be adjusted to a wide variety of soil conditions and foundation requirements
• Offers an economical solution for ground improvement
• Treatment depth and spacing are established by the ground-improvement design
• Relatively quick execution so subsequent structural works can follow very quickly
• Soil improvement enables standard shallow footings which can lead to savings
• Environmentally-friendly as uses natural and in situ materials
• Noise and vibration constraints are assessed for the site and adjacent structures
• Only a small quantity soil has to be removed during the process so avoids the cost of spoil removal associated with continuous flight auger and bored piling systems

Installation records support review of the ground-improvement work. The required recording method, production parameters and acceptance criteria are agreed for the project.
A variety of production parameters are generally logged during execution including depth, current, pull down force, uplift/pull down sequence, time and date and element number.
Field trials, specified penetration tests and load tests can support verification of the treatment. The engineer defines the test program and acceptance criteria.