GP3® System

The patented Geopier GP3® system uses replacement Rammed Aggregate Pier® (RAP)

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GP3® System

The patented Geopier GP3® system uses replacement Rammed Aggregate Pier® (RAP) elements to reinforce good to poor soils, including soft to stiff clay and silt, loose to dense sand, organic silt and peat, and variable, uncontrolled fill.

The GP3® system allows for visible inspection of the spoils, and the opportunity to address changing ground conditions as they happen.

GP3® is an effective method for massive over-excavation and replacement or deep foundations, including; driven piles, drilled shafts or auger cast-in-place piles.

Advantages of the GP3® System

Strong and Stiff

Vertical impact ramming results in high density and high strength RAP elements providing excellent support capacity, increased bearing pressure up to 500 kpa and excellent settlement control.


Thousands of structures are currently supported. Proven experience ensures high levels of performance and reliability.


Often results in 20% to 50% savings compared to traditional deep foundations.


Rapid installation process means shorter construction schedules.


Excellent on-site quality control is maintained through visual spoil observation, full-scale modulus load tests and inspecting and testing the system.

The Construction Process

The unique installation process utilises pre-augering and vertical impact ramming energy to construct RAP elements, which exhibit unsurpassed strength and stiffness. RAP solutions are designed to provide total and differential settlement control and increased bearing support to meet project requirements.

1.      The process first involves drilling a cavity. Drill depths normally range from about 1m to 8m, depending on design requirements. Pre-drilling allows you to see the soil between the borings, ensuring that the piers are engineered to reinforce the right soils.

2.     Layers of aggregate are then introduced into the drilled cavity in lifts (approximately 200-300mm) A patented bevelled tamper rams each layer of aggregate using vertical impact ramming energy, resulting in excellent strength and stiffness. The ramming action densifies the aggregate vertically and forces it laterally into cavity sidewalls. This results in excellent coupling with surrounding soils and reliable settlement control.

3.     Following installation, RAP elements support shallow foundations, floor slabs and tank pads and reinforce slopes and embankments. The footing stresses are attracted to the stiff RAP elements, resulting in engineered settlement control.