Geopier Impact® Rammed Aggregate Pier® Elements
A DISPLACEMENT TECHNIQUE
Geopier® Rammed Aggregate Pier® Systems
Geopier Impact RAPs are ground improvement elements that reinforce unsuitable soils to provide an improved subgrade for traditional shallow footing and slab-on-grade support. Impact RAPs consist of stiff columns of rammed aggregate that are constructed with a patented displacement mandrel equipped with a beveled tamping foot. The mandrel and tamping foot apply direct vertical ramming energy to densely compact successive lifts of high quality crushed rock. The vertical ramming action also increases the lateral stress and improves the surrounding soils, resulting in high-stiffness engineered elements. The displacement mandrel generates little to no excess spoils and eliminates the need for casing or dewatering. This displacement construction method is particularly advantageous on sites with caving soils, contaminated soils, and/or shallow groundwater. Impact RAPs can also be grouted to provide enhanced stiffness through relatively soft soil layers (such as organics or soft clay). For these reasons, Impact RAPs are the most-used widely used Geopier ground improvement system in the Northeastern United States.
Geopier X1® Rammed Aggregate Pier Elements
A PRE-AUGERED “DRILL AND FILL” OR DISPLACEMENT TECHNIQUE
Geopier X1 RAPs are ground improvement elements that reinforce unsuitable soils to provide improved bearing capacity and settlement control for conventional shallow footing and slab-on-grade support. X1 RAPs consist of stiff columns of rammed aggregate and are the newest type of Geopier RAP in our ground improvement “arsenal”. They are constructed with a patented mandrel and compaction chamber that allows us to install RAPs faster and more efficiently than ever before. X1 RAPs can be installed using a pre-augered “drill-and-fill” replacement construction method OR a fully displacement method that does not require pre-augering. The selected construction method is a function of the site-specific subsurface conditions. For sites with non-caving soils such as silty or clayey soils, the drill-and-fill (replacement) construction method is more appropriate and consists of predrilling an augered cavity and filling it with successive compacted lifts of imported aggregate. For sites with caving soils such as clean sand or gravel soils, the displacement method is more appropriate and allows the existing site soils to cave into the mandrel and “self-serve” as the RAP aggregate (how efficient!). Imported aggregate can be added to the displacement method to supplement the site soils as needed. Both X1 construction methods compact the lifts of aggregate with direct vertical ramming energy that results in high-stiffness engineered elements. The vertical ramming action also increases the lateral stress and improves the surrounding soils. The end result is an improved subgrade that is ready to receive traditional shallow footings designed for higher bearing pressures and a slab-on-grade.
Geopier GP3® Rammed Aggregate Pier® Elements
A PREDRILLED “DRILL AND FILL” TECHNIQUE
Geopier GP3 RAPs are ground improvement elements that reinforce unsuitable soils to provide an improved subgrade for traditional shallow footing and slab-on-grade support. GP3 RAPs consist of stiff columns of rammed aggregate and were the first type of Geopier elements to be installed in the Northeast. They are constructed using a “drill and fill” method, which consists of predrilling an augered cavity and filling it with successive lifts of high quality crushed rock. Each lift of aggregate is compacted with a patented beveled tamper that applies direct vertical ramming energy, resulting in high-stiffness engineered elements. The vertical ramming action also increases the lateral stress and improves the surrounding soils. Since GP3 RAPs are constructed with a predrilled “open-hole”, they are an effective solution for soils that are not subject to caving, such as clay. For soils that are subject to caving, Geopier Impact Rammed Aggregate Piers or Geopier GeoConcrete Columns may be more appropriate.
