Geopier Rammed Aggregate Pier® (RAP) systems are efficient and very cost-effective solutions for the support of settlement sensitive structures. By avoiding massive overexcavation, as well as excess soils, these systems are considered the gold standard in ground improvement across Canada.
The Rise of the Geopier® Rammed Aggregate Pier System
The precision Rammed Aggregate Pier (RAP) System called “Geopier®” was developed by the Geopier Foundation Company early in the 1990s to provide an efficient and cost-effective foundation solution for the support of settlement sensitive structures in very difficult soil conditions. This innovative system was developed to avoid massive over-excavation and replacement in more cohesive soils. Due to its unique construction method, Geopier RAP elements provide greater capacity than traditional stone columns – particularly in non-sand soil conditions (clay, silt, organic containing and fill soils).
Ontario’s Choice for Structural Support
Of the many ground improvement techniques used throughout Ontario, none have been used on more projects than the Geopier Rammed Aggregate Pier® (RAP) system. Thousands of linear kilometers of Geopier RAP elements have been installed to support industrial, commercial, and institutional developments, mid/high-rise residentials, train/bus facilities, wind towers, storage tanks, slopes, retaining walls, transportation infrastructure as well as many other applications. The Geopier RAP system reinforces the widest variety of soil types including undocumented fill, loose sands, soft/sensitive clays, silts, and trapped organics to provide increased bearing capacity and engineered settlement control.
Geopier RAP elements are constructed with sequential lifts of aggregate Geopier RAP elements are constructed using the patented Geopier beveled tamper to deliver a high magnitude of vertical compaction energy and 15-30 tonnes of direct crown pressure during the vertical compaction of each lift. This results in a stiffer pier as well as significantly increased lateral stresses in the matrix soil. The unique Geopier direct ramming process provides unsurpassed strength and stiffness of the RAP element and matrix soil.
The Unique Advantages of Geopier RAP’s Versus Stone Columns
How can you do more with the Rammed Aggregate Pier system compared to the traditional stone column process? Here are a few of the unique features of RAP systems that outperform stone columns and other systems.
Thin lifts of aggregate are rammed to form a pier with undulating sides. Thin lifts allow for better compaction of the aggregate and results in high shear strength and stiffness. The tamper forces aggregate into the RAP element sidewalls – providing excellent pier-soil coupling.
Direct Crowd Force
Rather than being lowered off a crane, the vertical ramming energy is augmented by direct machine downward crowd pressure of 15 to 30 tonnes on each lift. Direct crowd combined with the vertical ramming energy (not horizontal) massively densifies the stone and drives up lateral stress in the enclosing soil – crowd vertical ramming results in higher performance.
The Rammed Aggregate Pier® (RAP) construction method is easily adaptable to use recycled concrete or cement treated aggregate. Alternative aggregates provide flexibility to achieve more in various soil types.
Geopier RAP elements can be installed in almost all soil conditions. The crowd vertical ramming process contributes to increasing the lateral stresses in the matrix soils, which is especially important for soils with silt or clay content that do not respond well to horizontal vibrations.
Maximum Value for Your Next Project
Performance on over 9000+ projects, as well as a myriad of independent testing and research papers provide the assurance that the RAP systems delivers the maximum value for your challenging soil projects by delivering:
The ramming process produces the superior strength of a Geopier Rammed Aggregate Pier (RAP) and develops constructed aggregate friction angles greater than 48 degrees – almost 40% greater than those reported for stone columns. Higher friction angles provide greater pier capacity, which means fewer Geopier elements versus stone columns.
Higher Bearing Pressure
Higher friction angles allow for higher bearing capacities, which results in smaller footings and lower foundation costs. Be aware that you may find your stone column or generic “aggregate pier” supplier looking to dial back bearing capacity as a result of a lower capacity pier on your next project. Insist on a Rammed Aggregate Pier for maximum bearing performance.
Better settlement control
The unique ramming process creates piers that are two to nine times stiffer than stone columns. Versatile Geopier RAPs can be used for light to heavily loaded structures. Lateral stress build-up in the enclosing soil that happens in vertically crowd-rammed RAP elements results in higher performance.
Side by side comparisons demonstrate significant performance differences between Rammed Aggregate Piers and traditional stone columns.
The orientation of installation forces is an important distinction when considering ground improvement methods in Ontario. While some geologic regions in the province are known for their deposits of sand, non-sand soil such as silt and clay are more commonly encountered in Ontario and project teams must carefully consider the performance of stone column (aggregate pier) elements in these soils. Fill is also a common occurrence – particularly in the Greater Toronto Area. No ground improvement system performs better than Geopier in undocumented fill.
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