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Frequently Asked Questions

For which types of projects has Geopier® ground improvement been used?

Geopier systems have been used to support hundreds of projects in 48 states and more than 22 countries. Geopier solutions are used to support commercial, industrial, transportation and residential applications, including buildings up to 20 stories tall, industrial tanks and buildings, heavily to lightly loaded floor slabs, MSE walls and embankments, and other transportation structures. Geopier systems are also used to provide liquefaction mitigation, uplift resistance and increased resistance to lateral loads. For more information, see our Applications section.

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Who designs Geopier® systems?

Geopier has a team of local representatives to provide you with a high level of service and support during the project design phase. These engineers work with project geotechnical and structural engineers, using loads and geotechnical information to detail the best ground improvement solution. These registered professional engineers develop the design. After preliminary design work is completed, each project undergoes an internal peer-review process by engineers at Geopier headquarters. Before going to construction, design submittals and “shop” drawings are prepared and stamped by a P.E. and provided to the general contractor.

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Who installs Geopier® systems?

Geopier licenses the rights to install our proprietary systems to select specialty contractors around the world. Licensed installers are located throughout the U.S. and Canada, Latin America and the Caribbean, Europe, the Middle East and Asia. An installer acts as design-build specialty subcontractor to the general contractor and installs the Geopier® elements per the drawings and specifications developed by the local Geopier engineer.

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How does the project team interact with the Region Engineer and installer?

The Region Engineer works closely with all members of the project team, including the geotechnical and structural engineer, architect, developer, civil engineer, general contractor and owner. Using the information provided by the geotechnical engineer, the Region Engineer develops Geopier® solutions to deliver value on your project. The specific design solution is formulated by using the structural loading conditions and drawings provided by the structural engineer or architect. Working with the licensed installer to create a seamless design-to-construction transition, the Region Engineer provides a lump sum bid for the Geopier design to the general contractor. The licensed installer then works closely with the general contractor to coordinate construction and meet project-specific schedule deadlines.

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Does Geopier provide errors and omissions insurance?

Geopier provides errors and omissions insurance upon request for projects. Our errors and omissions insurance includes a $3 million dollar per occurrence and $3 million dollar aggregate policy.

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What are Rammed Aggregate Pier® (RAP) systems?

An alternative to traditional shallow or deep foundations, Rammed Aggregate Pier systems create an Intermediate Foundation® system engineered, designed and installed exclusively by representatives of Geopier. RAP systems are constructed by densely compacting successive thin lifts of high-quality crushed rock in a 1.5- to 3-foot cavity of varying depth using patented ramming equipment. The vertical ramming action increases the lateral stress and improves the soils surrounding the cavity, which results in foundation settlement control and greater bearing pressures for design. For more information, see Rammed Aggregate Pier systems.

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How do Rammed Aggregate Pier® systems work?

The combination of the installation of the stiff aggregate pier and significant lateral stress increase in the matrix soil beneath the footing raises the allowable bearing pressure on the order of 2 to 4 times the unreinforced allowable bearing pressure and controls settlement to the project design criteria. Rammed Aggregate Pier® (RAP) elements are installed individually or in groups to support shallow foundations or floor slabs. This often eliminates the need for deep foundations and structural floor slabs. For applications where shear resistance is the controlling design factor — for example, global stability of MSE walls or embankments and stabilization of landslides — RAP systems are installed to increase the composite shear resistance. With measured friction angles of the constructed element ranging between 49 and 52 degrees, RAP elements provide significant increases in shear resistance and afford increases in the factors of safety for stability. For more information, please download or request Technical Bulletin No. 5 on RAP systems, shear resistance for global stability and slope stability.

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What types of soil conditions are appropriate for Rammed Aggregate Pier® systems?

Rammed Aggregate Pier® systems are incredibly versatile because they can be installed using either displacement or replacement methods; therefore RAP systems are effective in reinforcing good to poor soils, including very soft to stiff clay and silt, organic silt and peat, loose to dense sand, mixed soil layers, uncontrolled fill and soils below the ground water table.

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Do the Rammed Aggregate Pier® elements need to extend to a dense soil layer or rock?

Rammed Aggregate Pier® (RAP) elements do not need to extend to a firm-bearing layer like a pile foundation. The systems are designed to create an engineered crust, improving the existing soil with the inclusion of dense aggregate piers, and reinforce the soil within a zone beneath shallow footings where the stresses are the highest. In order to accomplish this, RAP elements are typically installed to depths ranging between one and two times the foundation width for settlement control.

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What are typical installation rates for Rammed Aggregate Pier® systems?

Rates depend on factors such as treatment depths, soil conditions, aggregate haul distances and site conditions. Often, installation rates range from 30 to 50 Rammed Aggregate Pier elements per day or 600 to 1,000 linear feet per day.

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How do Rammed Aggregate Pier® systems work in seismic environments?

Rammed Aggregate Pier® (RAP) systems have been used in high seismic environments worldwide to provide improved seismic bearing support, uplift and lateral resistance and reduce the potential for liquefaction. Download or request Technical Bulletin No. 1 on performance of RAP-supported footings under seismic loading conditions for more details.

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How do Rammed Aggregate Pier® systems resist lateral loads?

Rammed Aggregate Pier® systems resist lateral loads through mechanisms similar to shallow foundations, including passive resistance and sliding along the base of the foundation. For more information on design details, download or request Technical Bulletin No. 4 on lateral resistance.

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How do Rammed Aggregate Pier® systems resist uplift loads?

Rammed Aggregate Pier® (RAP) systems are used to resist uplift loads with allowable uplift design capacities that range from 25 to 75 kips. RAP elements counter uplift loads through resistance that develops along the perimeter of the RAP element as an uplift anchor located at the bottom of the RAP is pulled upward. For more information, download or request Technical Bulletin No. 3 on uplift resistance.

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