US Foundations : Grout Driven Pile
This method can be used for almost every type of building, and it can produce low cost piles in relation to their capacity.
Grout Driven Pile (GDP) is a method for providing a driven, cast in place, end bearing pile. This method has worldwide applications, and has become commonplace for the commercial building industry in the Pacific Northwest. Traditionally, this is accomplished by attaching an oversized, closed ended bottom shoe to a steel casing (mandrel) and driving it to bearing. The driving shoe is then released and grout is pumped through the mandrel to the bottom as it is extracted. Some installation methods pump grout through side ports in the mandrel during driving as well. After grout has been pumped to the top of the pile and the mandrel has been removed, a rebar cage and/or centralizer bar is installed back down the pile column through the fluid grout. Grout Driven Pile have traditionally been used for axial working loads in the 50-100 ton range, but working loads as high as 200 tons have been recorded.
Advantages of Grout Driven Pile
Grout Driven Pile (GDP) are a very economical method for providing medium bearing pile. Their low material costs in relation to traditional steel or precast piling provide a very low cost pile in relation to their capacity. GDP normally provide superior uplift resistance to traditional steel, precast or even to augercast pile. They will also normally achieve both end bearing and uplift design loads earlier than traditional steel, precast, or augercast pile. The removable steel mandrel works as a casing for installation below the water table. Since the soil is displaced laterally during driving, little to no spoil is generated at the top of the hole. This makes for a cleaner foundation than augercast pile, and is especially beneficial in contaminated soil conditions.
Advantages of US Foundations Grout Driven Pile System
US Foundations GDP system has several working advantages:
- Our system does not require an oversized steel shoe for the drive process. Our mandrel tip stays attached throughout the drive and extraction process, thus assuring that the outside diameter of the pile remains intact throughout the installation process. The oversize tip backreams the pile column to the required diameter during extraction.
- Our system has the advantage of using a vibratory hammer during the extraction process. This provides far superior pulling power, thus preventing the mandrel from becoming stuck during extraction due to obstructions or necking soil conditions.
- The use of a vibratory hammer during the extraction has the added benefit of re-consolidating the sidewalls of the pile column during extraction, as well as providing consolidation to the fluid grout within the column.
- Since our mandrel tip covers the full diameter of the pile column and the grout injection happens out the bottom of the tip, positive head pressure of the grout column is assured during the extraction and grouting process.
| USF Grout Driven Pile Projects | Diameter | Depth | Working Load |
|---|---|---|---|
| Springfield Shop Foundation | 16" | 20-30' | 45 tons |
| PDX Demonstration/Test Pile | 16" | 55-60' | 100 tons |