Flexible, Cost-effective Jet-Grouted Deep Pile Foundation Alternative

Technology #12865

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Categories
Researchers
Michael McVay
Peter Lai
David Bloomquist
Managed By
Richard Croley
Assistant Director 352-392-8929
Patent Protection
US Patent 8,596,922

Invention

The University of Florida is seeking companies interested in commercializing a new approach to jet-grouted deep pile foundation installation. Most, if not all heavily loaded structures or buildings on poor soil conditions are supported with deep foundations in order to distribute loads deeper into the ground, mitigating settlements. Generally, deep foundations fall into two categories: (1) a driven pile: a prefabricated member that is driven or vibrated into the ground; and (2) a case-in-place shaft: a hole constructed in the ground and subsequently filled with engineered materials. Both types of deep foundations have advantages and disadvantages. This jet-grouted deep pile foundation combines the advantages of both driven and cast shafts while minimizing or eliminating the disadvantages of each, providing a flexible and cost-effective alternative.

Application

A jet-grouted pile that can be utilized in deep foundations on both large-scale and small-scale projects

Advantages

  • Provides scalable technology, facilitating use in both small and large scale foundation projects
  • Automatically performs capacity assessment at the end of installation, eliminating the need for costly load testing equipment, instrumentation and time delays
  • Designers know the axial and lateral capacity of the pile at the design stage, providing significant economic savings over both driven piles and cast-in-place shafts
  • Allows for use of a multitude of material types and shapes in order to fit specific applications and load values
  • Low startup cost and easy to use, providing a competitive advantage

Technology

There are several major components of the jet-grouted deep pile foundation: (1) the structural member, including an associated grout membrane; (2) the jetting pipes and nozzles; (3) the grout delivery and return system; (4) the grout mix design; and (5) the jetting and grouting process. The structural member is capable of carrying the axial, lateral, and torsional loads from the structure. Attached to the outside of the structural member is a grout membrane to limit the outward expansion of the grout bulb and prevent soil contamination. The grout delivery system travels from the ground surface to the grout membranes throughout the pile and back to the surface. To accurately assess the grout pressure, UF developed a grout stress gauge which uses an air bladder controlled value, glycerol/water fluid and a pressure gauge. The grout mix has increased flowability and binding characteristics, over typical compaction grout, which will ensure good return pressures in small grout pipes.