A New Approach to Deep Foundations Bi-Directional Testing

The Top-Loaded Bi-Directional Test (“TLBT”) is a new method to apply bi-directional loads to a deep foundation element with the loading source located above the foundation head. In the TLBT reusable load assembly, loads are applied to the foundation using the R-System, which consists of two stacked steel plates located at the geotechnical resistance balance point or the foundation base connected to the load assembly via vertical elements. The top plate or the Shaft Bearing Plate (“SBP”) will transfer loads to the foundation upper portion, and the bottom plate or the Base Bearing Plate (“BBP”) will transfer loads to the foundation lower portion, as well as the foundation base. At the surface, above the foundation head, a hydraulic jack is located between a Top (“TLA”) and Bottom (“BLA”) load assembly. The TLA and BLA are connected to vertical elements which are consequently connected to the R-system. As the jack is pressurized and expanded at the surface, the R-System plates are separated and the foundation is bi-directionally loaded.

  • Upper-Foundation Portion Load-Displacement Plot
  • Lower-Foundation Portion Load-Displacement Plot
  • T-z and Q-z Plots
  • Equivalent Top-Loading Plot

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  • Applicability With active presence at industry-leading conferences, strong collaboration with technical committees, and partnership with universities, RBM identity the latest advancements and their applicability within our industry practice.
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The result of the T.E.A.M. concept has proven valid and efficient outcomes throughout each project (written reports, technical memorandums, personal communications) so that RBM team can best support all clients' requests.

ADSC The International Association of Foundation Drilling
American Society of Civil Engineers
Deep Foundations Institute
Transportation Research Board of the National Academies