The Geotechnical Laboratory is used to study the material properties of soil and the interactions between soil and structural elements such as steel, concrete, geosynthetics, or timber that are used for bridge foundations and retaining wall systems.
The Geotechnical Laboratory consists of a standard indoor testing facility and several unique outdoor testing facilities. New materials and methods of design and construction are tested and evaluated in both indoor and outdoor environments to determine their acceptability and to identify opportunities for improvement.
The indoor facility is capable of conducting basic index tests for characterizing soil and aggregate materials for both research studies and production projects. Unique capabilities include a 12-inch direct shear device, a 6-inch diameter triaxial unit, and a 20-kip universal testing machine. The laboratory also has a variety of fixtures and auxiliary equipment to conduct a variety of specialized tests to include the evaluation of innovative instrumentation for geotechnical applications.
Figure 1. Large-Scale Shear Test Device.
Figure 2. Large Diameter Triaxial Device.
Figure 3. Strength Testing of Geosynthetics.
Figure 4. Evaluation of Pressure-Sensing Technology.
Figure 5. Connection Testing of Geosynthetics.
Figure 6. Calibration Reaction Assembly.
In addition to the use of the Geotechnical Laboratory, the Structures Laboratory has also been used by the geotechnical research team for performance testing of large-model geosynthetic reinforced soil.
Figure 7. Performance Test for Geosynthetic Reinforced Soil Composite.
One of the outdoor laboratory facilities consists of two test pits that are 18 feet wide, 23 feet long, and 18 feet deep. The pits can be filled with various soil types for modeled shallow or deep foundation experiments, and have also been used to conduct full-scale wall experiments and to test the tension capacity of ground anchors. The pits have reinforced concrete walls, sump pumps to control water-table levels, and anchorage systems to provide reaction loads for experiments.
Figure 8. Outdoor Test Pit Facility (Mechanically Stabilized Earth (MSE) Shoring Wall Experiment).
Figure 9. Outdoor Test Pit Facility (Helical Anchor Tensile Tests).
The pits have a separate building for the storage of the load-test equipment and a control room for the data-acquisition systems. The laboratory includes two additional outdoor test sites where full-scale bridge piers, abutments, and retaining wall structures were constructed for research and testing purposes. The following are a few examples of full-scale experiments in these locations to illustrate the capabilities of Turner-Fairbank Highway Research Center (TFHRC) to lead the advancement of the state-of-the-art.
Figure 10. Geosynthetic Reinforced Soil (GRS) Test Pier at TFHRC
Figure 11. Prototype Geosynthetic Reinforced Soil-Integrated Bridge Systems (GRS-IBS) at TFHRC
Figure 12. Long- Term Dead Experiment Adjacent to the Outdoor Test Pit Facility
The facility has an outdoor strong floor that is also available for the construction and testing of full-scale geotechnical features on a rigid concrete platform. The spacing of the anchorage locations is 3 feet by 3 feet, each with a 300 kip capacity—similar to the Structures Laboratory—for the capability of a variety of load fixtures and arrangements.
Figure 13. Outdoor Strong Floor
Figure 14. National Cooperative Highway Research Program (NCHRP) 12-59 Experiment on the Outdoor Strong Floor
|»||Office of Infrastructure R&D|
|»||Infrastructure R&D Program|
|»||Infrastructure R&D Experts|
|»||Infrastructure R&D Laboratories|
|»||Infrastructure R&D Projects|
|»||Infrastructure R&D Publications|
|»||Infrastructure R&D Topics|
Turner-Fairbank Highway Research Center
6300 Georgetown Pike
McLean, VA 22101-2296
|»||2011 FHWA Infrastructure Research and Technology Strategic Plan Goals and Objectives|
|»||Federal Highway Administration Office of Infrastructure|
|»||Pavement and Materials Discipline|
|»||Bridges and Structures Discipline|