Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities
Coordination with Axial Load Tests
Download 6.03 Mb. View original pdf
|
Soldier Rev B
- Navigate this page:
- 12.2 LATERAL LOAD TEST METHODS
| 12.1.7 Coordination with Axial Load Tests Lateral load tests can be performed on a test element used for axial load testing following completion of the axial load test. The lateral load test should not be performed before the axial load test as it may change the stress conditions and soil contact around the foundation element, which may impact the axial resistance (the lateral load test may require relatively high deflections in order to investigate the Strength Limit State. Axial load tests are discussed further in Hannigan et al. (2016), Brown, et al. (2010), Brown et al. (2007), and Sabatini et al. (2005) for driven piles, drilled shafts, CFA piles, and micropiles, respectively. 12.2 LATERAL LOAD TEST METHODS Static lateral load tests are the most common form of lateral load test applied in practice. Other types of tests include the Rapid Load Test, also known as a Force Pulse lateral load test, and bidirectional load cell tests. 12.2.1 Static Lateral Load Tests ASTM D describes The Standard Method of Testing Deep Foundations Under Lateral Load. Several alternative systems for applying the lateral load to the deep foundation element and measurement movements are provided in this standard. Requirements for presenting the results of lateral load tests are also provided in this standard. A conventional static lateral load test involves applying a load against a pile or drilled shaft, using a jack and reaction system. The load application can be by pushing or pulling, depending on the test setup. Figure 12-1 below illustrates atypical setup with a hydraulic jack and load cell bearing against the head of a drilled shaft. A curved concrete saddle is cast between the load cell and the surface of the shaft, in order to distribute the load evenly into the shaft and minimize rotation and torsion as the load is applied. This bearing surface may also be a hemispherical steel plate. Sometimes the head of the pile or shaft is made-up with a square or rectangular reinforced concrete pad or pedestal, against which the jack and load cell are placed. A quick setting high strength grout maybe required between the foundation element and the bearing plate, to minimize stress concentrations. An example of a one-way lateral load test setup is shown in Figure 12-2. The hydraulic jack is bearing against steel channels and high tensile steel bars transfer the load into the reaction system (not shown. A load cell is located between the jack ram and the steel plate. Dial gauges are shown near the head of the casing, bearing against a reference beam. Cables from strain gauges are seen at the pile head, and the yellow pipe is an inclinometer casing for measuring deformations during the test. |