Geotechnical Engineering Circular No. 9 Design, Analysis, and Testing of Laterally Loaded Deep Foundations that Support Transportation Facilities



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12.3 INSTRUMENTATION
Instrumentation is required for lateral load tests to collect data that can be used to verify performance as well as develop design parameters (p-y curves. Instrumentation can be considered external or internal to the foundation element.
12.3.1 External instrumentation
External instrumentation for lateral load tests includes the following Linear displacement variable transducers (LDVTs) Long travel potentiometers Dial gauges

Tilt-meters Calibrated load cells Calibrated jack gauge Theodolite Such instruments are located at the head of the pile or drilled shaft to measure and record displacements
(LVDTs, dial gauges, potentiometers, theodolite, rotations (tilt-meters) and load (calibrated load cell. The hydraulic pressure on the loading jack is also measured with a calibrated gauge as a useful backup device in the event that the load cell malfunctions.


187 The external instrumentation is essentially the same as that required for an axial compression test, but there are some important differences to consider. The loads applied in a lateral load test are usually much smaller than for an axial load test, but the displacements will likely be greater. It is therefore important to select a load cell with the appropriate accuracy and precision for the range of loads to be applied. The length of travel required on the loading jack ram will need to be sufficient for the displacement anticipated. The travel on dial gauges and LVDTs will also need to be selected with the anticipated displacement magnitude in mind. In planning the load test setup, it is recommended to run a preliminary analysis for the site-specific ground conditions, foundation type and loads to gain a feel for the magnitude of displacement, such that an appropriate jack and instrumentation selection can be made. Further information on the selection and use of geotechnical instrumentation is available in Dunnicliff (1998) and Brown et al. (2010).

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