Volume 21, Issue 3 (September 1998)
Laboratory Modeling of Inclined-Loaded Shafts in Sand
Baseline information is presented for preparing and conducting load tests on larger laboratory-scale models of shafts in sand under static and cyclic inclined loading. The shaft models were prefabricated and reusable, with a 52-mm-diameter and depth-to-diameter ratios of 3, 6, and 9. The procedures used for soil deposit preparation in a unique combined sand hopper and testing chamber are presented, along with the testing approaches for static and cyclic loading. Testing was done in uniform deposits of loose and medium dense normally consolidated sand and dense overconsolidated sand. Loads were applied to the shafts at seven load inclinations using a hydraulic actuator system controlled by a mini-computer. For the static tests, loads were applied at a constant displacement rate; for the cyclic tests, loading was force-controlled, and it was applied as a one-way sinusoidal waveform. Measurements of load, displacement, and rotation were taken automatically with transducers linked to a data acquisition system, and important issues in data interpretation are discussed. Typical test results show that: (a) cyclic loading results in slightly stiffer and stronger response than static loading for comparable initial soil conditions, and (b) the accumulated cyclic displacements can be quantified in a straightforward manner.