Instrumentation for Laterally Loaded Model Piles

Abstract

Utah State University is involved with a research project funded by the Utah Department of Transportation and the Mountain Plains Consortium. The reaction of model piles subjected to lateral loading is the subject of ongoing research. The measured response of laterally loaded model pile is compared with predicted results. The model piles are 1524 mm (60 in.) long with approximately 1219.2 mm (48 in.) embedded in a soft clay soil. The piles consist of 1-in. Schedule 40, 33.40 mm (1.315 in.) OD aluminum tubes, with a wall thickness of 8.407 mm (0.331 in.). To measure the pile response to the lateral loads, each pile is instrumented with 14 pairs of foil strain gauges mounted at 91.875mm (3.75-in.) spacings. The gauge pairs were mounted on the inside wall of the seamless tube. A special installation tool was designed and fabricated at Utah State University for this purpose. A wedge-scissors device was used to mount the gauges to the inside wall. The strain gauges (CEA-13-250UW-120) are each wired into a ¼ Wheatstone bridge circuit with a dummy temperature gauge. The 28 two-wire leads along with linear variable deformation transform leads are routed through a multiplexer to a 21X data logger. The pile calibration and load test results are discussed. The measured moments compared favorably with those predicted by LPGSTAN and COM624P.