Investigation of Arching Effect Using Large Scale Model Test for Pile-Supported Embankment

摘要

A large-scale model test was carried out to investigate the archingmechanism in pile-supported embankment. 16 square model piles with400 mm width were arranged in 4 by 4 square array with a center tocenter pile spacing of 1.2 m. Soft subsoil was simulated withpolyurethane foam. Fill soil was compacted on the piles and the foamin 2.55 m height with 12 lifts of about 0.2 m thickness. The load carriedby central three piles were measured by the load cells installed on thepile heads. The loads concentrated on the piles by arching effects wereanalyzed according to fill heights. The pile efficacies that are thefractions of weight of the embankment fill carried by piles linearlyincreased up to 60% until the fill height of 1.2 m and decreased slightlyfor the greater fill heights. The pile efficacies and the stress reductionratio estimated based on the tests results were compared with thosecalculated by several arching theories. When the fill is higher than thepile spacing, the pile loads, efficacies, and stress reduction ratioscalculated by the existing theories were comparable with measuredvalues. However there found some discrepancies between the results ofthe test and the theory at lower fill height and the peak shear strength ofgranular soil cannot be taken into account in the theories.