Behavior and Soil-Structure Interaction of Pervious Concrete Ground-Improvement Piles under Lateral Loading

Granular column ground-improvement methods are widely used to improve hearing capacity and provide a drainage path. However, the behavior of granular columns depends on the confinement provided by the surrounding soil, which limits their use in poor soils. A new ground-improvement method is proposed using pervious concrete piles to provide high permeability while also providing higher stiffness and strength, which are independent of surrounding soil confinement. Building on prior research on the behavior of vertically loaded pervious concrete piles and granular columns, this paper investigates the behavior of laterally-loaded pervious concrete piles and the effects of installation on their response. Two fully-instrumented lateral load tests were conducted on a precast and cast-in-place pile using different installation methods. Advanced sensors measured the soil structure interaction during installation and under lateral loading. Test results confirmed that laterally-loaded pervious concrete ground-improvement piles behave as flexible laterally-loaded piles, while still providing permeability similar to granular columns. Although the ultimate load capacity of the two piles was not affected by installation, the cast-in place pile had 55% of the displacement of the precast pile at ultimate load, which indicates soil densitication and lateral compression due to installation. The directly-measured p-y curves for the cast-in-place pile also better matched the existing procedures developed for driven piles and showed a higher stiffness and ultimate soil reaction than the precast pile. Results also determined that the zone of soil affected by installation extended to 2.5 D from the pile surface. (C) 2015 American Society of Civil Engineers.