Medium-Scale Experimental Study of Pile Setup

Research on the gain in pile resistances over time known as pile setup is often conducted in a field using a full-scale instrumented test pile driven into soil. The challenges associated with this full-scale field method include cost, duration, subsurface heterogeneity, and impractical extraction and reuse of sensors and piles. A medium-scale laboratory program for a pile setup research was established to allow a better control of soil type and layering, reuse of sensors and piles, and subsurface characterization before and after a pile installation. A large manhole was designed to hold compacted soil for the experimental study. A steel frame was constructed around the manhole to function as a base for cone penetration tests (CPT), support for a pile driver, and reaction for a static load test. The pile driver consisted of a steel pipe that housed a 45 kg (100 lb) weight used to drive the pile. Sensors and equipment used in this study, such as Pile Driving Analyzer (PDA), strain gauges, earth pressure cells, and piezometers, were similar to those used in the full-scale field experiment. Strain gauges were placed along the pile shaft and protected by steel angles. A series of dynamic load tests and a static load test were performed on each test pile to measure pile setup. Conclusions obtained from this medium-scale test program agreed with those obtained from full-scale field experiments, making this an alternative method for future deep foundation research. New findings were obtained to better explain the pile setup phenomenon which cannot be feasibly measured in past studies.