A simplified non-axisymmetric pile-soil interaction model for pile integrity testing analysis

Abstract

A simplified model of non-axisymmetric pile-soil interaction (NPSI) that considers both vertical and radial motions of the pile body is developed and applied to the investigation of pile integrity test (PIT) with eccentric hammer impact. The pile is treated as a simplified three-dimensional (3D) continuum and the soil along the pile shaft is simulated as a series of independent thin soil layers, while the soil under the pile base is defined by the fictitious soil-pile model. Theoretical solution of the velocity-time history of each point on the pile top section is deduced by integral transformation technique. Based on the NPSI model, characteristics of test signals of PIT for large-diameter piles under non-axisymmetric condition are analyzed. The optimal testing position for acquiring signals, which minimizes the influence of high frequency (HF) interference resulting from the pile body 3D effect, is identified. Findings from this study provide the basis for accurate interpretation of the PIT of large-diameter piles with eccentric hammer impact.