Dynamic analysis model of open-ended pipe piles that considers soil plug slippage

The high-strain dynamic load test (HSDT) is a convenient and efficient method of assessing the compressive load capacity of piles. Although several numerical models are available to interpret the responses of open-ended pipe pipes (OEPPs) in the HSDT, these models cannot capture the motions of pile base soil or distinguish the difference in the external and internal soil resistance of the OEPPs. Thus, a novel fictitious-soil pile (FSP) model is developed in this study to analyze the responses of small-diameter OEPPs with soil plugs under high-strain impact loading. Apart from simulating the wave propagation in the base soil and slippage at the pile-soil interface, the proposed model also describes the sliding modes of the soil plug under dynamic load conditions (DLCs). The developed model was validated by comparing the calculated pile responses with those obtained from conventional numerical models as well as field measurements of a steel OEPP. Based on the proposed model, two sliding modes of the soil plug (bottom- and top-sliding) were found in the HSDT to be dependent on impact loading durations. The prediction of the OPEE load capacity from HSDTs could be affected by the soil sliding mode, which should be investigated in more detail in future research.