Plugging Response of Open-Ended Pipe Piles in Layered Sandy Soils

This paper explores the plugging response of open-ended pipe piles (OEPs) during installation in layered sandy soils, using both calibration chamber tests and field test data. Eight calibration chamber experiments were performed in layered and uniform silica sand samples. From these tests, sensing and development distances were measured, and the incremental filling ratio (IFR) was calculated from the digital images collected during pile installation to quantify the degree of plugging. In addition to sensor-based results, displacement fields in the soil domain were obtained using digital image correlation. The results show that the sensing distance for OEPs is similar to the sensing distance for closed-ended pipe piles (CEPs) in both loose-over-dense and dense-over-loose sand sample configurations. However, the development distance is different for OEPs and CEPs because of plugging. The plugging response of OEPs changes as they transition between layers. The IFR increases when an OEP transitions from a loose to a dense sand layer and decreases when an OEP transitions from a dense to a loose sand layer. This premise was used to develop a differential equation to estimate the IFR of field piles using cone penetration test data. The proposed equation for the IFR was calibrated using three field tests and validated using three additional field tests. For these three validation tests, the average absolute mean error was 5.6% and the average root mean square error was 16.4%.