Bearing capacity analysis of open-ended piles considering the degree of soil plugging

This paper presents a new design approach for predicting the degree of soil plugging and the inner skin friction of axial-loaded open-ended piles. The main objective of this study was to propose the SPT-based design method considering the plugging effect, since the SPT test is commonly used to identify the subsoil condition in sandy soils. The plugging effect for open-ended piles was quantified using field plugging measurements and the results of three full-scale field pile load tests. Based on the plugging measurements, the relationship of the plug length ratio (PLR) with the soil properties, pile geometry and pile driving condition was established. Additionally, a linear relationship between the PLR and incremental filling ratio (IFR) was proposed. Full-scale tests were performed on three instrumented piles with different diameters (508.0, 711.2 and 914.4 mm). An instrumented double-walled pile system was used to measure the outer and inner skin friction along the pile shaft. Based on the results of the full-scale field pile load tests, the inner skin friction of the open-ended piles was proposed as a function of the IFR and pile diameter. The predicted values were consistent with the measured values, such as the IFR and inner skin friction. The proposed method can predict the degree of soil plugging and the inner skin friction of open-ended piles and be selected as convenient option in engineering field.