It is extremely important to understand the mechanism of pile-soil interaction during pile installation for accurately predicting its bearing capacity. This paper presents a large-scale (1:10) model test to investigate this interaction specifically for open-ended pile penetrating sandy soil. The study focuses on pile with a diameter of 0.273 m penetrating sandy soil having a relative density of approximately 40%. Advanced monitoring techniques

including fibre Bragg grating (FBG) strain sensors and thin-film pressure sensors

were employed to meticulously analyze changes in soil plug height

strain

axial force

shaft resistance

and pile-soil interfacial stress throughout the cyclic penetration process. Following pile installation

vertical compressive static load tests were conducted with intervals of 10 and 30 days

respectively

to assess the long-term performance of the piles. Subsequently

the ICP-05 method and UWA-05 method

which are based on CPT to predict the vertical bearing capacity of piles

were compared with the bearing capacity measured by static load test. The results indicate the following: Firstly

the soil plug effect of open-ended pipe piles gradually increases during cyclic penetration

and the soil plug is partially occluded at the end of penetration. Secondly

as the depth of penetration increases

an “inverse point” of strain near the pile tip emerges. Specifically

the compressive strain at the final stage of penetration changes to a tensile strain during static stabilization

while the strain at the pile tip remains tensile at both stages. Thirdly

the radial stress of the pile body peaks at the pile tip and gradually tapers off as the h/R (h is the height from the sensor to the pile tip

R is the radius of the pile) ratio increases

indicating a significant h/R effect. Fourthly

the bearing capacity of the pile increased by approximately 12%

from 289 kN after 10 days to 323 kN after 30 days

demonstrating a notable time effect. Finally

both the ICP-05 and UWA-05 methods underestimate the shaft resistance near the pile tip

while their predictions above the pile tip align closely with measured values. Overall

the predicted pile bearing capacity using both methods is conservative

with the UWA-05 method yielding closer results to the measured values.