Plugging mechanism of soil column within pipe pile using uncrushable uniform particle assembly

This studyfocuses on the bearing capacity of a soil plug through fundamental research examining on the bearing mechanism of uncrushable soil particles both experimentally and numerically. Experimentally, push-up load tests of uncrushable soil particles having various aspect ratios within an open-endedsteel pipe pile were carried out. Alumina balls4 mm in diameter were employed to model the uncrushable soil particles. Numerically, Discrete Element Method (DEM)was used to simulate the experiments. First, the element tests of the alumina balls and its DEM analyses were carried out to characterise the properties of the alumina balls and to determine appropriate analysis parameters used in the DEM simulations of the push-up load tests. Then, the push-up load tests of soil plugs make of uncrushable particles and its DEM analyses were carried out.Both the experimental and numerical results clearly showed that the soil plug capacity is dominated by the aspect ratio, and that hardening and softening behaviours of the push-up force occurs in all cases. Finally, the experimental results in this study were compared with the push-up load tests of crushable soil plug obtained in the previous study. Possible influence of crushability of soil particles on the plugging behaviour during push-up loading was discussed based on the comparison.