A study of vertical bearing capacity of expansive concrete pile in coral sand foundation

To investigate the vertical bearing characteristics of expansive concrete piles embedded in coral sand foundation, the vertical static load test of single model pile was carried out in laboratory. The load-settlement curve, axial force and frictional resistance of single expansive concrete pile were analyzed, and compared with the numerical results from PLAXIS 3D software simulation. The effect of the linear expansion rates was discussed. The results show that the load-displacement curves of expansive concrete piles in coral sand show a slow change. During the loading process, the load is mainly borne by the side friction resistance of the pile. The axial force decreases with the increase of the depth, and the side friction resistance of the pile first increases with the depth and then gradually decreases, and gradually plays a role as the load increases. With the increase of expansive agent dosage, the linear expansion of pile shaft increases gradually and the pile-soil interaction becomes more obvious. Adding 25% HCSA expansive agent can increase the ultimate bearing capacity by nearly 20% and the ultimate value of pile side friction by 56%. Increasing the linear expansion rate of the pile can effectively increase the ultimate bearing capacity and side friction resistance of the pile. This study provides a reference for the pile foundation projects in calcareous sand foundation.