Search Results (2)

The use of screw piles has grown rapidly, yet their varied configurations and behavior in different soils remain key research areas. This study examines the performance of Toe-wing (Tsubasa) and Spiral screw piles with similar tip areas under similar ground conditions, focusing on how the helix position (W_p) and tip embedment depth (E_d) affect the ultimate pile capacity. In the case of a fixed helix/toe-wing position with increasing pile tip depth, Spiral screw piles exhibited higher load-carrying resistance than toe-wing piles at relative densities of 55%, 80%, and 90% fine sand. Moreover, load-carrying resistance increased as the position of the helix/toe-wing increased (W_p > 0). For a fixed pile tip depth (E_d) and varying helix/toe-wing positions, spiral screw piles showed higher resistance than toe-wing piles when W_p < 90 mm. Moreover, the resistance decreased as the helix moved away (W_p/D_h > 0), and the pile tip acted independently when W_p/D_h > 1.38. Whereas, for toe-wing piles, ultimate pile capacity increased as the toe-wing moved away from the tip up to W_p/D_h = 2.15, then decreased to reflect the independent behavior of the toe-wing and pile tip. Empirical equations are presented to convert installation effort and ultimate capacity from one type to another. Full article

The installation of screw piles can cause damage to the soil, which is a dynamic and large deformation problem. In this paper, a FEM-SPH numerical model for the analysis of this large deformation problem was developed in LS-DYNA to simulate the installation process of screw piles. In addition, field installation tests of screw piles were carried out. By comparing the FEM-SPH simulation results with the experimental results and traditional FEM simulation results, it was found that the FEM-SPH coupling method has higher efficiency and accuracy in dealing with the large deformation problems caused by the installation of screw piles. Then, numerical simulations of screw piles with various parameters were conducted to analyze the differences in the installation process. The results show that the spiral pitch and pile diameter have a significant effect on the installation torque, soil stress and soil pressure during the installation process. During the installation process, the interaction between the screw pile and the soil is transferable. The installation of the screw pile will lead to the movement of soil particles in the radial and axial directions, resulting in heave damage to the shallow soil and cylindrical shear damage to the middle and deep soil. The influence range on the soil by the heave failure mechanism (HFM) and the cylindrical shear failure mechanism (CSFM) caused by the installation of screw piles is affected by pile parameters. The change in pile diameter will act on both HFM and CSFM, whereas the variation in spiral pitch will only have an influence on CSFM. Full article