Search

To explore the supporting performance of oblique piles (OPs) used in pit excavation, a field test was performed at a foundation excavation using OPs with various inclination angles. Then, numerical models using the finite-element method were established and validated on the basis of the field test result. A novel arrangement of oblique‒vertical alternating piles (OVAPs) was proposed as the retaining structure for excavation. The displacements of the pile top, internal forces of the pile body, earth pressures on the pile body, and soil deformation were observed and studied. The results indicated that both pile inclinations and arrangements had an effect on the supporting performance of oblique piles. Furthermore, four effects were summarized to explain the advantages and working mechanisms of OP and OVAP arrangements used in retaining structures. Finally, a force analysis of oblique supporting piles in the foundation pit was conducted and a simplified formula was derived and applied to calculate the bending moments of pile bodies under different working conditions. [ABSTRACT FROM AUTHOR]

Prestressed high-strength concrete (PHC) piles have been widely applied as foundations. However, the application of PHC piles was challenging under earthquake hazards. With the increasing demand for PHC piles in earthquake-prone areas, PHC piles reinforced with non-prestressed tendons (PRC piles) were proposed to address the problems. A full-scale field test for one PHC pile and four PRC piles with different non-prestressed tendon ratios (NPTRs) was conducted under horizontal cyclic loading, and their seismic performances were evaluated in terms of hysteretic behaviours, horizontal bearing capacity, ductility, pile deformation, and crack patterns. The results indicated that adding non-prestressed tendons led to an improvement in the hysteresis characteristics and deformation capacity but a decrease in the horizontal bearing capacity. The displacement ductility coefficients of all specimens reached or exceeded 2.8, and there was an optimal NPTR of 0.75% that maximized the ductility of PRC piles, which was 62.5% greater than that of the PHC pile. The pile-soil interaction was considered by analyzing the crack development of the surrounding soil and piles. • A Full-scale test of PHC piles reinforced with non-prestressing tendons were conducted under cyclic loading. • Adding non-prestressing tendons can enhance the ductility of PHC piles. • There was an optimal ratio of non-prestressed reinforcements assisting PHC piles behaving best in seismic performance. • Pile-soil interaction was considered by investigating pile cracking and soil cracking. [ABSTRACT FROM AUTHOR]