Experimental and numerical investigations on the mechanical response of full-scale PHC pile foundations for solar power generation

The PHC (pre-stressed high-strength concrete) pile foundation, serving as an innovative supporting structure for solar power stations, is subjected to complex loading conditions in engineering scenarios. In this study, field tests of the full-scale PHC Pile foundation were conducted in sand layer, loess layer, and double-layer sites to investigate its operational behavior under different load conditions. The study assessed the inclination of the column top, ground displacement, and torsion to analyze the stress and deformation characteristics of PHC pile foundations. The deformation of PHC short pile foundations exhibited distinct phases. Torsional load reduced the column crack load by 30%. The pile cap effectively controlled plastic deformation, minimizing foundation deformation, while torsional load increased lateral deformation. Under cyclic load, the PHC pile behaved with an approximate elasticity characteristic within the test load range. The deformation increased by approximately 10%. Furthermore, three-dimensional numerical simulations analyzed the effects of foundation dimension, bending-moment-to-lateral-load ratio, torque-to-lateral-load ratio, and pile cap size on internal forces and deformation. Simulations indicated that increasing the pile cap length was more advantageous for reducing deformation and internal forces. The bending-moment-to-lateral-load ratio was significant in design, while the torque-to-lateral-load ratio had a negligible impact. A comprehensive design program is proposed based on field tests and numerical simulations, considering deformation and bearing capacity. The study confirms the reliability of the PHC pile foundation as a support structure for heliostats, aiming to offer valuable insights for practical applications.