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.

A solar power tower plant includes a solar tower and tens of thousands of heliostats, with the latter accounting for 40–50% of the total cost. To reduce heliostat costs, a new type of heliostat support structure (HSS) is proposed, consisting of a prestressed high-strength concrete pipe pile and cast-in-place concrete. With the performance and applicability of this structure unknown, full-scale field load testing of the proposed HSS on coarse gravel, subjected to lateral loads or torsion–lateral combined loads, was conducted. The results indicated that lateral load amplifies the rotation under torque and the proposed HSS for mirror arrays can provide sufficient rigidity to limit structural deformations within tolerable values under severe wind loading. Together with three-dimensional modelling, the performance of the proposed HSS was thoroughly investigated to facilitate the development of modified prediction methods for its lateral and torsional load responses. A detailed design procedure is proposed for the new structure, considering foundation deformations, bearing capacity and survival requirements. This study proved that the proposed HSS can improve the economic performance of solar power tower plants.

The number of power generation elements in a solar power plant is so huge that a small improvement in construction can result in significant cost savings. Therefore, as a new-type supporting structure for the power generation element, the PHC short pile foundation is being continuously improved. The PHC short pile foundation is formed by pouring concrete into the borehole in which a PHC pipe pile is inserted. The interface between the pile and the concrete is usually smooth. The unbalanced wind loads cause the supporting structures to be subjected to cyclic torsional loads. Therefore, the influences of the pipe pile section on the characteristics of the pile-concrete interface and the torsional response of short pile foundation under static or cyclic torsional loads are considered. Ten groups of full-scale model tests on the PHC short pile foundation with round or flanged pile section under different torsional loads are carried out. The test results show that the shallow interface firstly weakens when the torsional deformation of the PHC short pile foundation meets the stage of nonlinear deformation. Under the cyclic torsional loads, the plastic deformation accumulates and eventually leads to concrete cracking. The flange can increase the joint surface between the precast pile and the concrete, which also can provide occlusion between the interface, so as to restrain the development of the plastic deformation and effectively improve the resistance of short pile foundation to the cyclic torsional loads.

The PHC short pile foundation is a new type of supporting structure for the power generation element of a solar power generation station. It is formed by inserting a PHC pipe pile into a hole of 2-3m deep, followed by pouring concrete into the hole. To explore the working behavior of the PHC short pile foundation, field tests were carried out on the sand foundation under the lateral loading, coupled lateral and torsion loading and cyclic loading, respectively. According to the results of inclination of the column top, the displacement at the ground surface and the bending moment along the foundation, the force and deformation characteristics of the PHC short pile foundation and the influence of torsion were analyzed. The influence of pile cap on the inner force and deformation of foundation were then analyzed based on three-dimensional numerical simulation. The results show that the deformation of PHC short pile foundation can be divided into three phases. Torsional loads accelerate the occurrence of the soil plasticity and reduce the crack resistance of pile. The pile cap can efficiently reduce the mudline displacement with little influence on the pile deformation. Under normal ultimate load, the residual deformation after cyclic load is about 2 times of that under single load. Finally, based on the field tests and numerical simulation, the methods for obtaining the proportionality coefficient of horizontal soil resistance coefficient m and proportionality coefficient of soil shear modulus A(g) under small deformation of the pile top are proposed, as well as the empirical methods for obtaining residual deformation.

支撑结构是太阳能电站中用于使发电元件具有一定高度和稳定性的载体.为满足发电元件在运行过程中的强度、刚度要求,并降低支撑结构制造成本,提出了一种立柱与基础一体化的新型支撑结构—短桩基础.短桩基础由PHC管桩作为立柱,并留部分长度伸入钻孔后灌注混凝土作为基础的一部分.针对黄土场地上的短桩基础开展了侧向承载特性现场试验,并研究了桩帽对于提高侧向承载能力的作用.试验结果表明:基础侧向变形在柱顶总变形中占30％以上;承栽力主要由PHC管桩决定;桩帽对于控制极限荷载作用过后的基础残余变形有显著效果,并降低了基础内力.对比相关规范建议的水平桩计算方法,发现k0法可用于黄土场地短桩基础设计,并可通过折减外荷载来考虑桩帽的作用.