Abstract: 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?3 m 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 Ag under small deformation of the pile top are proposed, as well as the empirical methods for obtaining residual deformation.

Key words: pre-stressed high-strength concrete(PHC) short pile foundation, solar power plant, field test, numerical simulation, design method