Study on pile-soil interaction effects of photovoltaic power stations in the Western Sichuan Plateau pastoral area: experiments and numerical simulations

This study addresses the insufficient understanding of pile-soil interaction mechanisms and the lack of engineering validation for pile-soil interface parameters in photovoltaic power stations on the Western Sichuan Plateau pastoral area. Taking the Kela Photovoltaic Power Station as a case study, the research systematically analyzes the physical and mechanical properties of gravelly soils around piles, the pullout bearing characteristics of different pile types, and the inversion and calibration of pile-soil interface parameters using field in-situ tests, laboratory geotechnical experiments, and numerical simulations. The results show that under the field density at the Kela site, gravelly soils exhibit high shear strength. For engineering applications, it is recommended that the cohesion reduction factor be 0.1 to 0.3, and the internal friction angle reduction factor be 0.90. Analysis of field pullout test data from 122 full-scale steel piles reveals differences in load-bearing performance among different pile types: the pullout capacity of steel pipe piles increases approximately 2.6 times as the pile diameter increases from 100 mm to 200 mm, while the ultimate pullout capacity of H-shaped steel piles increases by about 25% as the embedment depth increases from 2.3 m to 3.3 m. The established pile-soil contact model was embedded in the FLAC3D numerical platform, and the pile-soil interface parameters were calibrated using parameter inversion techniques, which effectively reproduced the field load–displacement response. The findings of this study enhance the understanding of pile-soil interaction mechanisms in photovoltaic pile foundations in high-altitude pastoral areas and provide reliable theoretical and parameter support for the analysis and numerical simulation of pullout performance of photovoltaic pile foundations in similar regions.