ABSTRACT To address transportation and soil disposal challenges in mountainous transmission tower construction with limited equipment access, this study proposes an innovative pile construction methodology integrating prefabricated steel pipe piles with side grouting, namely grouted prefabricated steel pipe pile (GPSPP), to resist wind-induced uplift loads. Comprehensive experiments reveal key findings: (i) interfacial shear tests show soil-grout interfaces exhibit lower strength than natural soils, with failure occurring at soil-grout interfaces rather than grout-steel interfaces; (ii) uplift model tests in plastic clay and gravel-clayey soil demonstrate parabolic shaft resistance distribution, with greater resistance concentration near ground surfaces compared to conventional triangular patterns. Numerical models calibrated with experimental data enable prototype-scale parametric analyses. Pile length, pile diameter, grouting thickness, rock-socket depth, and anchor rod length were evaluated to quantify their influence on ultimate uplift bearing capacity (UBC) of GPSPP. A novel UBC prediction equation of GPSPP incorporating these parameters was proposed and outperforms existing specification methods in reliability tests. The optimized GPSPP methodology enhances uplift resistance while addressing equipment access constraints, providing practical solutions for mountain infrastructure and informing updates to Chinese industry standards. Key innovations include the integrated steel-grout structure design and evidence-based resistance distribution patterns critical for foundation design in complex terrains.
Xu et al. (Fri,) studied this question.