A Field Pullout Test to Investigate the Interface of Soil-Nail Inclusion Under Dynamic Loading

Soil-nailed retaining structures have demonstrated remarkable performance in post-earthquake surveys, exhibiting strong stability and deformation control even under significant ground shaking. However, their behavior under dynamic loading is not yet fully understood. The interaction mechanism along the soil–nail interface, particularly the frictional mobilization that governs system stability remains insufficiently explored. This study presents a novel in-situ dynamic pullout testing method developed to investigate the interface behavior of soil–nail inclusions under dynamic loading. The experimental setup integrates a custom dynamic loading system capable of applying controlled cyclic forces, together with high-resolution, real-time displacement monitoring using fiber-optic sensors, allowing precise evaluation of dynamic stiffness and damping characteristics. Six dynamic pullout tests were conducted on nails installed in coarse granular soil under different loading frequencies and amplitudes to examine the influence of excitation parameters on mobilized interface friction. Preliminary results show that the dynamic response of the soil–nail interface is highly sensitive to loading rate, and that interface stiffness increases with nail embedment depth indicating a more rigid behavior at these locations.