Physical modeling and performance-based optimization of interlocking floating-sphere systems for mitigating landslide-generated impulse waves

Landslide-generated impulse waves pose critical threats to reservoir dams in high-mountain canyon environments, yet wave attenuation structures suitable for narrow, confined, and topographically complex settings remain limited. This study develops a large-scale three-dimensional physical model of a typical landslide in the Gushui Reservoir to assess a newly proposed interlocking floating-sphere (IFS) system as a flexible wave attenuation measure. A comprehensive evaluation framework integrating transmission, reflection, and hydrodynamic pressure metrics is established to quantify attenuation performance under various deployment configurations. The experiments reveal five fundamental energy dissipation mechanisms of the IFS: wave overtopping and breakup, turbulence generation, backflow-induced mixing, multipath reflection, and disturbance of water-particle trajectories. Attenuation performance is strongly dependent on deployment position. Near-source placement most effectively reduces overall wave energy, mid-channel placement achieves the highest dissipation efficiency by enhancing breaking and flow-interference processes, and near-dam placement suppresses hazardous right-bank focusing by reshaping the incident wavefront. Multi-row layouts expand the protected area but do not yield additive benefits due to phase interactions among reflected waves. The results demonstrate that the IFS provides an effective and adaptable solution for mitigating impulse waves in mountainous reservoirs and offers practical guidance for optimizing deployment strategies in narrow canyon environments.