Abstract: Taking the mountainous area of western Sichuan as the study area, this study identifies the distribution characteristics of geological collapse hazards in the region through field investigation and statistical analysis, summarizes two modes of interaction between collapses and transmission towers-impact-collision and traction-and establishes corresponding geomechanical models. Numerical simulation is used to investigate in detail the dynamic response mechanisms of transmission towers and their coupled systems under rockfall impact, revealing the damage threshold of transmission towers and the protective capacity of growth piles under impact. The results show that the dynamic response process can be divided into two stages: elastoplastic indentation and unloading rebound. The damage threshold of the transmission tower is approximately 96 kJ. The damage mode of growth piles changes from localized surface spalling under low impact energy to penetrative perforation under high impact energy, and the energy dissipation mechanism gradually transitions from plastic deformation-dominated to brittle fracture-dominated. The variation in pile-top displacement of growth piles is governed by the respective proportions of energy dissipated by failed concrete elements and the participation of steel reinforcement, and their impact energy capacity can reach 1 500 kJ. Growth piles can be used as a mitigation measure for collapse-induced rockfalls with relatively low post-failure velocity and limited bounce height along transmission line corridors, ensuring the safe and stable operation of transmission engineering.

Key words: collapse, transmission tower, dynamic response, growth pile, prophylactico-therapeutic measures