Failure analysis of a transmission tower by non-Newtonian debris flow impact with user-defined SPH particles and finite elements

Abstract

We present numerical methodologies for simulating transmission tower failure under debris flow impacts. To accurately represent the shear-thinning behavior of debris flows, a user-defined Cross rheology model is implemented within the LS-DYNA SPH framework, overcoming limitations of existing built-in materials. The coupled SPH-FEM model captures strain-rate-dependent viscosity and reproduces large deformation and fluid-structure interactions. Structural failure is explicitly modeled through plasticity, energy dissipation, and element erosion, enabling detailed analysis of collapse initiation and progression. Simulations with varying debris flow volumes identify three damage limits (DL1-DL3), corresponding to initial failure, partial member failure, and total collapse of the tower, with critical flow volumes of 2,400, 3,600, and 4,500 m3, respectively. These findings offer practical insights for structural risk assessment in debris flow-prone mountainous regions.