Finite-Element Model of Impact Loading and Deformation of a Flexible Steel Ring-Net Debris-Flow Barrier

Abstract

The objective of this study is to simulate the stress-displacement behavior of a flexible debris-flow mitigation structure in a three-dimensional finite-element model. Flexible steel ring-net structures are used for debris-flow mitigation in mountainous terrain. Although these structures have been shown effective in geohazard mitigation, their design does not incorporate coupled interactions between debris-flow mechanics and stress-strain response of the steel structure. Thus, a finite-element model was developed to simulate the coupled behavior encountered in a flexible debris-flow mitigation structure. The debris flow was modeled as a series of rectangular solid blocks, and the flexible debris-flow barrier was modeled as a series of rings, cables, and braking elements. Temporal and spatial relationships of cable tension and barrier deformation were compared with a full-scale field experiment from the literature. Barrier deformation along the centerline of the barrier was slightly overpredicted via the numerical model relative to measurements of actual deformation. A fraction of the overprediction was due to differing slope conditions that changed the impact force from the debris flow. However, the shape of the deformed barrier more closely represented actual deformation relative to an analytical model used in the literature. Cable tensions were favorable among measurements from the field, predictions from the numerical developed in this study, and predictions from a published analytical model.