Post-analysis simulation of the collapse of an open sabo dam of steel pipes subjected to boulder laden debris flow

摘要

The objective of the proposed method is to utilize a site investigation of a debris flow disaster and verify a real scale analysis to evaluate the impulsive load on an open sabo dam.The Nagiso debris flow disaster which occurred in Nagano in 2014,where damage caused by Typhoon Neogri was studied.The verification result of the site investigation demonstrated the weak components of the open Sabo dam experienced damage owing to the debris flow.A discrete element method is normally applied to a solid body to calculate an interaction function force with respect to the contact point between boulders and the dam.The numerical method initially concatenates elements that model the open Sabo dam.Moreover,the stiffness coefficient of flanges and coupling joints between pipes was expressed to utilize the sectional partition method to determine the structural characteristics.The method was improved to separate from the connecting elements beyond the boundary conditions.The debris flow model uses a water flow distribution model,and the debris flow flowed from 200 m upstream of the open sabo dam.Accordingly,the proposed method was examined to verify the primary cause of damage to the open sabo dam and used to reproduce the circumstances that evaluated the impulsive load occurrence mechanism in the case of a real disaster.In addition,the coupling joints between the hollow steel pipes utilized a‘reproduction analysis’for a real sabo dam and a‘reinforced analysis’for a reinforced sabo dam were applied to assess the weak point of the dam.