Research On The Mechanism And Modeling Of Embankment Dam Break Due To Overtopping

The embankment dam is the main dam in reservoir dam,There are many serious dam break accidents in history, and the break dues to overtopping is the important form. At present, the theoretical research and calculation method of the dam break is not mature.This paper analyzes the main modules of the embankment dam break model, summarizes 17 kinds of physically-based model, and introduces the basic principle of BREACH model, MIKE11 DB model and DAMBRK model;Then puts forward a improved model——IWHR DB model, For the further researches on the applicability of scour formula in dam break calculation, basing on IWHR DB model, using MATLAB program, the author writes a dam breach program, including three kinds of erosion formula: Meyer-Peter&Muller bedload formula, Engelund-Hansen bedload formula and hyperbolic formula, to study their impact on the calculation results; Also using the Tangjiashan Landslide dam’s failure data due to overtopping and the two overtopping field test in IMAPCT project studies the applicability and stability of dam break model, and does a detailed sensitivity analysis of the parameters used in the model. All of these provide references for the selection of the model and parameters.; Final basing on the above numerical calculation, puts forward a new method to judge the risk level of landslide dam using the potential energy and dam material. The main conclusions are as follows:(1)The IWHR DB model and BREACH model are conservative, the peak flow error is about 17% and 15% respectively, while the MIKE11 DB model’s results are Relatively small;(2) For landslide dam and Uniform gradation sand dam, the calculation results of Meyer-Peter&Muller are low, the Engelund-Hansen formula has high scour rate, the development of breach is fast and the peak flow is large, the hyperbolic formula are accurate compared with above; for the cohesion dam material, these formula are not ideal.(3) The downstream slope, the uniformity and porosity have a great influence to the BREACH model, the cohesion and angle of internal friction have low impact; The porosity, the initial width of breach and the slope of upstream and downstream are the main sensitivity parameters in MIKE11 DB model, followed by.(4) In the use of IWHR DB model, erosion coefficient is the main sensitivity parameter.(5)The proposed risk classification by potential energy can be more practical for quantifying the break risk for the landslide dam.