A new physically based impact model for debris flow

A new analytical model is proposed to estimate the peak impact pressure of debris flow exerted on a rigid barrier. The new model consists of two terms, p = alpha(1)rho(0)gh(0) + 0.5 rho(0)u(0)(2), accounting for static and dynamic impacting effects, respectively. The static coefficient alpha(1) is determined according to equations governing the mass and momentum conservation and energy conservation, and the dynamic coefficient 0.5 is adopted on the basis of the Bernoulli equation. The new analytical model is validated for a wide range of Froude number (Fr) with data collected from past studies on small- scale experiments and field observations and numerical simulations of debris flowas a particle-fluid mixture performed by coupled computational fluid dynamics-discrete-element method (CFD-DEM, for wide-range coverage of Fr). Based on equivalence with the new model, the empirical coefficients involved in conventional pure hydrostatic (k) and pure hydrodynamic (alpha) impact models are found positively and negatively correlated to Fr, respectively. Aunique relationship between k and alpha is further derived: (cos theta/k) + (1/alpha) = 1, where theta denotes slope angle. The underlying physics of this relationship is interpreted. According to the proposed model, a design chart in terms of Fr is further recommended for practical design of debris-resisting barriers. The new analytical model offers a possible improvement on robust and reliable estimation of debris flow impact on a rigid barrier.

Automated summary

A new analytical model has been proposed to estimate the peak impact pressure of debris flow on a rigid barrier, incorporating static and dynamic impacting effects. The coefficients in the model are determined through conservation equations and validated with data from experiments and numerical simulations. The model offers potential improvements for reliable estimation and practical design of debris-resisting barriers.