Role of baffle shape on debris flow impact in step-pool channel: an SPH study

Abstract

Drainage channels with step-pool system are widely used to control debris flow. The blocking of debris flow often gives rise to local damage at the steps and baffles. Hence, the estimation of impact force of debris flow is crucial for designing step-pools channel. Existing empirical models for impact pressure prediction cannot consider the influence of baffle shape. In this work, a three-dimensional smoothed particle hydrodynamics (SPH) study on the impact behaviour of debris flows in step-pool systems is presented, where debris material is modelled using the regularized Bingham model. The SPH method is first checked using the results from two laboratory tests. Then it is used to investigate the influence of baffle shape and flow density. Numerical results show that the impact pressure at the first baffle highly depends on the baffle shape; however, the largest impact pressure usually occurs at subsequent baffles due to the violent impact induced by jet flows. The peak impact pressure at the first baffle initially grows with increasing flow density; however, it starts to drop as density is beyond a threshold. Based on the numerical results, an empirical relation considering the influence of baffle shape is proposed for better prediction of debris impact pressure.

Sensitivity and Calibration of Three‐Dimensional SPH Formulations in Large‐Scale Landslide Modeling

“…A large regularization parameter leads to an extremely large apparent viscosity in the quasi-static flow regime that will severely reduce the numerical efficiency. Several previous test cases (S. Li et al, 2020;Peng et al, 2022) indicate that m = 100 s −1 can correctly simulate landslides. Therefore, in this study, we will set m = 100 s −1 with the RDP model for the Baige landslide.…”

“…(2018) to make sure the simulation results can be the best fit with the field observation data. This optimization method has been used successfully for the analysis of several landslides and debris flows (Coussot, 2017; Dai et al., 2014; S. Li et al., 2020; Yamada et al., 2018). We run a two‐dimensional grid search for both the DP model and the RDP model with the following parameter space: c = 0.1, 1, 5, 10, 15, 20, 25, 30 kPa and tan ϕ between 0.11 and 0.30 with a 0.01 or 0.02 increment (see Table S1 in Supporting Information S1).…”

“…Therefore, in this study, we will set m = 100 s −1 with the RDP model for the Baige landslide. In addition, the pressure ( p ) can be obtained through an equation of state (EOS) based on the weakly compressible assumption (Bui et al., 2008; Huang & Dai, 2014; S. Li et al., 2020; Peng et al., 2019).…”

On three-dimensional SPH modelling of large-scale landslides

“…where c s and ρ 0 are the speed of sound and reference density, respectively. In landslides with considerable water contents and fine particles or under liquifacted state, the mass flow exhibits strong viscous behaviour and are sometimes modelled using the viscoplastic Bingham model [48][49][50]. In the Bingham model, there exists a yield stress τ y which must be exceeded priori to motion.…”

Small-Scale Flume Investigation of the Performance of Step-Baffle Drainage Channels in Mitigating Debris Flows

“…The work proposed design guidelines for the shape and total length of a single step-pool configuration, as well as the slope of the step. Li et al (2020) systematically studied the impact pressure on steps and baffles based on the stability of the drainage channel and recommended an expression to predict impact pressure by considering the baffle shape.…”