Measurements of hillslope debris flow impact pressure on obstacles

In mountain areas, mass movements, such as hillslope debris flows, pose a serious threat to people and infrastructure, although size and runout distances are often smaller than those of debris avalanches or in-channel-based processes like debris floods or debris flows. Hillslope debris-flow events can be regarded as a unique process that generally can be observed at steep slopes. The delimitation of endangered areas and the implementation of protective measures are therefore an important instrument within the framework of a risk analysis, especially in the densely populated area of the alpine region. Here, two-dimensional runout prediction methods are helpful tools in estimating possible travel lengths and affected areas. However, not many studies focus on 2D runout estimations specifically for hillslope debris-flow processes. Based on data from 19 well-documented hillslope debris-flow events in Switzerland, we performed a systematic evaluation of runout simulations conducted with the software Rapid Mass Movement Simulation: Debris Flow (RAMMS DF)—a program originally developed for runout estimation of debris flows and snow avalanches. RAMMS offers the possibility to use a conventional Voellmy-type shear stress approach to describe the flow resistance as well as to consider cohesive interaction as it occurs in the core of dense flows with low shear rates, like we also expect for hillslope debris-flow processes. The results of our study show a correlation between the back-calculated dry Coulomb friction parameters and the percentage of clay content of the mobilised soils. Considering cohesive interaction, the performance of all simulations was improved in terms of reducing the overestimation of the observed deposition areas. However, the results also indicate that the parameter which accounts for cohesive interaction can neither be related to soil physical properties nor to different saturation conditions.

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Spatial-temporal distribution of debris flow impact pressure on rigid barrier

Journal of Mountain Science ◽

10.1007/s11629-018-5316-4 ◽

2019 ◽

Vol 16 (4) ◽

pp. 793-805 ◽

Cited By ~ 1

Author(s):

Dao-chuan Liu ◽

Yong You ◽

Jin-feng Liu ◽

Yong Li ◽

Guang-ze Zhang ◽

...

Keyword(s):

Debris Flow ◽

Temporal Distribution ◽

Impact Pressure ◽

Rigid Barrier

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

10.31224/osf.io/ne5q6 ◽

2021 ◽

Author(s):

Shuai Li ◽

Chong ◽

Wei Wu ◽

shun wang ◽

Xiaoqing Chen ◽

...

Keyword(s):

Debris Flow ◽

Empirical Relation ◽

Three Dimensional ◽

Numerical Results ◽

Impact Pressure ◽

Jet Flows ◽

Flow Density ◽

Particle Hydrodynamics ◽

Pool System ◽

The Impact

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 ba?es. 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 regularizedBingham model. The SPH method is first checked using the results from two laboratory tests. Then it is used to investigate the influence of bafflee shape and flow density. Numerical results show that the impact pressure at the first ba?e highly depends on the ba?e 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 ba?e 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 ba?e shape is proposed for better prediction of debris impact pressure.

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Centrifuge modelling of hillslope debris flow initiation

CATENA ◽

10.1016/j.catena.2011.12.001 ◽

2012 ◽

Vol 92 ◽

pp. 162-171 ◽

Cited By ~ 12

Author(s):

F.D. Milne ◽

M.J. Brown ◽

J.A. Knappett ◽

M.C.R. Davies

Keyword(s):

Debris Flow ◽

Centrifuge Modelling ◽

Debris Flow Initiation ◽

Hillslope Debris Flow

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Comparing a newly developed DEM-based runout model for hillslope debris flows with full-scale experiments and historical events

10.5194/egusphere-egu2020-19245 ◽

2020 ◽

Author(s):

Adel Albaba ◽

Niels Hollard ◽

Christoph Schaller ◽

Massimiliano Schwarz ◽

Luuk Dorren

Keyword(s):

Debris Flow ◽

Debris Flows ◽

Residential Buildings ◽

Full Scale ◽

Swiss Alps ◽

Model Parameters ◽

Historical Events ◽

Margin Of Error ◽

Hillslope Debris Flow ◽

Good Agreement

The increasing urbanization of mountainous areas increased the risk imposed on residential buildings and infrastructure. In Switzerland, shallow landslides and hillslope debris flows are responsible every year for high infrastructure damage, blocking of important highways, evacuations and deaths. Up till now, the assessment of these processes has been mainly based on the experience of experts, especially in the assessment of their run-out extent and expected damage. In this research we present a new computationally efficient Discrete Element Model (DEM) which has been developed for the aim of simulating the run-out of hillslope debris flows.YADE-DEM open source code has been extended and an elasto-plastic adhesive contact law have been implemented, which partially account for the presence of the fluid composed of water and find material. This is achieved through the adhesive aspect of the contact law, which would indirectly take the presence of such fluid into account, as this fluid would increase the cohesion of the flowing mass. A parametric study has been carried out to define the most sensitive model parameters, which were found to be the microscopic basal friction angle (&#934;b) and the ratio between stiffness parameters (loading and unloading) of the flowing particles <img src="data:image/png;base64,%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" alt="">. Data of full-scale experiments of hillslope debris flows were used to compare the flow kinematics with the model&#8217;s prediction. A good agreement between the model and experiments was observed concerning the mean front velocity (average margin of error of 8%) and the maximum applied pressure (average margin of error of 5%), with less agreement of the flow height (average margin of error of 13%). Detailed comparisons of pressure evolution between different selected experiments and simulations revealed the model&#8217;s capability of reproducing observed pressure curves, especially during the primary loading phase, leading to maximum pressure.In order to test the model&#8217;s prediction of run-out distance of hillslope debris flow, hundreds of past hillslope debris flow events in the Swiss Alps were analyzed and 30 cases were selected representing different situations (i.e. different release volumes, slopes and forest cover). Due to the discrete nature of results in YADE, a GIS algorithm was developed in order to create envelopes representing the temporal evolution of the simulated propagating processes, which were compared to the those of the historical events. Results of the comparison revealed that, with the calibration of the two sensitive parameters in YADE, a fair to very good agreement was observed between the envelopes of the model and those of historical events for 87% of the tested cases. Difficulties in reproducing the envelopes of the rest of the cases are linked to the uncertainties in the mapping of the envelopes of past events, the role of the forest which is not taken into account in the model, and the lack of direct representation of fluid in the model.

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Influence of debris flow solid fraction on rigid barrier impact

Canadian Geotechnical Journal ◽

10.1139/cgj-2016-0502 ◽

2017 ◽

Vol 54 (10) ◽

pp. 1421-1434 ◽

Cited By ~ 29

Author(s):

D. Song ◽

C.W.W. Ng ◽

C.E. Choi ◽

G.G.D. Zhou ◽

J.S.H. Kwan ◽

...

Keyword(s):

Debris Flow ◽

Solid Fraction ◽

Impact Pressure ◽

Frontal Impact ◽

Rigid Barrier ◽

Pile Up ◽

Run Up ◽

The Impact ◽

Fluid Interaction ◽

Fluid Phases

The dynamics of debris flows are fundamentally governed by the interaction between the solid and fluid phases. However, current approaches used to estimate impact load treat debris flow as an equivalent fluid without considering solid–fluid interaction separately from other factors. In this study, a series of centrifuge tests was carried out to investigate the influence of interaction between solid and fluid phases on single-surge debris flow impact on a rigid barrier. The effect of solid–fluid interaction was studied by varying the solid fraction of the flows. A model rigid barrier was instrumented to capture induced bending moment and impact pressure. Test results demonstrate that the transition from a pile-up mechanism to a run-up mechanism is governed by the solid fraction and thus the grain contact stresses. The rigid barrier design for the impact with a pile-up mechanism is mainly dominated by the static load. Contrary to the hydrodynamic approach, which assumes that the frontal impact is the most critical, the frontal impact of a run-up mechanism contributes less than 25% of the total force impulse. The consideration of static loading leads to the development of a new impact model with a triangular distribution of the impact pressure.

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