Experimental testing of flexible barriers for containment of debris flows

The Effects of Upstream Flexible Barrier on the Debris Flow Entrainment and Impact Dynamics on a Terminal Barrier

Canadian Geotechnical Journal ◽

10.1139/cgj-2021-0119 ◽

2021 ◽

Author(s):

Hervé Vicari ◽

C.W.W. Ng ◽

Steinar Nordal ◽

Vikas Thakur ◽

W.A. Roanga K. De Silva ◽

...

Keyword(s):

Debris Flow ◽

Debris Flows ◽

Impact Force ◽

Dynamic Pressure ◽

Pressure Coefficient ◽

Flexible Barrier ◽

Impact Forces ◽

Flexible Barriers ◽

The Impact ◽

Bed Entrainment

The destructive nature of debris flows is mainly caused by flow bulking from entrainment of an erodible channel bed. To arrest these flows, multiple flexible barriers are commonly installed along the predicted flow path. Despite the importance of an erodible bed, its effects are generally ignored when designing barriers. In this study, three unique experiments were carried out in a 28 m-long flume to investigate the impact of a debris flow on both single and dual flexible barriers installed in a channel with a 6 m-long erodible soil bed. Initial debris volumes of 2.5 m3 and 6 m3 were modelled. For the test setting adopted, a small upstream flexible barrier before the erodible bed separates the flow into several surges via overflow. The smaller surges reduce bed entrainment by 70% and impact force on the terminal barrier by 94% compared to the case without an upstream flexible barrier. However, debris overflowing the deformed flexible upstream barrier induces a centrifugal force that results in a dynamic pressure coefficient that is up to 2.2 times higher than those recommended in guidelines. This suggests that although compact upstream flexible barriers can be effective for controlling bed entrainment, they should be carefully designed to withstand higher impact forces.

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Protection against debris flows with 13 flexible barriers in the Milibach River (Canton Berne, Switzerland) and first event analysis

Monitoring, Stimulation, Prevention and Remediation of Dense and Debris Flows IV ◽

10.2495/deb120161 ◽

2012 ◽

Cited By ~ 1

Author(s):

C. Wendeler ◽

B. Vjekoslav

Keyword(s):

Debris Flows ◽

Event Analysis ◽

Flexible Barriers

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A Simplified Analytical Model for the Design of Flexible Barriers Against Debris Flows

Landslide Science for a Safer Geoenvironment ◽

10.1007/978-3-319-05050-8_112 ◽

2014 ◽

pp. 725-730

Author(s):

Andrea Segalini ◽

Roberto Brighenti ◽

Gessica Umili

Keyword(s):

Analytical Model ◽

Debris Flows ◽

Flexible Barriers

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Large Scale Physical Modelling Study of a Flexible Barrier under the Impact of Granular Flows

10.5194/nhess-2018-131 ◽

2018 ◽

Author(s):

Dao-Yuan Tan ◽

Jian-Hua Yin ◽

Wei-Qiang Feng ◽

Jie-Qiong Qin ◽

Zhuo-Hui Zhu

Keyword(s):

Debris Flows ◽

Large Scale ◽

Impact Force ◽

Granular Flows ◽

Physical Modelling ◽

Flexible Barrier ◽

Impact Forces ◽

Flexible Barriers ◽

Open Question ◽

The Impact

Abstract. Flexible barriers are being increasingly applied to mitigate the danger of debris flows. However, how barriers can be better designed to withstand the impact loads of debris flows is still an open question in natural hazard engineering. Here we report an improved large-scale physical modelling device and the results of two consecutive large-scale granular flow tests using this device to study how flexible barriers react under impact from granular flows. In the study, the impact force directly on the flexible barrier and the impact force transferred to the supporting structures are measured, calculated and compared. Based on the comparison, the impact loading attenuated by the flexible barrier is quantified. The hydro-dynamic and hydro-static approaches are also validated using the calculated impact forces.

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Large-scale physical modelling study of a flexible barrier under the impact of granular flows

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-2625-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 2625-2640 ◽

Cited By ~ 7

Author(s):

Dao-Yuan Tan ◽

Jian-Hua Yin ◽

Wei-Qiang Feng ◽

Jie-Qiong Qin ◽

Zhuo-Hui Zhu

Keyword(s):

Debris Flows ◽

Large Scale ◽

Impact Force ◽

Granular Flows ◽

Physical Modelling ◽

Flexible Barrier ◽

Static Approach ◽

Flexible Barriers ◽

Open Question ◽

The Impact

Abstract. Flexible barriers are being increasingly applied to mitigate the danger of debris flows. However, how barriers can be better designed to withstand the impact loads of debris flows is still an open question in natural hazard engineering. Here we report an improved large-scale physical modelling device and the results of two consecutive large-scale granular flow tests using this device to study how flexible barriers react under the impact of granular flows. In the study, the impact force directly on the flexible barrier and the impact force transferred to the supporting structures are measured, calculated, and compared. Based on the comparison, the impact loading attenuated by the flexible barrier is quantified. The hydro-dynamic approaches with different dynamic coefficients and the hydro-static approach are validated using the measured impact forces.

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Coupling Depth-Averaged and 3D models for debris flow: a multi-domain strategy

10.5194/egusphere-egu21-4501 ◽

2021 ◽

Author(s):

Andrea Pasqua ◽

Alessandro Leonardi ◽

Marina Pirulli

Keyword(s):

Debris Flow ◽

Lattice Boltzmann Method ◽

Lattice Boltzmann ◽

Debris Flows ◽

Laboratory Tests ◽

3D Model ◽

Fluid Structure Interaction ◽

Structure Interaction ◽

Flexible Barriers ◽

Boltzmann Method

Debris flows are landslide phenomena which occur worldwide, posing a major threat to mountain settlements. They consist of flowing fine and coarse sediment saturated with water, which propagate mainly in channelized paths. Because of their high velocity and unpredictability, the evacuation of local populations is often impossible. Losses of human lives and economical damages can be avoided if a correct risk mitigation procedure is adopted. Hence, mitigation structures, such as filter barriers or flexible barriers are often installed in high-risk areas. The primary goal of these structures is to reduce the flow energy and to retain the coarsest boulders. Their design process, which is still frequently based only on empirical or simplified models, would greatly benefit from the support of a reliable numerical model.&#160;In this framework, continuum-based Depth-Averaged Models (DAMs) have been the dominant numerical tool since the 90s. DAMs can simulate events propagating over a wide area while keeping the computational time low, even on complex topographies (Pirulli, 2010). Nevertheless, the averaging process applied to velocity and pressure causes a loss of information, which is critical when the flow impact against structures is evaluated. A full 3D model would allow for a more accurate resolution of fluid-structure interaction (Leonardi et al., 2016). However, debris flows may propagate up to kilometres, and a complete 3D analysis would therefore require exceedingly long computational times.&#160;To bypass the shortcomings mentioned above, this work aims to couple DAMs to a 3D model based on the Lattice Boltzmann Method (LBM). Thus, the domain is split into two parts. First, DAMs describes the flow evolution from its initialization to the transport phase. In this portion of the domain, no structures are present. When the flow approaches a structure, DAMs is coupled to a 3D model. To verify the coupling procedure accuracy, the model is benchmarked on the laboratory tests conducted by Moriguchi et al. (2009). These laboratory tests targeted the flow of dry sand on a steep chute, evaluating the flow impact on a barrier. Preliminary results suggest that the coupled model reproduces the laboratory results reasonably well.&#160;Keywords: debris flow, coupled numerical modelling, depth-averaged method, 3D Lattice-Boltzmann Method&#160;REFERENCESLeonardi, A., Wittel, F. K., Mendoza, M., Vetter, R., & Herrmann, H. J. (2016). Particle-Fluid-Structure Interaction for Debris Flow Impact on Flexible Barriers. Computer-Aided Civil and Infrastructure Engineering, 31(5), 323&#8211;333.Moriguchi, S., Borja, R. I., Yashima, A., & Sawada, K. (2009). Estimating the impact force generated by granular flow on a rigid obstruction. Acta Geotechnica, 4(1), 57&#8211;71.Pirulli, M. (2010). On the use of the calibration-based approach for debris-flow forward-analyses. Natural Hazards and Earth System Science, 10(5), 1009&#8211;1019.

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