A study of the baffle pile application as a mitigation method of debris flow hazard was done by utilizing a Coupled Eulerian-Lagrangian method, with a Herschel-Bulkley fluid as the material definition. A sealed physical model test involving rigid barrier and baffle pile layouts is being numerically modeled in ABAQUS/Explicit. A thorough validation was made to confirm that the result produced by the model is reasonable. This study was done with multiple variables in the investigation, including models with different: 1) slope inclination, 2) baffle pile installation location, 3) baffle pile layout, and 4) baffle pile geometry. The investigation result confirms that adding baffle piles decreases the rigid barrier impact force by up to 38.8% and reduces the kinetic energy of the granular flow by around 61%. Placing the baffle pile in a higher position produces more delay in arrival time, while putting the baffle pile closer to the rigid barrier diminishes the baffle piles' effectiveness. However, by considering the overall performance of the baffle piles, placing them in between the rigid barrier and the granular material’s initial location is considered optimum. A steep inclination may cause the material to jump after it interacts with the baffle piles; this phenomenon must be addressed during the design of the baffle pile system. Different baffle pile shapes produce a different flow separation, affecting the general performance of the baffle piles. To summarize, the optimized setup for the baffle pile system is by putting the diamond baffle pile in the middle of the runoff area but with careful attention to the change in granular material’s flow behavior caused by the interaction with the baffle piles.

Alexandrou, A. N., McGilvreay, T. M., and Burgos, G. (2001).“Steady Herschel-Bulkley fluid flow in three-dimensional expansions.” Journal of Non-Newtonian Fluid Mechanics, 100(1–3).

Asay, J. R., and Shahinpoor, M. (1993).High-Pressure Shock Compression of Solids. High-Pressure Shock Compression of Solids.

Bi, Y., Sun, X., Zhao, H., Li, Q., He, K., Zhou, R., and Ji, W. (2021).“Comparison Regarding the Effects of Different Baffle Systems as Impacted by Rock Avalanches.” International Journal of Civil Engineering, 19(2).

Bi, Y. Z., Du, Y. J., He, S. M., Sun, X. P., Wang, D. P., Li, X. P., Liang, H., and Wu, Y. (2018).“Numerical analysis of effect of baffle configuration on impact force exerted from rock avalanches.” Landslides, 15(5).

Bi, Y. Z., He, S. M., Du, Y. J., Sun, X. P., and Li, X. P. (2019).“Effects of the configuration of a baffle–avalanche wall system on rock avalanches in Tibet Zhangmu: discrete element analysis.” Bulletin of Engineering Geology and the Environment, 78(4).

Boslough, M. B., and Asay, J. R. (1993).“Basic Principles of Shock Compression.” High-Pressure Shock Compression of Solids.

Bugnion, L., McArdell, B. W., Bartelt, P., and Wendeler, C. (2012).“Measurements of hillslope debris flow impact pressure on obstacles.” Landslides, 9(2).

Ceccato, F., Redaelli, I., diPrisco, C., and Simonini, P. (2018).“Impact forces of granular flows on rigid structures: Comparison between discontinuous (DEM) and continuous (MPM) numerical approaches.” Computers and Geotechnics, 103.

Chen, H., and Lee, C. F. (2004).“Geohazards of slope mass movement and its prevention in Hong Kong.” Engineering Geology, 76(1–2).

Chen, W., and Qiu, T. (2012).“Numerical Simulations for Large Deformation of Granular Materials Using Smoothed Particle Hydrodynamics Method.” International Journal of Geomechanics, 12(2).

Choi, C. E., Cui, Y., Liu, L. H. D., Ng, C. W. W., and Lourenço, S. D. N. (2017).“Impact mechanisms of granular flow against curved barriers.” Geotechnique Letters, 7(4).

Choi, C. E., and Law, R. P. H. (2015).“Performance of landslide debris-resisting baffles.” HKIE Transactions Hong Kong Institution of Engineers, 22(4).

Choi, C. E., Ng, C., Law, R., Song, D., Kwan, J., and Ho, K. (2014a).“Computational investigation of baffle configuration on impedance of channelized debris flow.” Canadian Geotechnical Journal, 52(2).

Choi, C. E., Ng, C. W. W., Song, D., Kwan, J. H. S., Shiu, H. Y. K., Ho, K. K. S., and Koo, R. C. H. (2014b).“Flume investigation of landslide debris-resisting baffles.” Canadian Geotechnical Journal, 51(5).

Cosenza, E., Cozzolino, L., Fabbrocino, G., and Pianese, D. (2006).“Concrete Structures for Mitigation of Debris-flow Hazard in the Montoro Inferiore Area , Southern Italy.” Fédération Internationale du Béton Proceedings of the 2nd International Congress, 2(June).

Crosta, G. B., Imposimato, S., and Roddeman, D. (2009).“Numerical modeling of 2-D granular step collapse on erodible and nonerodible surface.” Journal of Geophysical Research: Solid Earth, 114(3).

Cui, Y., Choi, C. E., Liu, L. H. D., and Ng, C. W. W. (2018).“Effects of particle size of mono-disperse granular flows impacting a rigid barrier.” Natural Hazards, 91(3).

Cuomo, S., Cascini, L., Pastor, M., and Petrosino, S. (2017).“Modelling the Propagation of Debris Avalanches in Presence of Obstacles.” Advancing Culture of Living with Landslides.

Faug, T. (2015).“Depth-averaged analytic solutions for free-surface granular flows impacting rigid walls down inclines.” Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 92(6).

Faug, T., Childs, P., Wyburn, E., and Einav, I. (2015).“Standing jumps in shallow granular flows down smooth inclines.” Physics of Fluids, 27(7).

Hákonardóttir, K. M., Hogg, A. J., Jóhannesson, T., and Tómasson, G. G. (2003).“A laboratory study of the retarding effects of braking mounds on snow avalanches.” Journal of Glaciology, 49(165).

Horiguchi, T., and Komatsu, Y. (2019).“Method to evaluate the effect of inclination angle of steel open-type check dam on debris flow impact load.” International Journal of Protective Structures, 10(1).

Hsu, T. Y. (2020).“Validating and Appliying Coupled Eulerian-Lagrangian Technique: Benchmark exercise for characterizing granular flows (Master’s Thesis).” National Cheng Kung University.

Hübl, J., Suda, J., Proske, D., Kaitna, R., and Scheidl, C. (2009).“Debris Flow Impact Estimation.” International Symposium on Water Management and Hydraulic Engineering, (September), 137–148.

Iverson, R. M. (1997).“The physics of debris flows.” Reviews of Geophysics, 35(3).
Jianbo, F., Yuxin, J., Xiaohui, S., and Xi, C. (2020).“Experimental investigation on granular flow past baffle piles and numerical simulation using a μ(I)-rheology-based approach.” Powder Technology, 359.

Karlsson, H., and Sorensen. (2019).“ABAQUS/Explicit: user’s manual.” Hibbitt, Karlsson & Sorensen, Inc.

Kasai, M., Ikeda, M., Asahina, T., and Fujisawa, K. (2009).“LiDAR-derived DEM evaluation of deep-seated landslides in a steep and rocky region of Japan.” Geomorphology, 113(1–2).

Kattel, P., Kafle, J., Fischer, J. T., Mergili, M., Tuladhar, B. M., and Pudasaini, S. P. (2018).“Interaction of two-phase debris flow with obstacles.” Engineering Geology, 242.

Kwan, J. S. H., Sze, E. H. Y., and Lam, C. (2019).“Finite element analysis for rockfall and debris flow mitigation works.” Canadian Geotechnical Journal, 56(9).

Law, R. P. H., Choi, C. E., and Ng, C. W. W. (2016).“Discrete-element investigation of influence of granular debris flow baffles on rigid barrier impact.” Canadian Geotechnical Journal, 53(1).

Lee, K., and Jeong, S. (2019).“Analysis of the impact force of debris flows on a check dam by using a coupled Eulerian-Lagrangian (CEL) method.” Computers and Geotechnics, Elsevier Ltd, 116.

Lee, K., and Jeong, S. (2020).“Numerical Analysis on the effect of bed-sediment entrainment by debris flow.” (In Review), 31.

Lee, K., Kim, Y., Ko, J., and Jeong, S. (2019).“A study on the debris flow-induced impact force on check dam with- and without-entrainment.” Computers and Geotechnics, 113.

Leonardi, A., Wittel, F. K., Mendoza, M., Vetter, R., and Herrmann, H. J. (2016).“Particle-Fluid-Structure Interaction for Debris Flow Impact on Flexible Barriers.” Computer-Aided Civil and Infrastructure Engineering, 31(5).

Li, X., Yan, Q., Zhao, S., Luo, Y., Wu, Y., and Wang, D. (2020).“Investigation of influence of baffles on landslide debris mobility by 3D material point method.” Landslides, 17(5).

Li, X., and Zhao, J. (2018).“Dam-break of mixtures consisting of non-Newtonian liquids and granular particles.” Powder Technology, 338.

Lin, C. H., Hung, C., and Hsu, T. Y. (2020).“Investigations of granular material behaviors using coupled Eulerian-Lagrangian technique: From granular collapse to fluid-structure interaction.” Computers and Geotechnics, 121.

Liu, W., Yan, S., and He, S. (2020).“A simple method to evaluate the performance of an intercept dam for debris-flow mitigation.” Engineering Geology, 276.

Lu, J.-Y. (2005).“Debris Flow.” Encyclopedia of Soil Science, Second Edition, T.Takahashi, ed., CRC Press, London, 465.

Luong, T. H., Baker, J. L., and Einav, I. (2020).“Spread-out and slow-down of granular flows through model forests.” Granular Matter, 22(1).

Major, J. J. (1997).“Depositional processes in large-scale debris-flow experiments.” Journal of Geology, 105(3).

Mast, C. M., Arduino, P., Miller, G. R., and Mackenzie-Helnwein, P. (2014).“Avalanche and landslide simulation using the material point method: flow dynamics and force interaction with structures.” Computational Geosciences, 18(5).

McCaffrey, W., Kneller, B., and Peakall, J. (2001).Particulate Gravity Currents. Particulate Gravity Currents.

Moriguchi, S., Borja, R. I., Yashima, A., and Sawada, K. (2009).“Estimating the impact force generated by granular flow on a rigid obstruction.” Acta Geotechnica, 4(1).

Ng, C. W. W., Choi, C. E., Kwan, J. S. H., Koo, R. C. H., Shiu, H. Y. K., and Ho, K. K. S. (2014).“Effects of Baffle Transverse Blockage on Landslide Debris Impedance.” Procedia Earth and Planetary Science, 9, 3–13.

Ng, C. W. W., Choi, C. E., Kwan, J. S. H., Shiu, H. Y. K., Ho, K. K. S., and Koo, R. C. H. (2012).“Flume Modelling of Debris Flow Resisting Baffles.” Proceedings of the One Day Seminar On Natural Terrain Hazard Mitigation Measures, C. K.Lau, E.Chan, and J.Kwan, eds., The Association of Geotechnical and Geoenvironmental Specialists (Hong Kong) Limited, Kowloon, 16–21.

Ng, C. W. W., Choi, C. E., Song, D., Kwan, J. S. H., Koo, R. C. H., Shiu, H. Y. K., and Ho, K. K. S. (2013).“Physical modeling of baffles influence on landslide debris mobility.” Landslides.

Proske, D., Suda, J., and Hübl, J. (2011).“Debris flow impact estimation for breakers.” Georisk, 5(2).

Qiu, G., Henke, S., and Grabe, J. (2011).“Application of a Coupled Eulerian-Lagrangian approach on geomechanical problems involving large deformations.” Computers and Geotechnics, 38(1).

Schimmel, A., and Hübl, J. (2016).“Automatic detection of debris flows and debris floods based on a combination of infrasound and seismic signals.” Landslides, 13(5).

Shen, W., Zhao, T., Zhao, J., Dai, F., and Zhou, G. G. D. (2018).“Quantifying the impact of dry debris flow against a rigid barrier by DEM analyses.” Engineering Geology, 241.

Siyou, X., Lijun, S., Yuanjun, J., Xin, Q., Min, X., Xiaobo, H., and Zhenyu, L. (2020).“Experimental investigation on the impact force of the dry granular flow against a flexible barrier.” Landslides, 17(6).

Song, D., Ng, C. W. W., Choi, C. E., Zhou, G. G. D., Kwan, J. S. H., and Koo, R. C. H. (2017).“Influence of debris flow solid fraction on rigid barrier impact.” Canadian Geotechnical Journal, 54(10).

Takahashi, T. (2001).“Process of Occurrence, Flow and Deposition of Viscous Debris Flow.” River, Coastal and Estuarine Morphodynamics.

Takahashi, T. (2021).“Models for mechanics of flow.” Debris Flow.

Tayyebi, S. M., Pastor, M., and Stickle, M. M. (2021).“Two-phase SPH numerical study of pore-water pressure effect on debris flows mobility: Yu Tung debris flow.” Computers and Geotechnics, 132.

Troncone, A., Conte, E., and Pugliese, L. (2019).“Analysis of the slope response to an increase in pore water pressure using the material point method.” Water (Switzerland), 11(7).

Vagnon, F. (2020).“Design of active debris flow mitigation measures: a comprehensive analysis of existing impact models.” Landslides, 17(2).

Venugopal, V. (2002).“Hydrodynamic Force Coefficients for Rectangular Cylinders in Waves and Currents.” University of Glaslow.
Wang, M., Lu, Z., Wan, W., and Zhao, Y. (2021).“A calibration framework for the microparameters of the DEM model using the improved PSO algorithm.” Advanced Powder Technology, 32(2).

Wei, Z., Yin, G., Wang, J. G., Wan, L., and Jin, L. (2012).“Stability analysis and supporting system design of a high-steep cut soil slope on an ancient landslide during highway construction of Tehran-Chalus.” Environmental Earth Sciences, 67(6).

Wendeler, C., Volkwein, A., Roth, A., Denk, M., and Wartmann, S. (2007).“Field measurements used for numerical modelling of flexible debris flow barriers.” International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction, and Assessment, Proceedings.

Wijaya, C. (2020).“Quantifying the Destructive Impact Reduction of Granular Material with Baffle Piles using CEL (Master’s Thesis).” National Cheng Kung University.

Wu, Y. H., Liu, K. F., and Chen, Y. C. (2013).“Comparison between FLO-2D and Debris-2D on the application of assessment of granular debris flow hazards with case study.” Journal of Mountain Science, 10(2).

Yang, X., Zeng, X., Chen, H., Wang, Y., He, L., and Wang, F. (2019).“Molecular dynamics investigation on complete Mie-Grüneisen equation of state: Al and Pb as prototypes.” Journal of Alloys and Compounds, 808.

Yuce, M. I., and Kareem, D. A. (2016).“A numerical analysis of fluid flow around circular and square cylinders.” Journal - American Water Works Association, 108(10).