Stony debris flows,characterized by coarse boulders embedded in a sediment-laden matrix,greatly amplify destructive potential by altering flow dynamics and impact forces.Conventional single-phase particle-fluidmixture...Stony debris flows,characterized by coarse boulders embedded in a sediment-laden matrix,greatly amplify destructive potential by altering flow dynamics and impact forces.Conventional single-phase particle-fluidmixture models often struggle to capture the complexities introduced by coarse boulders and multi-phase interactions,while strong-coupling methods can be computationally prohibitive for practical hazard assessments.In this study,we propose a semi-hybrid,fully resolved coupling numerical framework for modeling boulder-laden debris flows.This framework conceptualizes debris flows as a composite system comprising a continuous viscous fluidphase(including finesediments)and a discrete phase of arbitrarily shaped coarse particles.The continuous phase is treated as a generalized nonlinear Coulomb-viscoplastic fluidusing the smoothed particle hydrodynamics(SPH)method,while coarse particles are modeled via the distributed contact discrete element method(DCDEM).These two phases are coupled through an efficienttwo-way resolved scheme,ensuring accurate simulation of flow-boulder interactions within a unifiedtimeframe.We validate the proposed method against two physical experiments:(1)gravity-driven concrete flows and(2)debris flowinteracting with slit-type barriers.Results confirmthe method's robustness in accurately capturing fluid-solid-structureinteractions and deposition processes.Its capabilities are further showcased through the simulation of a stony debris-flowevent inWenchuan County,China,highlighting its promise for real-world engineering applications and validating the effectiveness of the existing cascade dam system in mitigating debrisflowimpact and energy dissipation.展开更多
Abrasion,a complex physical phenomenon prevalent in natural and engineered structures,frequently causes significant functional failures in drainage channels under the debris flow impact force.This underscores critical...Abrasion,a complex physical phenomenon prevalent in natural and engineered structures,frequently causes significant functional failures in drainage channels under the debris flow impact force.This underscores critical knowledge gaps regarding abrasion effects on debris flow-scoured drainage structures.Through multi-stage field investigations and data analysis across four representative areas,this study proposes a classification system for abrasion phenomena and analyzes morphological characteristics across different drainage structures and debris flow types(rainy vs.glacial).Further,the study methodically uncovers the long-term spatiotemporal distribution,development,and progression of abrasion in drainage channels and check dams.Dynamic abrasion characteristics were evaluated using three key parameters per debris flow:average gully vertical drop,watershed relative cutting degree,and soil sample data.The findings indicate that rainy debris flows exhibit higher average vertical drops(max:0.933)compared to glacial debris flows(max:0.621).Glacial debris flows show greater relative watershed cutting degrees(range:0.15–0.3)than rainy types(range:0.075–0.2).Multiple influencing factors were compared to identify critical controls on abrasion intensity.Debris flow velocity distribution and particle gradation within channels emerged as the primary determinants of abrasion distribution.Notably,a higher proportion of viscous particles(grain size D20%).These findings quantitatively inform the optimization of debris flow mitigation,providing a critical foundation for improving structural design,wear repair techniques,and channel configuration.展开更多
Assessing debris flow susceptibility is crucial for predicting their occurrence and associated hazards.However,traditional methods rely on relatively static environmental conditions,which exposes the lag in the tempor...Assessing debris flow susceptibility is crucial for predicting their occurrence and associated hazards.However,traditional methods rely on relatively static environmental conditions,which exposes the lag in the temporal dynamic changes of debris flow susceptibility assessment.This study focuses on the transition from low to mid mountain terrain located at the southern piedmont of the Yinshan Mountains to a plain within the piedmont clinoplain of the Inner Mongolia Plateau.By integrating the Information Value Method(IVM)and Extreme Gradient Boosting(XGBoost)and utilizing high spatiotemporal surface change data derived from interferometric synthetic aperture radar(InSAR),a new evaluation factor,namely the“basin erosion degree,”is introduced to enhance debris flow susceptibility assessment.The contribution analysis of evaluation results and evaluation factors based on two models shows that IVM and XGBoost identified 90.48%and 95.23%of debris flow gullies in the study area,respectively,and both performed well.XGBoost also performed well in identifying non-debris flow gullies,demonstrating its extremely high accuracy and practicality in assessing debris flow activity in small data scenarios,while IVM misjudged a large number of non-debris flow gullies due to not considering the weight of evaluation factors.Moreover,the newly introduced watershed erosion evaluation factor ranks fourth in the contribution to debris flow,which is of great significance for activity evaluation.The dynamic characteristics of typical debris flow gullies in the study area were simulated using Flo-2D numerical simulation software.The results indicate that mudslides in the area can invade roads,residential buildings,and other facilities,posing a threat to production and daily life.This study accurately assessed the susceptibility of debris flows in the study area by introducing dynamic evaluation factors,making progress in debris flow susceptibility modeling,and promoting the construction of active disaster management systems.展开更多
Debris flow events are frequent in Tajikistan,yet comprehensive investigations at the regional scale are limited.This study integrates remote sensing,Geographic Information System,and machine learning techniques to ev...Debris flow events are frequent in Tajikistan,yet comprehensive investigations at the regional scale are limited.This study integrates remote sensing,Geographic Information System,and machine learning techniques to evaluate debris flow susceptibility and associated hazards across Tajikistan.A dataset comprising 405 documented debris flow points and 14 influencing factors,encompassing geological,climatic-hydrological,and anthropogenic variables,was established.Three machine learning algorithms—Random Forest,Support Vector Machine(SVM),and Multi-layer Perceptron—were applied to generate susceptibility maps and delineate debris flow risk zones.The results indicate that the areas of higher and high susceptibility accounted for 20.43%and 4.41%of the national area,respectively,and were predominantly concentrated along the Zeravshan and Vakhsh river basins.Among the evaluated models,SVM model demonstrated the highest predictive performance.Beyond conventional topographic and environmental controls,drought conditions were identified as a critical factor influencing debris flow occurrence within the arid and semi-arid mountainous regions of Tajikistan.These findings provide a scientific basis for regional debris flow risk management and disaster mitigation planning,and offer practical guidance for selecting conditioning factors in machine-learning-based susceptibility assessments in other dry mountainous environments.展开更多
Post-event debris-flow gullies frequently retain substantial loose material,yet the residual risk they pose is difficult to evaluate due to a scale mismatch:catchment-scale runout models lack the resolution to assess ...Post-event debris-flow gullies frequently retain substantial loose material,yet the residual risk they pose is difficult to evaluate due to a scale mismatch:catchment-scale runout models lack the resolution to assess local structural impacts,while structural-scale models typically rely on idealized inflow conditions.To address this,we develop a crossscale analytical framework applied to Baima Gully along the Jiumian Expressway,which retained abundant loose debris following the 16 August 2020 event.Residual source materials were quantified through field investigations,UAV surveys,highresolution topographic data,and remote-sensing interpretation.The 2020 event was back-analyzed using Mass Flow software to calibrate dynamic parameters,and the validated model was then employed to predict potential residual debris-flow behavior.Resulting hydrographs at the dam site were subsequently used as inputs for fluid-structure interaction simulations in ANSYS CFX and complementary physical flume tests.Mass Flow predictions indicate that a future residual flow could attain a peak velocity of 4.11 m·s-1 near the gully outlet and form a fan-shaped deposit with a maximum flow depth of approximately 5.91 m.Implementation of a proposed solid gravity check dam reduces outlet impact velocity by 49%,decreases inundation area by 41%,and attenuates peak discharge through the spillway by 63.5%.Simulations and flume experiments consistently show that the dam promotes an upstream wedge-shaped deposit,redirects subsequent surge waves,and shifts the peak pressure zone from the dam toe to its mid-height region.Flume measurements reveal a reduction in peak impact pressure from 42.85k Pa to 15.96 k Pa,reflecting a buffering mechanism involving flow redirection,frictional dissipation,and soil arching.Structural verification yields a safety factor of 1.62 for the C25 concrete dam.The proposed framework effectively integrates residual risk prediction,mitigation performance evaluation,and structural response analysis,offering a robust basis for check-dam design in post-event debris-flow gullies along mountainous transport corridors.展开更多
A debris flow descending through an erodible convex colluvial bed,originating from a landslide dam and its upstream deposits,can entrain massive amounts of sediment,dramatically increasing the debris flow volume.Most ...A debris flow descending through an erodible convex colluvial bed,originating from a landslide dam and its upstream deposits,can entrain massive amounts of sediment,dramatically increasing the debris flow volume.Most existing erosion models assume that bed sediments are fully saturated,although this condition is rarely observed in nature.Therefore,a thorough understanding of debris flow overtopping erosion on a convex unsaturated bed is crucial for quantifying disaster risk.In this study,we experimentally investigated the effects of sediment composition,specifically coarse-grain size distribution and fine particle content,on the pore pressure evolution and entrainment of debris flows overriding a convex unsaturated colluvial bed.The average entrainment rate at convex sites for continuously graded bed sediment was higher than its discontinuous counterpart.The measured pore pressures within the unsaturated bed sediments were primarily generated by the passing debris flows.Furthermore,it was found that these pressures decreased as the fine particle content increased and the coarse-grain size of the erodible substrates decreased.When the coarse-grain size of the debris flow was smaller than that of the bed sediment,only a portion of the eroded material was entrained by the moving debris flow.In contrast,when the coarse-grain size of the debris flow was equal to or greater than that of the bed sediment,nearly all of the eroded material was entrained.The findings of this study could contribute to the assessment of hazard amplification and inform the design of mitigation and prevention strategies.展开更多
基金supported by the Japan Society for the Promotion of Science(JSPS)KAKENHI(Grant Nos.JP23KK0182,JP23K26356,and JP24K00971).
摘要Stony debris flows,characterized by coarse boulders embedded in a sediment-laden matrix,greatly amplify destructive potential by altering flow dynamics and impact forces.Conventional single-phase particle-fluidmixture models often struggle to capture the complexities introduced by coarse boulders and multi-phase interactions,while strong-coupling methods can be computationally prohibitive for practical hazard assessments.In this study,we propose a semi-hybrid,fully resolved coupling numerical framework for modeling boulder-laden debris flows.This framework conceptualizes debris flows as a composite system comprising a continuous viscous fluidphase(including finesediments)and a discrete phase of arbitrarily shaped coarse particles.The continuous phase is treated as a generalized nonlinear Coulomb-viscoplastic fluidusing the smoothed particle hydrodynamics(SPH)method,while coarse particles are modeled via the distributed contact discrete element method(DCDEM).These two phases are coupled through an efficienttwo-way resolved scheme,ensuring accurate simulation of flow-boulder interactions within a unifiedtimeframe.We validate the proposed method against two physical experiments:(1)gravity-driven concrete flows and(2)debris flowinteracting with slit-type barriers.Results confirmthe method's robustness in accurately capturing fluid-solid-structureinteractions and deposition processes.Its capabilities are further showcased through the simulation of a stony debris-flowevent inWenchuan County,China,highlighting its promise for real-world engineering applications and validating the effectiveness of the existing cascade dam system in mitigating debrisflowimpact and energy dissipation.
基金supported by the National Natural Science Foundation of China(Grant No.41807300)the Second Tibetan Plateau Scientific Expedition and Research(STEP)Program(Grant No.2019QZKK0902)+2 种基金the National Key Research and Development Program of China(Grant No.2023YFC3007101)the Open Foundation of the Key Laboratory of Life Search and Rescue Technology for Earthquake and Geological Disaster,Ministry of Emergency Management of China(NO.LSR2501)the Research Project of Sichuan Provincial Department of Natural Resources(Grant No.KJ-2024-011)
摘要Abrasion,a complex physical phenomenon prevalent in natural and engineered structures,frequently causes significant functional failures in drainage channels under the debris flow impact force.This underscores critical knowledge gaps regarding abrasion effects on debris flow-scoured drainage structures.Through multi-stage field investigations and data analysis across four representative areas,this study proposes a classification system for abrasion phenomena and analyzes morphological characteristics across different drainage structures and debris flow types(rainy vs.glacial).Further,the study methodically uncovers the long-term spatiotemporal distribution,development,and progression of abrasion in drainage channels and check dams.Dynamic abrasion characteristics were evaluated using three key parameters per debris flow:average gully vertical drop,watershed relative cutting degree,and soil sample data.The findings indicate that rainy debris flows exhibit higher average vertical drops(max:0.933)compared to glacial debris flows(max:0.621).Glacial debris flows show greater relative watershed cutting degrees(range:0.15–0.3)than rainy types(range:0.075–0.2).Multiple influencing factors were compared to identify critical controls on abrasion intensity.Debris flow velocity distribution and particle gradation within channels emerged as the primary determinants of abrasion distribution.Notably,a higher proportion of viscous particles(grain size D20%).These findings quantitatively inform the optimization of debris flow mitigation,providing a critical foundation for improving structural design,wear repair techniques,and channel configuration.
基金supported by the Natural Science Foundation of Jilin Province,China(Grant NO.51420220101158JC).
摘要Assessing debris flow susceptibility is crucial for predicting their occurrence and associated hazards.However,traditional methods rely on relatively static environmental conditions,which exposes the lag in the temporal dynamic changes of debris flow susceptibility assessment.This study focuses on the transition from low to mid mountain terrain located at the southern piedmont of the Yinshan Mountains to a plain within the piedmont clinoplain of the Inner Mongolia Plateau.By integrating the Information Value Method(IVM)and Extreme Gradient Boosting(XGBoost)and utilizing high spatiotemporal surface change data derived from interferometric synthetic aperture radar(InSAR),a new evaluation factor,namely the“basin erosion degree,”is introduced to enhance debris flow susceptibility assessment.The contribution analysis of evaluation results and evaluation factors based on two models shows that IVM and XGBoost identified 90.48%and 95.23%of debris flow gullies in the study area,respectively,and both performed well.XGBoost also performed well in identifying non-debris flow gullies,demonstrating its extremely high accuracy and practicality in assessing debris flow activity in small data scenarios,while IVM misjudged a large number of non-debris flow gullies due to not considering the weight of evaluation factors.Moreover,the newly introduced watershed erosion evaluation factor ranks fourth in the contribution to debris flow,which is of great significance for activity evaluation.The dynamic characteristics of typical debris flow gullies in the study area were simulated using Flo-2D numerical simulation software.The results indicate that mudslides in the area can invade roads,residential buildings,and other facilities,posing a threat to production and daily life.This study accurately assessed the susceptibility of debris flows in the study area by introducing dynamic evaluation factors,making progress in debris flow susceptibility modeling,and promoting the construction of active disaster management systems.
基金supported by the National Natural Science Foundation of China(42361144880)the Science and Technology Program of Xizang Autonomous Region,China(XZ202402ZD0001)the Qinghai Province Basic Research Program Project,China(2024-ZJ-904).
摘要Debris flow events are frequent in Tajikistan,yet comprehensive investigations at the regional scale are limited.This study integrates remote sensing,Geographic Information System,and machine learning techniques to evaluate debris flow susceptibility and associated hazards across Tajikistan.A dataset comprising 405 documented debris flow points and 14 influencing factors,encompassing geological,climatic-hydrological,and anthropogenic variables,was established.Three machine learning algorithms—Random Forest,Support Vector Machine(SVM),and Multi-layer Perceptron—were applied to generate susceptibility maps and delineate debris flow risk zones.The results indicate that the areas of higher and high susceptibility accounted for 20.43%and 4.41%of the national area,respectively,and were predominantly concentrated along the Zeravshan and Vakhsh river basins.Among the evaluated models,SVM model demonstrated the highest predictive performance.Beyond conventional topographic and environmental controls,drought conditions were identified as a critical factor influencing debris flow occurrence within the arid and semi-arid mountainous regions of Tajikistan.These findings provide a scientific basis for regional debris flow risk management and disaster mitigation planning,and offer practical guidance for selecting conditioning factors in machine-learning-based susceptibility assessments in other dry mountainous environments.
摘要泥石流作为高破坏性混合流体,其携带的块石对框架结构的冲击机制尚未得到充分研究。为揭示含块石泥石流冲击框架结构的动力响应与损伤机制,基于光滑粒子流体动力学-离散元法-有限元法(smoothed particle hydrodynamics-discrete element method-finite element method,SPH-DEM-FEM)耦合数值方法,构建流体-块石-结构的多耦合数值模型,模拟不同冲击速度和角度下框架结构的损伤过程,并结合两相溃坝试验来验证模型有效性。研究表明:泥石流冲击导致结构损伤经历“接触-扩散-反弹-堆积/冲击”四个阶段,当冲击速度超过6.00 m/s时,结构产生不可恢复损伤,且块石阻隔作用使流体上部冲击力大于下部,引发结构中部最先发生集中损伤;此外,冲击力峰值随速度和角度增大呈非线性增长,10.00 m/s与90°工况下框架柱底冲击力达497.17 kN,超过结构抗冲击承载力;最后,数值模拟与经验公式所得冲击力结果误差在13.95%~29.00%,数量级一致,验证了模型可靠性。研究结果可为泥石流高发区框架结构的抗冲击设计提供参考。
基金supported by the Open Project Funding of the State Key Laboratory of Safety and Resilience of Civil Engineering in Mountain Area(SQQZ2025128)the Sichuan Science and Technology Program(2025ZNSFSC0331)the Key Research and Development Program of the Tibet Autonomous Region Science and Technology Plan(XZ202402ZY0010)。
摘要Post-event debris-flow gullies frequently retain substantial loose material,yet the residual risk they pose is difficult to evaluate due to a scale mismatch:catchment-scale runout models lack the resolution to assess local structural impacts,while structural-scale models typically rely on idealized inflow conditions.To address this,we develop a crossscale analytical framework applied to Baima Gully along the Jiumian Expressway,which retained abundant loose debris following the 16 August 2020 event.Residual source materials were quantified through field investigations,UAV surveys,highresolution topographic data,and remote-sensing interpretation.The 2020 event was back-analyzed using Mass Flow software to calibrate dynamic parameters,and the validated model was then employed to predict potential residual debris-flow behavior.Resulting hydrographs at the dam site were subsequently used as inputs for fluid-structure interaction simulations in ANSYS CFX and complementary physical flume tests.Mass Flow predictions indicate that a future residual flow could attain a peak velocity of 4.11 m·s-1 near the gully outlet and form a fan-shaped deposit with a maximum flow depth of approximately 5.91 m.Implementation of a proposed solid gravity check dam reduces outlet impact velocity by 49%,decreases inundation area by 41%,and attenuates peak discharge through the spillway by 63.5%.Simulations and flume experiments consistently show that the dam promotes an upstream wedge-shaped deposit,redirects subsequent surge waves,and shifts the peak pressure zone from the dam toe to its mid-height region.Flume measurements reveal a reduction in peak impact pressure from 42.85k Pa to 15.96 k Pa,reflecting a buffering mechanism involving flow redirection,frictional dissipation,and soil arching.Structural verification yields a safety factor of 1.62 for the C25 concrete dam.The proposed framework effectively integrates residual risk prediction,mitigation performance evaluation,and structural response analysis,offering a robust basis for check-dam design in post-event debris-flow gullies along mountainous transport corridors.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1505205)the Science and Technology Research Program of the Institute of Mountain Hazards and Environment,Chinese Academy of Sciences(Grant No.IMHE-ZDRW-01)Sichuan Science and Technology Program(Grant No.2024NSFSC0781).
摘要A debris flow descending through an erodible convex colluvial bed,originating from a landslide dam and its upstream deposits,can entrain massive amounts of sediment,dramatically increasing the debris flow volume.Most existing erosion models assume that bed sediments are fully saturated,although this condition is rarely observed in nature.Therefore,a thorough understanding of debris flow overtopping erosion on a convex unsaturated bed is crucial for quantifying disaster risk.In this study,we experimentally investigated the effects of sediment composition,specifically coarse-grain size distribution and fine particle content,on the pore pressure evolution and entrainment of debris flows overriding a convex unsaturated colluvial bed.The average entrainment rate at convex sites for continuously graded bed sediment was higher than its discontinuous counterpart.The measured pore pressures within the unsaturated bed sediments were primarily generated by the passing debris flows.Furthermore,it was found that these pressures decreased as the fine particle content increased and the coarse-grain size of the erodible substrates decreased.When the coarse-grain size of the debris flow was smaller than that of the bed sediment,only a portion of the eroded material was entrained by the moving debris flow.In contrast,when the coarse-grain size of the debris flow was equal to or greater than that of the bed sediment,nearly all of the eroded material was entrained.The findings of this study could contribute to the assessment of hazard amplification and inform the design of mitigation and prevention strategies.