Debris Flow Impact Research Articles

Cause Analysis and Preventive Measures of Guizhou D2809 Train Derailment Accident in Guizhou, China on 4 June 2022.

This paper summarizes the cause of the debris flow impact train accident by investigating the local geological condition, meteorological data and field investigation that happened in Guizhou, China on 4 June 2022. The result showed that the major reason is the continuous heavy rain in the surrounding area, which led to a small landslide at the upper right of the tunnel entrance. Besides, the construction of the Jianrong Expressway in the upper reaches increased the catchment area, which makes the water content of the upper soil increase while the shear strength decreases. Such large-scale catastrophic accidents significantly threaten the local environment and public safety. Therefore, it is urgent to pay special attention to the changes in geological conditions along the line, especially the adverse effects of construction, to improve the early risk warning and post-accident treatment ability.

Bidirectional Coupling Analysis of Support Pipeline for Shock Damping of Dilute Debris Flow

With the frequent occurrence of geological disasters and extreme weather, pipeline failure accidents and secondary disasters caused by debris flow continue to occur. Aiming at the impact of thin debris flow on support pipeline, a multi-physical coupling model of debris flow and support pipeline with vibration reduction is established based on the expansion flow model. The expansive fluid model is used to simulate the stress of the support pipeline under the action of thin debris flow. The results show that the impact effect of thin debris flow slurry on the support pipeline is concentrated at the inlet surface of the pipeline and the support, and gradually decreases to both ends. As the velocity of debris flow slurry increases, the stress acting on the support pipeline also increases. When the flow field tends to be stable, the load acting on the support pipeline maintains a stable value. The leading effect of debris flow slurry is the most serious damage to the support pipeline. The research results have a certain reference value for the impact of dilute debris flow in support pipeline.

Debris Flow Prediction Based on the Fast Multiple Principal Component Extraction and Optimized Broad Learning

In the current research of debris flow geological disaster prediction, determining reasonable disaster-inducing factors and ensuring the accuracy and rapidity of the prediction model are considered vital issues, and also, essential foundations for disaster early warning and disaster prevention and mitigation. Aiming at the problems of low prediction accuracy and long prediction time in the current debris flow research, firstly, six debris flow impact factors were selected relying on the fast multiple principal component extraction (FMPCE) algorithm, including rainfall, slope gradient, gully bed gradient, relative height difference, soil moisture content and pore water pressure. Next, based on the broad learning (BL) algorithm, the debris flow prediction model based on FMPCE and the optimized BL is established with the input of debris flow-inducing factors and the output of debris flow probability. Then the model is optimized using matrix stochastic approximate singular value decomposition (SVD), and the debris flow disaster prediction model, based on SVDBL, is constructed. The prediction results of the optimized model are compared with those of the gradient descent optimized the BP neural network model(GD-BP), Support Vector Machines model(SVM) based on grid search and BL model. The results show that the accuracy of SVDBL is 7.5% higher than that of GD-BP, 3% higher than that of SVM and 0.5% higher than that of BL. The RMSE sum of SVDBL was 0.05870, 0.0478 and 0.0227 less than that of GD-BPSVM and BL, respectively; the MAPE sum of SVDBL was 1.95%, 1.66% and 0.49% less than that of GD-BPSVM and BL; the AUC values of SVDBL were 12.75%, 7.64% and 2.79% higher than those of the above three models, respectively. In addition, the input dataset is expanded to compare the training time of each model. The simulation results show that the prediction accuracy of this model is the highest and the training time is the shortest after the dataset is expanded. This study shows that the BL can be used for debris flow prediction, and can also provide references for disaster early warning and prevention.

Numerical simulation of impact and entrainment behaviors of debris flow by using SPH–DEM–FEM coupling method

Abstract Increasing rain levels can easily destabilize and destroy particulate matter in mountainous areas, which can cause natural disasters, such as debris flow and landslides. Constitutive equations and numerical simulation are the theoretical bases for understanding the behavior of these disasters. Thus, this study aimed to investigate the impact of the debris flow and its entrainment behavior on gully bed sediments. We adopted a coupled analysis method based on elastic–plastic constitutive equations by considering the elasto-plasticity of slurry and the elastic characteristics of debris materials. The coupled method consisted of smooth particle hydrodynamic (SPH), discrete element method (DEM), and finite element method (FEM) (SPH–DEM–FEM). SPH particles represented fluid, DEM particles denoted solid immersed in fluid, and FEM elements represented the terrain and structures. The coupling analysis model was used to simulate the coupling contact of solid, liquid, and structures and to describe the entrainment behavior between solid and liquid phases. The model feasibility was verified by comparing the basic simulation results with experimental values of the dam break model and the rotating cylindrical tank model. The coupled model was then combined with the data management and modeling of geographic information system to simulate the 2010 Yohutagawa debris flow event. Finally, we explored the influence of debris shape-related parameters on the debris flow erosion entrainment process.

Examining the effect of Debris Flow on Oil and Gas Pipelines Using Numerical Analysis

This article examines the impact of debris flow on semi-exposed pipelines to determine the plastic deformation and stresses by considering pipe-debris flow interaction. A 3-D finite element approach was adopted to study the mechanical behavior of pipelines subjected to debris flow. Integration of pipeline property (thickness) with debris flow intensity (impact pressure and angle) was also considered in a finite element numerical model for semi-exposed. The analysis showed that the impact angle between 35° and 75° with an impact pressure of 200 kPa and 250 kPa significantly affected the stability and integrity of the pipeline. There was a slight impact of wall thickness on the stability of the pipeline due to the passive soil resistance. Maximum plastic deformation of 124 mm was encountered in the case of 35° impact angle, which was 3% more than the deformation observed at 20° impact angle. Moreover, large distribution of von mises stresses was observed, as 1390 Mpa, 1450 Mpa, 1440 Mpa, and 1440 Mpa for impact angles of 20°, 35°, 75°, and 90° in the impacted zone of the pipeline in each set of analysis. Shear failure of the pipeline was observed during the analysis as von misses’ stresses were more than the yield stress (520 Mpa) of the pipeline. The developed model in this study can be utilized for further research and will be a basis for designing pipelines crossing through mountainous regions.

Analytical and numerical models of debris flow impact

A full understanding of the interaction mechanisms among flow-like landslides and impacted protection structures is still an open issue. Although several approaches, from experimental to numerical, have been used so far, a thoroughly assessment of the hydromechanical behaviour of the landslide body is achievable only through a multiphase and large deformation approach.This paper firstly proposes a conceptual model for a specific type of protection structure, namely a Deformable Geosynthetics-Reinforced Barrier (DGRB), i.e., an embankment made of coarse-grained soil layers reinforced by geogrids. In such a case, the sliding of the barrier along its base, under the impulsive action of a flow-type landslide, is an important landslide energy dissipation mechanism, and a key issue for the design. Then, two different approaches are proposed: i) an advanced hydro-mechanical numerical model based on Material Point Method is tested in simulating the whole complex landslide-structure interaction mechanisms, ii) an analytical model is set up to deal with the landslide energy dissipation and the kinematics of both the landslide and barrier. The calibration of the proposed analytical model is pursued based on the numerical results. Finally, the analytical model is successfully validated to interpret a large dataset of landslide impact field evidence, for whose interpretation also five empirical methods available in the literature are tested.

Dynamics of bouldery debris flow impacting onto rigid barrier by a coupled SPH-DEM-FEM method

Boulders entrained in debris flows can often generate destructive impact forces and cause damages to rigid barriers. In this study, a large-scale numerical flume model based on the smoothed particle hydrodynamics (SPH), the discrete element method (DEM) and the finite element method (FEM) is established to investigate the impact of bouldery debris flow onto a rigid barrier. The numerical model is first validated with the reported experimental data, in terms of the impact force, the displacement of boulder and flow front. The numerical model is then used to investigate the dynamic interaction between bouldery debris flow and rigid barrier, the energy dissipation of the boulder and the mechanism of buffering effect of debris flow. The numerical results show that the debris slurry can provide a buffering effect to the boulder by reducing the boulder kinetic energy. The buffering effect decreases with the channel slope. Based on the numerical results, a load reduction factor is recommended to consider the buffering effect. The findings of this study can provide some references for the design of rigid barrier.

Influence of Debris-Flow Impact on the Structural Stability of Check Dams

Small check dams are widely used in the Republic of Korea to mitigate and prevent sediment-driven damages by mountain torrents. This study aimed to quantify the combined effects of debris-flow impact forces and earth pressures from dam sedimentations on the structural stability of a dam by incorporating the change in the longitudinal profile of the channel bed owing to sediment deposition. A debris-flow simulation model (Hyper Kanako) was used to reproduce the debris-flow behavior from the 2011 Mt. Umyeon landslide (Seoul, The Republic of Korea). Finite element analysis was conducted to analyze the structural stability of the check dam under various debris discharge and sedimentation scenarios. The magnitudes of impact forces that were exerted on the check dam ranged from 81.76 kPa under a non-deposition scenario to 123.04 kPa under a 100% deposition scenario. The resultant tensile and compressive stresses were found to be up to 0.80 and 0.35 MPa, respectively, which were lower than the maximum allowable strengths of the dam, securing sufficient strength for the dam stability. Overall, the proposed approach can be applied to obtain a better understanding of the resultant internal stresses experienced during debris flow and sediment deposition, thereby providing valuable information for the structural analysis and safety assessment of check dams.

Calculation of the Overall Coordination Internal Force of the Grille Beam-Column under the Impact of Debris Flow

At present, the research on the new ground anchor counterfort grille dam is not perfect. In order to analyze and design the new grille dam accurately and reasonably, it is necessary to carry out theoretical research on the internal force calculation of the overall coordination of the grille beam-column under the impact of debris flow. Under the condition of full reservoir of debris flow, the grille beam-column meets the working principle of elastic foundation beam; therefore, the equation of the overall cooperative work of the grille beam-column is derived based upon Winkler’s theory of elastic foundation beam. Finally, combined with the engineering example, this calculation method is used for analysis; the results show that the bending moment of the grille beam-column increases compared with that regardless of considering the overall coordination, and the increased value of the bending moment at the bottom of the grille column and the middle of the grille beam is the largest. Therefore, from the perspective of safety, the overall coordination cannot be ignored when designing a blocking dam.

Ecosystem carbon stock loss after a mega earthquake

Earthquake-induced geohazards, in particular landslides and debris flows, have the ability to disturb large stocks of organic carbon. Even a slight change in these stocks of organic carbon could affect atmospheric CO2 concentrations. Yet, the fate of ecosystem carbon delivery caused by a mega-earthquake over a short timescale is not well understood. In this study, a methodology is proposed to study the impact of earthquake-triggered landslides and post-seismic debris flows on ecosystem carbon (C). Pairs-plots were established on undisturbed areas, coseismic landslides or debris flow in one of the most representative catchments, in the 2008 Wenchuan earthquake hit regions. Results showed that coseismic landslides greatly reduced vegetation C stock from 34.48 Mgha-1 to 6.85 Mgha-1 and soil C stock from 96.38 to 6.77 Mgha-1, thereby leading to 89.6% reduction for total ecosystem C stock. Similarly, debris flow deposit led to a reduction of 97.8% of ecosystem C stock. Overall, it is estimated that there was a loss of 0.118×106Mg C across the study area, indicating a large amount of carbon change after the mega-earthquake. This study has an important implication for the role of mega-earthquake on regional ecosystem C storage and fills our knowledge gaps of the impact of ecosystem C cycle along with earthquake-induced geohazard chains.

Reliability-based vulnerability analysis of bridge pier subjected to debris flow impact

In this paper, a finite element model of a highway bridge pier subjected to debris flow is established, which comprises a double-column pier, a gully channel, moving fluid and solid particles. By using the arbitrary Lagrangian-Eulerian (ALE) algorithm to calculate the fluid-solid coupling effect, the process of debris flow impacting on the pier is simulated. Based on the ‘two-phase flow’ theory, a simplified equation to calculate the impact force of debris flow containing both fluid and solid phases is proposed, and the variable parameters in the equation are determined through numerical simulation using the established FE model and the field-measured data. By comparing with the historical records of actual debris flows, the effectiveness of the numerical model and the proposed equation is verified. A reliability model of the pier subjected to debris flow is established, and the structural vulnerability is estimated by the MCS method. Using the site-observed data, the failure mode of a highway double-column pier subjected to impact of two-phase debris flow is studied. The critical velocities of debris flow causing the structure to have different modes of damage, and the critical impact height of debris flow on the pier suffering bending and shear failures are determined.

Effect of Boulder Size on Debris Flow Impact Pressure Using a CFD-DEM Numerical Model

Debris flows (DFs) are dangerous events that can cause the complete destruction of buildings and infrastructure, such as bridges; DFs therefore represent a high risk to public safety in exposed areas. The impact pressures due to these flows are essentially determined by the flow height, velocity and density, but other parameters that are less often considered are also involved. We developed a numerical model to evaluate the impact pressure of mass flows, focusing on a better description of the influence of the blocks transported in these flows: the block size strongly influences the impact pressure, which has a strong effect on structural damage. The numerical model proposed considers a staggered, loosely one-way granular–fluid coupling based on a distinct-element-method code, using the separate simulation results of a computing fluid dynamics code used to model the fluid phase. This model estimates the impact pressure distribution due to blocks at the local scale of the obstacle; the pressure due to the fluid phase can be added afterwards. The pressure applied by the DF increased with the maximum block size for a given set of DF characteristics: velocity, height and apparent density. The vulnerability of a given structure depends on the intensity of DFs: the pressure applied on the structure is one of considerable intensity. The existing vulnerability functions are interpreted in the light of the results obtained with the numerical model. This interpretation highlights the need to integrate new parameters in the intensity to better evaluate structures’ vulnerability to debris flows.

Empirical formulation for debris flow impact and energy release

Full understanding the interaction mechanisms between flow-like landslides and the impacted protection structures is an open issue. While several approaches, from experimental to numerical, have been used so far, it is clear that the adequate assessment of the hydromechanical behaviour of the landslide body requires both a multiphase and large deformation approach. This paper refers to a specific type of protection structure, namely a rigid barrier, fixed to the base ground. Firstly, a framework for the Landslide-Structure-Interaction (LSI) is outlined with special reference to the potential barrier overtopping (nil, moderate, large) depending on the features of both the flow and the barrier. Then, a novel empirical method is casted to estimate the impact force on the barrier and the time evolution of the flow kinetic energy. The new method is calibrated by using an advanced hydro-mechanical numerical model based on the Material Point Method. The validation of the empirical formulation is pursued referring to a large dataset of field evidence for the peak impact pressure. Both numerical and empirical methods can appropriately simulate the physical phenomena. The performance of the newly proposed empirical method is compared to the literature methods and its advantages are outlined.

A scaling law for designing a downscaled model to investigate submarine debris-flow impact on a pipeline in normal gravity

In recent years, many downscaled physical hydraulic tests and Computational Fluid Dynamics (CFD) numerical simulations in normal-gravity environments have been conducted to study the submarine debris-flow impact on a pipeline. However, a lack of model-prototype similarity has inhibited robust applications of the downscaled models. In this study, the pressing issue of model-prototype similarity is addressed. The debris flow is described as a Herschel–Bulkley fluid. The generic scaling law is derived based on the Reynolds similarity criterion, and its applicability is demonstrated by a series of CFD models carefully designed to simulate laminar fluids passing downscaled and prototype pipelines. The scaling law is found to be completely applicable to design a downscaled model of a Newtonian fluid passing a pipeline, whereas it is limited to the design of a downscaled model of Power-law or Herschel–Bulkley fluids passing a pipeline with shear strain rates below a critical value. Beyond this value, the downscaled model will overestimate the drag and lift coefficients and underestimate the Strouhal number. Results from a number of numerical simulations prove that the scaling law provides a basis for the design of a downscaled model of debris-flow impact on a pipeline in normal-gravity environments.

Environmental and economic impact of cloudburst-triggered debris flows and flash floods in Uttarakhand Himalaya: a case study

This paper examines the environmental and economic impact of cloudburst-triggered debris flow and flash flood in four villages of Uttarkashi district, Uttarakhand Himalaya. On 18th July 2021 at 8:30 p.m., a cloudburst took place on the top of the Hari Maharaj Parvat, which triggered a huge debris flows and flash floods, affecting 143 households of four villages of downstream areas. Immediately after the cloudburst occurred, the authors visited four affected villages—Nirakot, Mando, Kankrari, and Siror. A structured questionnaire was constructed and questions were framed and asked from 143 heads of affected households on the impact of debris flows and flash floods on people’s life, settlements, cowsheds, bridges, trees, forests, and arable land in and around the villages. The volume of debris, boulders, pebbles, gravels, and mud was assessed. It was noticed that all four villages got lots of destructions in terms of loss of life—people and animals, and property damage—land, crops, and infrastructural facilities. This study shows that the location of the settlements along with the proximity of the streams, which are very violent during the monsoon season, has led to the high impact of debris flow on the affected villages. We suggest that the old inhabited areas, which are located in the risk zones, can be relocated and the new settlements can be constructed in safe places using suitability analyses.

Study on Dynamic Response of Blocking Structure and Debris Flow Impulsive Force considering Material Source Erosion

Abstract The erosion of debris flows on the material source will affect the movement and impact of the debris flow. This paper adopted the coupled SPH-DEM-FEM to establish a complex dynamic model of the particle-fluid-erosion-structure of the debris flow and to assess the impact of erosion and sedimentation and analyse the dynamic response of the retaining structure of the debris flow. The strain-softening model was adopted to simulate the transformation of the debris flow body from the solid state to the transition state and finally into the liquid state. The coupled numerical analysis completely reproduces the debris flow erosion test, fitting the debris flow shape and thickness profile well. The impact process of the debris flow, the impact height behind the retaining dam, the deposition thickness, and the debris flow dynamic response significantly influence both with and without considering the effects of erosion. The results of this study are similar to existing literature and data, with the numerical analysis being consistent with the physical simulation tests in the existing literature, verifying the applicability of the SPH-DEM-FEM coupling analysis for assessing the debris flow impact retaining structures of erosion and sedimentation. The study also found that the dynamic response considering the debris flow impact and the retaining structures of erosion and sedimentation is more pronounced than when not considering erosion and sedimentation. Coupled numerical analysis can assess the potential effect of erosion and sedimentation, making a significant contribution to the assessment of the impact of debris flow and the design of retaining structures.

Effects of Barrier Stiffness on Debris Flow Dynamic Impact—I: Laboratory Flume Test

Debris flows often cause local damage to engineering structures by exerting destructive impact forces. The debris-flow–deformable-barrier interaction is a significant issue in engineering design. In this study, a large physical flume model test device was independently designed to repeatedly reproduce the flow and impact process of debris flow. Three physical flume tests were performed to investigate the effect of barrier stiffness on the debris flow impact. The flow kinematics of debris flow with three barrier stiffness values are essentially consistent with the process of impact–run-up–falling–pile-up. The development of a dead zone provided a cushion to diminish the impact of the follow-up debris flow on the barrier. The peak impact forces were attenuated as the barrier stiffness decreased. The slight deflections of a deformable barrier were sufficiently effective for peak load attenuation by up to 30%. It showed that the decrease of the barrier stiffness had a buffer effect on the debris flow impact and attenuated the peak impact force. And with the decrease of the barrier stiffness, when the barrier was impacted by the same soil types, the recoverable elastic strain will be larger, and the strain peak will be more obvious.

Simulation of debris flows in the watershed of the Putih River, Indonesia using SIMLAR 2.1

In 2010, the eruption of Mount Merapi produced a huge volcanic material for debris flows. One area affected by the debris flows is the watershed of Putih River. To predict the impact caused by debris flows can be done by using software such as the Simulation Lahar (SIMLAR) 2.1. In this paper, debris flow modelling will be carried out using SIMLAR 2.1 in conditions without sabo dams and using sabo dams. This simulation aims to determine the effectiveness of the sabo dams in reducing the impact of debris flows. The data used are rainfall data, DEM and sediment data in Putih River. The results show that the sabo dam building can slow down the velocity of debris flow. In addition, sabo dams also function as a barrier to riverbed erosion in the Putih River watershed. Based on the results above, it can be concluded that SIMLAR 2.1 can predict the impact of debris flows in the Putih River watershed.

Two-phase SPH modelling of a real debris avalanche and analysis of its impact on bottom drainage screens

Rapid flow-like landslides, particularly debris flows and debris avalanches, cause significant economic damage and many victims worldwide every year. They are usually extremely fast with the capability of travelling long distances in short times, sweeping away everything in their path. The principal objective of this paper is to test the ability of the ‘GeoFlow-SPH’ two-phase model developed by the authors, to reproduce the complex behaviour of natural debris avalanches where pore-water pressure evolution plays a key role. To reach this goal, the model is applied to reproduce the complex dynamic behaviour observed in Johnsons Landing debris avalanche including the observed bifurcation caused by the flowing out of part of the moving mass from the mid-channel. Initial thickness deposit trim-line, distribution of deposit volume, and the average velocities were provided for this real case, making it an appropriate case to validate the developed model. The paper also contributes to evaluate the SPH-FD model’s potentialities to simulate the structural countermeasure, like bottom drainage screens, used to reduce the impact of debris flows. The analysis of the results shows the adequacy of the proposed model to solve this complicated geophysical problem.

Analysis on the mechanical properties of the crossbeam of a new ground anchor counterfort grille dam considering bearings displacement

Aiming at the problem that the uneven deformation of the crossbeam of the new ground anchor counterfort grille dam under the impact of debris flow is easy to cause the overall damage of the structure, the crossbeam is simplified as a mechanics model of multi − span continuous beam supported on the grille columns, and the internal force calculation formulas of the crossbeam under the displacement and the local failure of the bearings are deduced. Combined with an example, during the process of bearings from the displacement to local failure, the internal force variation of the crossbeam are analyzed. The results show that when the single bearing is displaced, the mid − span bearing has the greatest impact on the internal force of the crossbeam. When the two bearings are displaced at the same time, the two side − span bearings have a greater influence on the internal force of the crossbeam. When three bearings are displaced at the same time, the influence on the internal force of the crossbeam is the smallest. When the single bearing fails, the failure of side − span bearing has the greatest influence on the internal force of the crossbeam, the mid − span bearing failure is second. Therefore, the reinforcement at each bearing of the crossbeam should be considered to meet the force requirements after the internal force redistribution in the design, so as to ensure the safety of the structure after the positive and negative bending moment of bearing are converted. In addition, when displacement or failure of bearings occur, attention should be paid to meet the limit requirements of structural deformation and stability. The research results can provide a theoretical basis for the reliability analysis of the new ground anchor counterfort grille dam.