Runout Behavior Research Articles

Investigation and dynamic analyses of rockslide-induced debris avalanche in Shuicheng, Guizhou, China

On July 23, 2019, a large catastrophic landslide occurred in Shuicheng, Guizhou, China. It was a rapid and long run-out landslide that resulted in more than 50 casualties. The displaced materials traveled an approximate distance of 1250 m, with a descending height of around 465 m. In this paper, seismic record analyses and numerical simulation were conducted to determine the run-out behavior of the Shuicheng landslide. To determine the main characteristics of the landslide, geological and climatic settings were obtained by conducting a detailed field survey. The DAN3D model was used to simulate the propagation and run-out process of the landslide. It was observed that a combined Frictional-Voellmy model provides assuring results in simulating the Shuicheng landslide. The total duration of the landslide is 60 s with an average velocity of 20 m/s. The maximum velocity is estimated to be 40 m/s along the right bank of the valley, while a high initial velocity of 24 m/s was recorded at the initiation of the landslide. Seismic records obtained from the nearby seismic stations were used to calculate the location of the event and interpret the dynamic process of the landslide. The Arias intensity, Hilbert-Huang transform, and Empirical mode decomposition were used to obtain a detailed time history of the landslide. The results of the numerical simulation and seismic record analyses are expected to portray the process of similar landslides. This will improve the accuracy of landslide hazard mapping in the region.

Experiments on the sedimentation front in steady particle-driven gravity currents

We present an experimental investigation of steady particle-driven gravity currents with Reynolds numbers in the range 500–1600, and with the ratio of the initial current speed to the fall speed of the particles, S = u 0 /u fall , in the range 5 < S < 160. We identify three regimes: (i) For S < 10, the particles settle close to the source at a velocity corresponding to their fall speed, consistent with the observation of sedimenting fronts in classical settling column experiments. (ii) In the range 10 < S < 40, a steady gravity current develops within the tank. The experiments show that the depth of the gravity current gradually decreases away from the source and dye added to the source liquid appears above the gravity current along its entire length, suggesting that there is a sedimentation front, so that the volume and momentum fluxes of the current gradually decrease with distance from the source. We find that as S increases, the descent speed of the sedimentation front decreases relative to the fall speed of the particles, and the run-out length of the gravity current increases. We note that the density of the interstitial fluid corresponds to the density of the ambient fluid, so that any reduction in buoyancy of the gravity current is attributed to the sedimentation of particles on the floor of the tank and we do not observe lofting of the interstitial fluid. (iii) For 40 < S < 160, the gravity currents reach the end of our experimental tank and we no longer observe a sedimentation front. For these experiments, it appears that the entrainment at the top of the current begins to match the sedimentation and so the current depth does not change significantly over the scale of the tank, but a larger scale experimental system would be needed to explore the full run-out behaviour for these larger values of S. For the intermediate case, 10 < S < 40, we develop a model for the conservation of volume, momentum and buoyancy fluxes in the current, accounting for the sedimentation front and the release of fluid at the top surface of the gravity current, and we compare this with our new experimental data.

The energy reduction factor (FER) to model sensitive clay flowslides using in situ geotechnical and rheological data

Sensitive clays, mostly found in Eastern Canada and Scandinavia, are prone to various types of landslides; among them are flowslides that may affect hectares of land. Debris from those slides has high mobility, with runout distances that may extend over hundreds of meters in relatively flat and non-channelized terrain. Most studies on the mobility use apparent rheological properties to back-calculate the runout behavior of these landslides. This works well for back-analyses of landslides but is of little help in a context of hazard mapping, where prospective analysis of future landslides is necessary. In this study, a new factor, using the destructuration index concept, is introduced to estimate the remaining energy available as kinetic energy for runout after the remolding of the sensitive clay: the energy reduction factor (FER). Using the FER allows the use of real rheological data acquired with a rheometer to analyze the post-failure behavior of a flowslide in sensitive clays. This method is applied on a sensitive clay landslide which took place in Quebec and where rheological and geotechnical data are available.

Forecasting Landslides via Three-Dimensional Discrete Element Modeling: Helong Landslide Case Study

Forecasting the occurrence potential of landslides is important but challenging. We aimed to forecast the failure potential of the Helong landslide, which is temporarily stable but has clearly deformed in recent years. To achieve the goal, we used reconnaissance, remote sensing, drilling, laboratory tests, topographical analysis, and electrical resistivity tomography (ERT). The factor of safety (FOS) of the slope was first calculated using a limit equilibrium method. The results show the FOS of the slope was 1.856 under natural conditions, 1.506 under the earthquake conditions, 1.318 under light rainfall, 0.986 under heavy rainfall, 1.075 under light rainfall and earthquake, and 0.832 under simultaneous heavy rainfall and earthquake. When the FOS is less than 1.35, the slope is considered metastable according to the Technical Code for Building Slope Engineering (GB50330-2013) published by the Chinese Ministry of Housing and Urban-Rural Development. Based on the drilling data and digital elevation data, a three-dimensional discrete element method (DEM) model was used to simulate potential landslides. The simulation was used to examine catastrophic slope failure under heavy rainfall conditions within a range of friction coefficients and the corresponding affected areas were determined. Then, we analyzed a typical run-out process. The dynamic information of the run-out behavior, including velocity, run-out distance, and depth, were obtained, which is useful for decision support and future landslide hazard assessment.

Three-dimensional material point method modeling of runout behavior of the Hongshiyan landslide

This study presents a field-scale simulation of the Hongshiyan landslide in China. It uses an advanced numerical approach (material point method (MPM)) and a constitutive model (the Drucker–Prager model + μ(I) rheological relation) for the three-dimensional (3D) simulation. The performance of the developed MPM model is validated with laboratory-scale experimental data on granular collapse before being applied to field-scale analyses. ArcGIS data are used to create a 3D MPM model of the soil body with complicated geometry. Although the developed model can describe the multiple phases of granular flow, it focuses on the runout behavior of the landslide in this work. The landslide is assumed to have occurred suddenly due to an earthquake, and global sudden failure rather than progressive failure is modeled. The MPM simulation results match reasonably well with the measured post-earthquake topography (e.g., deposit height of about 120 m and stretch length of about 900 m in the river) and landslide duration of about 1 min. The velocity of the sliding mass increases rapidly during flow, especially in the first 20 s. The velocity profiles along the depth direction at different locations of the sliding body exhibit an exponential distribution similar to that of a Bagnold-type profile, indicating that the sliding body is fully mobilized. The rate-dependent dissipation parameter β used in the model significantly influences the runout behavior (e.g., flow speed, velocity distribution, and deposit shape).

Numerical investigation of the air blast generated by the Wenjia valley rock avalanche in Mianzhu, Sichuan, China

On 12 May 2008, a catastrophic rock avalanche was triggered by an earthquake in Mianyang, Sichuan, China. This catastrophic event killed 48 people and destroyed some houses at the mouth of Wenjia valley. The sliding mass caused a powerful air blast that blew down the trees on both sides and front margin. To better understand the possible mechanism of the air blast generated by the Wenjia valley rock avalanche and provide information for the assessment of this type of disasters in southwestern China, a numerical simulation was performed through a computational fluid dynamics software (Fluent) to simulate the runout behavior of the sliding mass and dynamic characteristics of the air blast. The frictional rheology is used for the source area and the Voellmy model is selected for the erosion and deposition areas. Simulated results indicate that the movement process of Wenjia valley rock avalanche lasted approximately 210 s with a maximum velocity of 65 m/s. The maximum velocity and relative pressure of the air blast are 35 m/s and 2.25 kPa, respectively. Furthermore, the variation of topography has a significant effect on the distribution of relative pressure for the air blast. The work conducted in this study is expected to make people deeply realize the disaster caused by the air blast and establish a risk assessment system in the southwestern China.

Investigation and dynamic analysis of the catastrophic rockslide avalanche at Xinmo, Maoxian, after the Wenchuan Ms 8.0 earthquake

At 5:38:58 a.m. on June 24, 2017, a catastrophic rockslide avalanche occurred at the Xinmo village, Diexi town, Maoxian county, Sichuan Province, and the area could have been deeply affected by many strong earthquakes in history. The landslide killed 83 people and destroyed the whole village, with the runout horizontal distance of about 2800 m and the elevation difference of 1200 m, which was equivalent to a Fahrboschung of about 23°, and the accumulative volume reached nearly 18 million m3. The field investigation and preliminary analysis of landslide seismic signals indicated that, after sliding from the ridge crest, the rock mass continuously impacted and accumulated on the upper part of the slope, which caused the substrate, i.e., old rockslide accumulation, to slide and disintegrate. It was transformed rapidly into a pipeline-type debris avalanche that then turned into a fan-like debris flow due to the terrain, which also had the typical dynamic characteristics of high speed and long runout. However, in fact, as the cause and effect of the kinematic and dynamic processes of the Xinmo landslide is so complicated and difficult to understand, the Fast Lagrangian Analysis of Continua (FLAC) and the slope-stability analysis module of GeoStudio were firstly combined to analyze the failure process of the old rockslide accumulation body when suffering the added forces from the landslide. Then, the Engineering Discrete Element Method (EDEM) was used to simulate the runout behavior of the displaced landslide materials, the calculated velocity value of which was also compared with those using other dynamic modeling approaches (e.g., sled model, rheological model, and liquefied model). The results demonstrate that the dynamic characteristics and the kinetic type of the Xinmo landslide were successfully simulated. Besides, the velocity values simulated by EDEM and by the rheological model were close to the value of around 60 m/s based on the distance of debris avalanche and the corresponding duration recognized through landslide seismic signals. Also, their velocity variation curves with motion were rational. The above proposed method can be further applied for studies on early recognition and hazard zonation of similar large-scale rockslide avalanches in areas affected by strong earthquakes.

Characteristics and runout behaviour of the disastrous 28 August 2017 rock avalanche in Nayong, Guizhou, China

On 28th August 2017, a disastrous rock avalanche occurred in Nayong, Guizhou, China. This catastrophic event killed 35 people and destroyed 23 houses. In this study, the failure process of the avalanche was analyzed using UAV video footage and seismic signal recordings obtained for the pre- and post-failure stages of the landslide. To better understand the possible mechanism of the avalanche and its dynamic characteristics, a numerical simulation was conducted using a dynamic model (DAN3D) to simulate the runout behaviour of the displaced materials. Simulated results indicate that the failure process of the Nayong rock avalanche lasted approximately 30 s; the duration of the failure process is close to that from the UAV video footage and seismic signal recordings (35 s). The duration of movement during the landslide process is estimated to be approximately 90 s with a maximum velocity of 40 m/s. The combined frictional-Voellmy model delivered the most accurate results when simulating this event. The selected models and parameters are expected to aid in clarifying the propagation processes of similar rock avalanches and thus improve the accuracy of hazard prediction in mountainous karst areas.

Field characterisation and numerical modelling of debris avalanche runout on Vancouver Island, British Columbia, Canada

This study presents the results from field characterisation and runout modelling of debris avalanches from Vancouver Island, British Columbia. Information about the terrain attributes at the initiation, transport and deposition zones of 44 debris avalanches (30 to 9000 m3 in volume) is presented. The slope angle at the initiation point of the debris avalanches was found to be independent of the volume of the failure; the termination slope angle did however show a dependence on the debris avalanche volume. Grain size distribution and soil classification were conducted on till and colluvium samples collected from the initiation zones and the failed material classified as well-graded gravels with a low plasticity fine-grained component. Field measurements of the runout path geometry dimensions for 31 slope failures were used to conduct back-analyses. The dynamic analysis code DAN-W was used to determine rheological input parameters for debris avalanche while the modelled runout distance using the empirical-statistical code UBCDFLOW was compared to field observations. The results of the back-analysed rheological parameters were compared against published values for debris and rock avalanches. Based on the DAN-W results, the debris avalanches from Vancouver Island were found to have higher effective friction angle values than the published back-calculated values for large rock avalanches. UBCDFLOW was able to closely model the runout behaviour of most debris avalanches investigated.

Extracting region-specific runout behavior and rainfall thresholds for massive landslides using seismic records: a case study in southern Taiwan

Typhoon Morakot struck Taiwan on 7 August 2009, bringing severe rainfall and landslides. Of the many landslides caused by the storm, 12 large-scale landslides were discovered based on seismic signals recorded from broadband seismic stations. Landslides inventoried from both seismic records and satellite imagery are used as baseline data to evaluate region-specific forensic analyses of landslide features, e.g. disturbed area, width and runout distance (Drunout), associated with landslide-induced seismic signals and signal durations (Δt). The results of these analyses show that (i) the landslide-disturbed area correlated well with signal duration when Δt was over 60 s; (ii) the landslide-disturbed area correlated well with the ratio of the landslide width to runout distance when Δt was under 40 s; (iii) the runout distance of sliding mass exhibited a positive relation with Δt2, satisfying the energy conserved during mass movement. This case study presents a region-specific examination of the Δt-Drunout relationship based on 12 large-scale landslides that occurred during Typhoon Morakot, providing insight into the sliding processes. In addition, the time of landslide initiation was extracted from seismic signals in order to better understand region-specific, large-scale, landslide rainfall thresholds. These relationships indicate that (a) long-duration rainstorms with high cumulative rainfall tend to dictate the occurrence of large-scale landslides; (b) the rainfall threshold for large-scale landslides is found to be higher than in previous studies that also include smaller landslides, defined in this region as I = 60D−0.31, where I is the rainfall intensity (mm/h) and D is the duration (h) of the rainstorm.

The Aso-Bridge coseismic landslide: a numerical investigation of failure and runout behavior using finite and discrete element methods

The complex coseismic process of the Aso-Bridge landslide during the main shock of the 2016 Kumamoto Earthquake was investigated. Finite element analysis and discrete element analysis considering vertical seismic accelerations (VSA) were conducted to explore the salient features of the prefailure mechanism and postfailure kinematic process of the coseismic landslide associated with the initiation time and kinematic runout behavior, respectively. Two seismic input conditions, one involving only horizontal seismic accelerations (HSA), and the other accounting for both HSA and VSA, were used to assess the influence of VSA from the prefailure to postfailure regimes. First, satisfactory agreement between the study and the published results in terms of landslide initiation time was obtained. As revealed by the rapid change of source displacement (RCSD), VSA did not alter landslide initiation time; however, it significantly increased the RCSD approximately 2-fold, which provided a clear initiation time. At landslide initiation, the estimated average velocities in a vertical direction increased approximately 16-fold (from −0.011 to −0.174 m/s) by accounting for VSA. Second, the results suggested that VSA had a trivial influence on runout behavior in the postfailure regime, given that such behavior was dominated by the collision and free fall during the sliding as well as the terrain features. With an average velocity of 21.34 m/s, the sliding source ultimately reached the riverbank within 21 s. The paper demonstrates that a combination of FEA and DEA can be used to investigate the coseismic process of the Aso-Bridge landslide and lead to satisfactory agreement with the event. Our comprehensive analysis provides insight into the role of VSA in earthquake-induced landslides.

Mechanics of granular column collapse in fluid at varying slope angles

This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. 2-D sub-grain scale numerical simulations are performed to understand the flow dynamics of granular collapse in fluid. The discrete element method (DEM) technique is coupled with the lattice Boltzmann method (LBM), for fluid-grain interactions, to understand the evolution of submerged granular flows. The fluid phase is simulated using multiple-relaxation-time LBM (LBM-MRT) for numerical stability. In order to simulate interconnected pore space in 2-D, a reduction in the radius of the grains (hydrodynamic radius) is assumed during LBM computations. The collapse of granular column in fluid is compared with the dry cases to understand the effect of fluid on the runout behaviour. A parametric analysis is performed to assess the influence of the granular characteristics (initial packing) on the evolution of flow and run-out distances for slope angles of 0°, 2.5°, 5° and 7.5°. The granular flow dynamics is investigated by analysing the effect of hydroplaning, water entrainment and viscous drag on the granular mass. The mechanism of energy dissipation, shape of the flow front, water entrainment and evolution of packing density is used to explain the difference in the flow characteristics of loose and dense granular column collapse in fluid.

Mechanics of granular column collapse in fluid at varying slope angles

This paper investigates the effect of initial volume fraction on the runout characteristics of collapse of granular columns on slopes in fluid. Two-dimensional sub-grain scale numerical simulations are performed to understand the flow dynamics of granular collapse in fluid. The Discrete Element (DEM) technique is coupled with the Lattice Boltzmann Method (LBM), for fluid-grain interactions, to understand the evolution of submerged granular flows. The fluid phase is simulated using Multiple- Relaxation-Time LBM (LBM-MRT) for numerical stability. In order to simulate interconnected pore space in 2D, a reduction in the radius of the grains (hydrodynamic radius) is assumed during LBM computations. The collapse of granular column in fluid is compared with the dry cases to understand the effect of fluid on the runout behaviour. A parametric analysis is performed to assess the influence of the granular characteristics (initial packing) on the evolution of flow and run-out distances for slope angles of 0°, 2.5°, 5° and 7.5°. The granular flow dynamics is investigated by analysing the effect of hydroplaning, water entrainment and viscous drag on the granular mass. The mechanism of energy dissipation, shape of the flow front, water entrainment and evolution of packing density is used to explain the difference in the flow characteristics of loose and dense granular column collapse in fluid.

Characteristics and numerical runout modeling of the heavy rainfall-induced catastrophic landslide–debris flow at Sanxicun, Dujiangyan, China, following the Wenchuan Ms 8.0 earthquake

The 2008 Ms 8.0 Wenchuan earthquake triggered a large number of extensive landslides. It also affected geologic properties of the mountains such that large-scale landslides followed the earthquake, resulting in the formation of a disaster chain. On 10 July 2013, a catastrophic landslide–debris flow suddenly occurred in the Dujiangyan area of Sichuan Province in southeast China. This caused the deaths of 166 people and the burying or damage of 11 buildings along the runout path. The landslide involved the failure of ≈1.47 million m3, and the displaced material from the source area was ≈0.3 million m3. This landslide displayed shear failure at a high level under the effects of a rainstorm, which impacted and scraped an accumulated layer underneath and a heavily weathered rock layer during the release of potential and kinetic energies. The landslide body entrained a large volume of surface residual diluvial soil, and then moved downstream along a gully to produce a debris flow disaster. This was determined to be a typical landslide–debris flow disaster type. The runout of displaced material had a horizontal extent of 1200 m and a vertical extent of 400 m. This was equivalent to the angle of reach (fahrboschung angle) of 19° and covered an area of 0.2 km2. The background and motion of the landslide are described in this study. On the basis of the above analysis, dynamic simulation software (DAN3D) and rheological models were used to simulate the runout behavior of the displaced landslide materials in order to provide information for the hazard zonation of similar types of potential landslide–debris flows in southeast China following the Wenchuan earthquake. The simulation results of the Sanxicun landslide revealed that the frictional model had the best performance for the source area, while the Voellmy model was most suitable for the scraping and accumulation areas. The simulations estimated that the motion could last for ≈70 s, with a maximum speed of 47.7 m/s.

Collapse of tall granular columns in fluid

Avalanches, landslides, and debris flows are geophysical hazards, which involve rapid mass movement of granular solids, water, and air as a multi-phase system. In order to describe the mechanism of immersed granular flows, it is important to consider both the dynamics of the solid phase and the role of the ambient fluid. In the present study, the collapse of a granular column in fluid is studied using 2D LBM - DEM. The flow kinematics are compared with the dry and buoyant granular collapse to understand the influence of hydrodynamic forces and lubrication on the run-out. In the case of tall columns, the amount of material destabilised above the failure plane is larger than that of short columns. Therefore, the surface area of the mobilised mass that interacts with the surrounding fluid in tall columns is significantly higher than the short columns. This increase in the area of soil - fluid interaction results in an increase in the formation of turbulent vortices thereby altering the deposit morphology. It is observed that the vortices result in the formation of heaps that significantly affects the distribution of mass in the flow. In order to understand the behaviour of tall columns, the run-out behaviour of a dense granular column with an initial aspect ratio of 6 is studied. The collapse behaviour is analysed for different slope angles: 0°, 2.5°, 5° and 7.5°.

Investigation and dynamic analysis of the long runout catastrophic landslide at the Shenzhen landfill on December 20, 2015, in Guangdong, China

At 11:40 a.m., December 20, 2015, a catastrophic landslide occurred in Shenzhen, Guangdong, Southeast China. Seventy-seven people were killed, and 33 buildings were buried or damaged, which were in the direct path of the landslide at the Guangming New District. The landslide involved 2.73 million m3 of the municipal solid waste (MSW) and had a horizontal runout distance of 1100 m, over a vertical distance of 113 m, which was equivalent to a Fahrboschung of 6°, and covered an area of 0.38 km2. Basic post-failure characteristics are described in this study. Dynamic simulation software (DANW) and rheological models were used to simulate the runout behavior of the displaced landslide material, in order to provide information for the hazard zonation of similar types of potential MSW landslides. The simulated results revealed that a combination of the frictional model and Voellmy model is able to provide the best performance in simulating this landslide. Also, the results showed that this landslide had a duration of about 50 s, with a maximum velocity of 22.4 m/s. It was expected that these models and parameters could improve the accuracy of future hazard assessments of areas with geological, topographical, and climatic features similar to the Shenzhen Hong’ao landfill.

Initiation and Displacement Analysis of Cohesive Soil Slopes by Discrete Element Modelling

Kinematic and static analysis of geotechnical problems using the DEM has been widely accepted in the research arena for many years; however, its routine use in geotechnical practice for slope stability analysis still remains limited. This study focuses on the behavior of cohesive soil slopes undergoing failure initiation and succedent run-out. The numerical simulations of a supposititious slope composed of homogeneous cohesive soil were conducted using the DEM. The cohesive soil was simulated using contact-bonded graded aggregates of diameters ranging from 80 to 160 mm. This study investigated the microcrack-growth, particle displacements, particle movement and porosity changes within the slope fill. The simulation results showed that the failure mechanism is a rotational one at the failure initiation stage and gradually transfer to a slide/flow mode as progressive failure occurs. The porosity of deposit mass increased remarkably as result of dilation and block void. The run-out behavior of failure mass is not very sensitive with the viscous damping constant.

Subaqueous rock-avalanche deposits exposed by post-glacial isostatic rebound, Innfjorddalen, Western Norway

This paper presents a detailed description of deposits and landforms of multiple rock avalanches in Western Norway, one of which fell onto water-saturated sediments in Innfjorddalen below the former water level. Deposits of the latter are now exposed on the valley floor due to post-glacial isostatic rebound. At least three rock avalanches from the same source at Gråfonnfjellet Mountain have occurred during late glacial and post-glacial time, and their deposits are distributed over an area of 1.44km2 in the valley. These rock avalanches have volumes of 15.1×106m3, 5.4×106m3 and 0.3×106m3 and yielded cosmogenic radionuclide 10Be ages of 14.3±1.4ka, 8.79±0.94ka and 1.028±0.380ka, respectively. The youngest event dates, within uncertainty limits to a historic rock avalanche in the year 1611–12 CE. The rock avalanches formed a stratified succession of deposits. The rock-avalanche deposits (1.38m2) have lobate forms, have frontal rims and parallel ridges, extend across the valley floor and up the opposite slope, and form dams on the valley floor. Isolated hills comprised of rock boulders (0.61km2), interpreted to be ‘toma hills’, are disconnected from the main rock-avalanche deposits by a 520-m-wide zone of deformed, valley-fill sediments. Trenches and a ground penetrating radar survey of these deposits indicate large-scale deformation or liquefaction. Numerical runout modeling of the rock avalanches with the code DAN3D supports the interpretation of their landforms and sources, and highlights their runout behavior.

Investigation and dynamic analysis of a catastrophic rock avalanche on September 23, 1991, Zhaotong, China

At 6:10 p.m. on September 23, 1991, a catastrophic rock avalanche occurred in Zhaotong, Yunnan, southwestern China. Over 216 people were killed when the Touzhai village was overwhelmed directly in the path of the landslide. The landslide involved the failure of about 12 Mm3 of jointed basaltic rock mass from the source area. The displaced materials ran out a horizontal distance of 3650 m over a vertical distance of 960 m, equivalent to a Fahrboschung of 14.7°, and covered an area of 1.38 km2. To provide information for hazard zonation of similar type of potential landslides in the same area, we used a dynamic model (DAN-W) with three alternative rheological models to simulate the runout behaviour of the displaced landslide materials and found that a combination of the frictional model and Voellmy model could provide the best performance in simulating this landslide. The simulated results indicated that the duration of the movement is estimated at about 175 s for a mean velocity 21 m/s.

Observations of grain-scale interactions and simulation of dry granular flows in a large-scale flume

A series of 30 tests on dry granular flows were performed using a large-scale flume under varying source volumes and basal friction conditions to capture grain-scale interactions and their impact on overall runout behaviour. These grain interactions and ultimately the flow regimes developed were found to be a function of material source volume and boundary roughness. The dimensionless inertial number was computed for each flow, but was found to be of limited utility except perhaps to define a general state (e.g., liquid regime) for the material due to the high slip velocity encountered in the granular flows. Using the depth-averaged “dynamic analysis” numerical model DAN, it was found that a single set of semi-empirically derived frictional parameters (i.e., specific to internal and basal friction conditions) was appropriate for matching the overall mobility of the experimental flows over a range of flow volumes and slope inclinations. However, these angles were found to be lower than those determined from laboratory interface friction tests, highlighting the importance of collisional stress transfer in the basal zone of the dry flowing landslides.