Runout prediction of potential landslides based on the multi-source data collaboration analysis on historical cases

Long runout landslides involve a massive amount of energy and can be extremely hazardous owing to their long movement distance,high mobility and strong destructive power.Numerical methods have been widely used to predict the landslide runout but a fundamental problem remained is how to determine the reliable numerical parameters.This study proposes a framework to predict the runout of potential landslides through multi-source data collaboration and numerical analysis of historical landslide events.Specifically,for the historical landslide cases,the landslide-induced seismic signal,geophysical surveys,and possible in-situ drone/phone videos(multi-source data collaboration)can validate the numerical results in terms of landslide dynamics and deposit features and help calibrate the numerical(rheological)parameters.Subsequently,the calibrated numerical parameters can be used to numerically predict the runout of potential landslides in the region with a similar geological setting to the recorded events.Application of the runout prediction approach to the 2020 Jiashanying landslide in Guizhou,China gives reasonable results in comparison to the field observations.The numerical parameters are determined from the multi-source data collaboration analysis of a historical case in the region(2019 Shuicheng landslide).The proposed framework for landslide runout prediction can be of great utility for landslide risk assessment and disaster reduction in mountainous regions worldwide.

Mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradation

The mass-front velocities of granular flows results from the joint action of particle size gradations and the underlying surfaces.However,because of the complexity of friction during flow movement,details such as the slope-toe impedance effects and momentum-transfer mechanisms have not been completely explained by theoretical analyses,numerical simulations,or field investigations.To study the mass-front velocity of dry granular flows influenced by the angle of the slope to the runout plane and particle size gradations we conducted model experiments that recorded the motion of rapid and long-runout rockslides or avalanches.Flume tests were conducted using slope angles of 25°,35°,45°,and 55° and three particle size gradations.The resulting mass-front motions consisted of three stages:acceleration,velocity maintenance,and deceleration.The existing methods of velocity prediction could not explain the slowing effect of the slope toe or the momentum-transfer steady velocity stage.When the slope angle increased from 25° to 55°,the mass-front velocities dropped significantly to between 44.4% and59.6% of the peak velocities and energy lossesincreased from 69.1% to 83.7% of the initial,respectively.The velocity maintenance stages occurred after the slope-toe and mass-front velocity fluctuations.During this stage,travel distances increased as the angles increased,but the average velocity was greatest at 45°.At a slope angle of 45°,as the median particle size increased,energy loss around the slope toe decreased,the efficiency of momentum transfer increased,and the distance of the velocity maintenance stage increased.We presented an improved average velocity formula for granular flow and a geometrical model of the energy along the flow line.

Characteristics and Formation Mechanism of Giant Long-Runout Landslide: A Case Study of the Gamisi Ancient Landslide in the Upper Minjiang River, China

The upper reaches of the Minjiang River are in the eastern margin of the Tibetan Plateau,where active faults are well developed and earthquakes frequently occur.Anomalous climate change and the extremely complex geomechanical properties of rock and soil have resulted in a number of geohazards.Based on the analysis of remote sensing interpretations,geological field surveys,geophysical prospecting and geological dating results,this paper discusses the developmental characteristics of the Gamisi ancient landslide in Songpan County,Sichuan Province,and investigates its geological age and formation mechanism.This study finds that the Gamisi ancient landslide is in the periglacial region of the Minshan Mountain and formed approximately 25 ka BP.The landslide initiation zone has a collapse and slide zone of approximately 22.65×106–31.7×106 m3 and shows a maximum sliding distance of approximately 1.42 km,with an elevation difference of approximately 310 m between the back wall of the landslide and the leading edge of the accumulation area.The landslide movement was characterized by a high speed and long runout.During the sliding process,the landslide body eroded and dammed the ancient Minjiang River valley.The ancient river channel was buried 30-60 m below the surface of the landslide accumulation area.Geophysical prospecting and drilling observations revealed that the ancient riverbed was approximately 80-100 m thick.After the dam broke,the Minjiang River was migrated to the current channel at the leading edge of the landslide.The Gamisi ancient landslide was greatly affected by the regional crustal uplift,topography,geomorphology and paleoclimatic change.The combined action of periglacial karstification and climate change caused the limestone at the rear edge of the landslide fractured,thus providing a lithological foundation for landslide occurrence.Intense tectonic activity along the Minjiang Fault,which runs through the middle and trailing parts of the Gamisi ancient landslide,may have been the main factor inducing landsliding.Studying the Gamisi ancient landslide is of great significance for investigating the regional response to paleoclimatic change and geomorphologic evolution of the Minjiang Fault since the late Pleistocene and for disaster prevention and mitigation.

Modelling of the In uence of Tool Runout on Surface Generation in Micro Milling

Micro milling is a flexible and economical method to fabricate micro components with three-dimensional geometry features over a wide range of engineering materials. But the surface roughness and micro topography always limit the performance of the machined micro components. This paper presents a surface generation simulation in micro end milling considering both axial and radial tool runout. Firstly, a surface generation model is established based on the geometry of micro milling cutter. Secondly, the influence of the runout in axial and radial directions on the surface generation are investigated and the surface roughness prediction is realized. It is found that the axial runout has a significant influence on the surface topography generation. Furthermore, the influence of axial runout on the surface micro topography was studied quantitatively, and a critical axial runout is given for variable feed per tooth to generate specific surface topography. Finally, the proposed model is validated by means of experiments and a good correlation is obtained. The proposed surface generation model o ers a basis for designing and optimizing surface parameters of functional machined surfaces.

Changes in Runout Distances of Debris Flows over Time in the Wenchuan Earthquake Zone

A large number of debris flows occurred in the Wenchuan earthquake zone after the 12 May 2008 earthquake.The risks posed by these debris flows were rather high.An appropriate model is required to predict the possible runout distance and impacted area.This paper describes a study on the runout characteristics of the debris flows that occurred in the Wenchuan earthquake zone over the past four years.A total of 120 debris flows are analyzed.Separate multivariate regression models are established for the runout distances of hill-slope debris flows and channelized debris flows.The control variables include type of debris flow,debris flow volume,and elevation difference.Comparison of the debris flows occurring before and after the earthquake shows that the runout distance increased after the earthquake due to sufficient material supply and increased mobility of the source materials.In addition,the runout distances of annual debris flow events in 2008,2010 and 2011 are analyzed and compared.There is a tendency that the runout distance decreases over time due to the decreasing source material volume and possible changes of debris flow type.Comparison between the debris flows in the earthquake zone and the debris flows in Swiss Alps,Canada,Austria,and Japan shows that the former have a smaller mobility.

Hybrid Simulation of the Initiation and Runout Characteristics of a Catastrophic Debris Flow

On 13 August 2010, a catastrophic debris flow with a volume of 1.17 million m3 occurred in Xiaojiagou Ravine near Yingxiu town of Wenchuan county in Sichuan Province, China. The main source material was the landslide deposits retained in the ravine during the 2008 Wenchuan earthquake. This paper describes a two-dimensional hybrid numerical method that simulates the entire process of the debris flow from initiation to transportation and finally to deposition. The study area is discretized into a grid of square zones. A two dimensional finite difference method is then applied to simulate the rainfall-runoff and debris flow runout processes. The analysis is divided into three steps; namely, rainfall-runoff simulation, mixing water and solid materials, and debris flow runout simulation. The rainfall-runoff simulation is firstly conducted to obtain the cumulative runoff near the location of main source material and at the outlet of the first branch. The water and solid materials are then mixed to create an inflow hydrograph for the debris flow runout simulation. The occurrence time and volume of the debris flow can be estimated in this step. Finally the runout process of the debris flow is simulated. When the yield stress is high, it controls the deposition zone. When the yield stress is medium or low, both yield stress and viscosity influence the deposition zone. The flow velocity is largely influenced by the viscosity. The estimated yield stress by the equation, ty = pghsinO, and the estimated viscosity by the equation established by Bisantino et al. （2010） provide good estimates of the area of the debris flow fan and the distribution of deposition depth.

Characteristics of grain size distribution and the shear strength analysis of Chenjiaba long runout coseismic landslide

Study on the grain size distribution characteristics and the frictional strength behavior of the slide deposits are helpful to disclose the landslide runout process and understand the mechanism of a long runout landslide. We performed grain size distribution analysis on samples collected from Chenjiaba landslide induced by Wenchuan earthquake. The grain size distribution of samples from the landslide sections quantitatively depicts a gradual coarsening upward grading from shear zone to the top section. Then a multistage-multiphase ring shearing approach was used to determine a comparative shear strength behavior of samples from each landslide section. In this method, a sample was sheared continuously for large displacement and fast rate on different normal stress conditions. The multiphase shear mode with a maximum of 105 mm/min rate has allowed observing the qualitative change and patterns of the frictional resistance behaviors of soils under different normal stresses. The results of coefficient of friction values under multiphase shear mode have shown substantial post peak shear weakening behaviors after large shear displacement that can be narrated with long runout processes. The shear strength test results indicate that the shear zone samples have developed higher friction angle values compared to overlying section samples, on the last phase of shear process, which may be very important to understand the braking mechanism of a long runout landslide.

New Mathematical Method for the Determination of Cutter Runout Parameters in Flat-end Milling

The cutting force prediction is essential to optimize the process parameters of machining such as feed rate optimization, etc. Due to the significant influences of the runout effect on cutting force variation in milling process, it is necessary to incorporate the cutter runout parameters into the prediction model of cutting forces. However, the determination of cutter runout parameters is still a challenge task until now. In this paper, cutting process geometry models, such as uncut chip thickness and pitch angle, are established based on the true trajectory of the cutting edge considering the cutter runout effect. A new algorithm is then presented to compute the cutter runout parameters for flat-end mill utilizing the sampled data of cutting forces and derived process geometry parameters. Further, three-axis and five-axis milling experiments were conducted on a machining centre, and resulting cutting forces were sampled by a three-component dynamometer. After computing the corresponding cutter runout parameters, cutter forces are simulated embracing the cutter runout parameters obtained from the proposed algorithm. The predicted cutting forces show good agreements with the sampled data both in magnitude and shape, which validates the feasibility and effectivity of the proposed new algorithm of determining cutter runout parameters and the new way to accurately predict cutting forces. The proposed method for computing the cutter runout parameters provides the significant references for the cutting force prediction in the cutting process.

Application of Cooling Water in Controlled Runout Table Cooling on Hot Strip Mill

The controlled runout table cooling is essential in determining the final mechanical properties and flatness of steel strip.The heat of a hot steel strip is mainly extracted by cooling water during runout.In order to study the heat transfer by water jet impingement boiling during runout,apilot facility was constructed at the University of British Columbia.On this pilot facility,the water jet impingement tests were carried out under various cooling conditions to investigate the effect of processing parameters,such as cooling water temperature,water jet impingement velocity,initial strip temperature,water flow rate,water nozzle diameter and array of water nozzles,on the heat transfer of heated strip.The results obtained contribute to the optimization of cooling water during runout.

Long runout mechanism of the Shenzhen 2015 landslide:insights from a two-phase flow viewpoint

A catastrophic landslide occurred at Hongao dumpsite in Guangming New District of Shenzhen, South China, on December 20, 2015. An estimated total volume of 2.73×106 m3 of construction spoils was mobilized during this event. The landslide traveled a long distance on a low-relief terrain. The affected area was approximately 1100 m in length and 630 m in width. This landslide made 33 buildings destroyed, 73 people died and 4 people lost. Due to the special dumping history and other factors, soil in this landfill is of high initial water content. To identify the major factors that attribute to the long runout character, a two-phase flow model of Iverson and George was used to simulate the dynamics of this landslide. The influence of initial hydraulic permeability, initial dilatancy, and earth pressure coefficient was examined through numerical simulations. We found that pore pressure has the most significant effect on the dynamic characteristics of Shenzhen landslides. Average pore pressure ratio ofthe whole basal surface was used to evaluate the degree of liquefaction for the sliding material. The evolution and influence factors of this ratio were analyzed based on the computational results. An exponential function was proposed to fit the evolution curve of the average pore pressure ratio, which can be used as a reasonable and simplified evaluation of the pore pressure. This fitting function can be utilized to improve the single-phase flow model.

Landslide initiation and runout susceptibility modeling in the context of hill cutting and rapid urbanization: a combined approach of weights of evidence and spatial multicriteria

Rainfall induced landslides are a common threat to the communities living on dangerous hillslopes in Chittagong Metropolitan Area, Bangladesh. Extreme population pressure, indiscriminate hill cutting, increased precipitation events due to global warming and associated unplanned urbanization in the hills are exaggerating landslide events. The aim of this article is to prepare a scientifically accurate landslide susceptibility map by combining landslide initiation and runout maps. Land cover, slope, soil permeability, surface geology, precipitation, aspect, and distance to hill cut, road cut, drainage and stream network factor maps were selected by conditional independence test. The locations of 56 landslides were collected by field surveying. A weight of evidence(Wo E) method was applied to calculate the positive(presence of landslides) and negative(absence of landslides) factor weights. A combination of analytical hierarchical process(AHP) and fuzzymembership standardization(weighs from 0 to 1) was applied for performing a spatial multi-criteria evaluation. Expert opinion guided the decision rule for AHP. The Flow-R tool that allows modeling landslide runout from the initiation sources was applied. The flow direction was calculated using the modified Holmgren's algorithm. The AHP landslide initiation and runout susceptibility maps were used to prepare a combined landslide susceptibility map. The relative operating characteristic curve was used for model validation purpose. The accuracy of Wo E, AHP, and combined susceptibility map was calculated 96%, 97%, and 98%, respectively.

Analysis of Impact of Disc Lateral Runout on Brake Drag

Brake drag is the main factor affecting the transmission efficiency and vehicle fuel consumption. This paper focused on analyzing the impact of assembled disc lateral runout on brake drag. First the impact mechanism of lateral disc runout on drag was analyzed theoretically. Then the brake drag torque under different assembled disc lateral runout was tested to figure out the relationship between them. And then, the influence factors on disc lateral runout were analyzed and the disc lateral runout was optimized. Finally, the vehicle resistance of the original car and the prototype with optimized brake were compared. The result shows that the vehicle resistance after optimized is reduced by 3%.

基于离散元Runout预测的张家湾滑坡风险评估

滑坡是我国最重要的地质灾害之一,其每年造成大量的人员伤亡和财产损失,故滑坡风险评估对防治滑坡灾害、降低社会经济损失具有重要意义。基于现场野外调查,利用离散元软件UDEC对西宁市张家湾滑坡进行Runout预测分析,结合动力分析与条件分析法对张家湾滑坡进行风险评估。结果表明:张家湾滑坡在天然工况下为稳定状态,在暴雨工况下为欠稳定状态,其最远移距为55m,最大影响范围为1.106×105 m2;张家湾滑坡在暴雨工况下的失稳概率为0.459;张家湾滑坡一旦在暴雨情况下发生失稳,人员伤亡风险值为46人,根据滑坡灾害社会接受水平曲线判定其属于不可接受范围;经济损失风险值为5180.88万元。根据经济损失风险等级进行判断其属于第5等级。

An AI‑Based Method for Estimating the Potential Runout Distance of Post‑Seismic Debris Flows

The widely distributed sediments following an earthquake presents a continuous threat to local residential areas and infrastructure.These materials become more easily mobilized due to reduced rainfall thresholds.Before establishing an efective management plan for debris fow hazards,it is crucial to determine the potential reach of these sediments.In this study,a deep learning-based method-Dual Attention Network(DAN)-was developed to predict the runout distance of potential debris fows after the 2022 Luding Earthquake,taking into account the topography and precipitation conditions.Given that the availability of reliable precipitation data remains a challenge,attributable to the scarcity of rain gauge stations and the relatively coarse resolution of satellite-based observations,our approach involved three key steps.First,we employed the DAN model to refne the Global Precipitation Measurement(GPM)data,enhancing its spatial and temporal resolution.This refnement was achieved by leveraging the correlation between precipitation and regional environment factors(REVs)at a seasonal scale.Second,the downscaled GPM underwent calibration using observations from rain gauge stations.Third,mean absolute error(MAE),mean square error(MSE),and root mean square error(RMSE)were employed to evaluate the performance of both the downscaling and calibration processes.Then the calibrated precipitation,catchment area,channel length,average channel gradient,and sediment volume were selected to develop a prediction model based on debris fows following the Wenchuan Earthquake.This model was applied to estimate the runout distance of potential debris fows after the Luding Earthquake.The results show that:(1)The calibrated GPM achieves an average MAE of 1.56 mm,surpassing the MAEs of original GPM(4.25 mm)and downscaled GPM(3.83 mm);(2)The developed prediction model reduces the prediction error by 40 m in comparison to an empirical equation;(3)The potential runout distance of debris fows after the Luding Earthquake reaches 0.77 km when intraday rainfall is 100 mm,while the minimum distance value is only 0.06 km.Overall,the developed model ofers a scientifc support for decision makers in taking reasonable measurements for loss reduction caused by post-seismic debris fows.

高位远程地质灾害研究:回顾与展望

在全球范围内,高位远程地质灾害造成了多起群死群伤事件和特大经济损失,是特大型地质灾害防灾减灾科技攻关的难点。文章系统回顾了高位远程地质灾害的研究历程,认为常规的“高速远程滑坡”研究难以适应高山、极高山区复合型地质灾害防灾减灾的要求,提出了从高位失稳、远程成灾和风险防控全链条的高位远程地质灾害研究思路,探讨了高位崩滑启动源区的易灾地质结构特征和早期识别技术、高速碎屑流远程链动机理和边界层效应以及风险评估和防灾减灾问题。通过对青藏高原高山、极高山区的高位远程地质灾害研究,揭示了高位滑坡碎屑流势流体链动传递机理,以及紊流体和犁切体的边界层效应,提出可以通过改造高势能碎屑流体的边界层底坡、增大湍流边界层内湍动能的生成与组合障桩前死区范围的消能降险方法。最后,针对铁路、公路、水电工程、边疆城镇和国防建设的发展,讨论了复合型高位远程滑坡灾害的防灾减灾将面临的新挑战,提出了易灾地质结构孕灾机理、高位远程链灾动力过程和风险防控理论与技术等3方面亟待加强的研究方向。

Numerical Simulation of Rainfall-induced Xianchi Reservoir Landslide in Yunyang,Chongqing,China

A calamitous landslide happened at 22:00 on September 1,2014 in the Yunyang area of Chongqing City,southwest China,enforcing the evacuation of 508 people and damaging 23 buildings.The landslide volume comprised 1.44 million m^(3) of material in the source area and 0.4 million m^(3) of shoveled material.The debris flow runout extended 400 m vertically and 1600 m horizontally.The Xianchi reservoir landslide event has been investigated as follows:(1)samples collected from the main body of landslide were carried out using GCTS ring shear apparatus;(2)the parameters of shear and pore water pressure have been measured;and(3)the post-failure characteristics of landslide have been analyzed using the numerical simulation method.The excess pore-water pressure and erosion in the motion path are considered to be the key reasons for the long-runout motion and the scale-up of landslides,such as that at Xianchi,were caused by the heavy rainfall.The aim of this paper is to acquired numerical parameters and the basic resistance model,which is beneficial to improve simulation accuracy for hazard assessment for similar to potentially dangerous hillslopes in China and elsewhere.

白龙江流域大型高位滑坡成灾动力过程模拟研究

白龙江流域山高坡陡,分布大量高位滑坡,是我国高位地质灾害风险极高的地区。舟曲县立节镇北山古滑坡位于白龙江左岸,滑坡剪出口与江面高差约700 m,历史上曾发生过多次变形破坏。通过资料搜集、遥感调查与解译、现场调查等手段,查明了立节北山滑坡的地质环境与变形破坏特征,基于光滑质点流体动力学与等效流体模型,开展滑坡后破坏运动过程模拟,对远程致灾危险进行预测分析。模拟分析表明,立节北山滑坡若发生失稳剧滑,将形成高位高速远程滑坡-碎屑流灾害,滑动距离达1 600 m,最大运动速度45.7 m/s,沿途铲刮方量77.7万m~3,滑体扩容系数1.32。滑体约200 s后完全停止运动并堆积,堆积区面积2.2×10~5 m~2,覆盖坡脚立节镇一半的范围,最大堆积厚度17.8 m,最大冲击速度30 m/s。研究结果为立节北山滑坡开展风险评价与分区提供定量化数据,为白龙江流域大型高位滑坡精细调查与风险评估提供参考依据。

基于Simulink轮胎跳动对重型车转向特性影响分析

转向过程轮胎受地面载荷影响呈现跳动,而其对车辆稳定转向产生重要影响。车辆与地面间的接触是通过轮胎得以实现,轮胎受力直接影响到车辆转向稳定性。选用重型车辆轮胎外倾时的受力进行分析,基于此,对空载和满载工况下,高低速转向时的转角偏差进行分析;并对空载和满载工况下,转向时,车轮的摆动误差及滑移量进行分析,获取不同工况下各参数最优的数学模型;根据数学模型分析,基于Simulink搭建包含承载特性的转向系统模型,以此分析不同转速条件下轮胎的受力和轮胎跳动对转向的影响;应用实际车辆,选取双移线转向工况,对比分析运行轨迹和转角关系的差异,以此验证数学模型和仿真分析的可靠性。结果可知:在转向过程中,各轮胎的侧向力变化趋势基本一致;随着车速的增加,在转向过程中各轮胎所受的侧向力也呈现增加的趋势;随着速度的增加,前轴内侧轮胎受力先减小后增加;满载时,车轮跳动对车轮摆动误差的影响随着车轮转角增大而增大,而空载时,则影响更大,变化趋势也更复杂;实车测试与仿真轨迹基本保持一致,且外侧轮转向角曲线基本无较大变化,保持一致特性,误差小于3%,表明数学模型和仿真分析的准确性,为此类设计提供参考。

Progressive fragmentation of granular assemblies within rockslides: Insights from discrete-continuous numerical modeling

Rock fragmentation plays a critical role in rock avalanches,yet conventional approaches such as classical granular flow models or the bonded particle model have limitations in accurately characterizing the progressive disintegration and kinematics of multi-deformable rock blocks during rockslides.The present study proposes a discrete-continuous numerical model,based on a cohesive zone model,to explicitly incorporate the progressive fragmentation and intricate interparticle interactions inherent in rockslides.Breakable rock granular assemblies are released along an inclined plane and flow onto a horizontal plane.The numerical scenarios are established to incorporate variations in slope angle,initial height,friction coefficient,and particle number.The evolutions of fragmentation,kinematic,runout and depositional characteristics are quantitatively analyzed and compared with experimental and field data.A positive linear relationship between the equivalent friction coefficient and the apparent friction coefficient is identified.In general,the granular mass predominantly exhibits characteristics of a dense granular flow,with the Savage number exhibiting a decreasing trend as the volume of mass increases.The process of particle breakage gradually occurs in a bottom-up manner,leading to a significant increase in the angular velocities of the rock blocks with increasing depth.The simulation results reproduce the field observations of inverse grading and source stratigraphy preservation in the deposit.We propose a disintegration index that incorporates factors such as drop height,rock mass volume,and rock strength.Our findings demonstrate a consistent linear relationship between this index and the fragmentation degree in all tested scenarios.

大型曲轴圆角滚压矫直工艺优化研究

长度为1.6~8 m的大型曲轴在制造加工过程中,由于热变形和冷却不均等原因会造成二次弯曲,需要通过圆角滚压矫直工艺进一步改善主轴颈和连杆颈中心的跳动量。为了解决大型曲轴跳动量超差现象并提高加工效率,旨在以16V型大型曲轴为研究对象,基于已有结论和建立优化数学模型,运用NSGA-Ⅲ算法和PlatEMO平台对圆角滚压矫直工艺实行了多目标优化,并结合TOPSIS决策方法计算了Pareto解集的贴近度指数,根据指数排序结果进一步选择每次滚压矫直的最佳方案,实现了工艺参数(滚压力、滚压角度范围)的优化。优化结果与有限元仿真结果具有较高的一致性,有效降低了16V型大型曲轴各主轴颈的矫后跳动量和减少了滚压矫直的次数,确保曲轴性能达到要求。