Landslide Dam Failure Research Articles

Analysis of the microseismicity characteristics in landslide dam failure flume tests: implications for early warning and dynamics inversion

Analysis of the microseismicity characteristics in landslide dam failure flume tests: implications for early warning and dynamics inversion

Emergency rescue and disposal technology for Baige Barrier Lake on the Jinsha River, China

<p indent="0mm">When a landslide blocks the river and forms a barrier lake, the need for emergency rescue is urgent, the environment is hazardous, environmental conditions are harsh, transportation is inconvenient, and disposal is difficult. Once the lake is out of control and released, it will endanger people’s lives, property, and the safety of cascade hydropower stations safety downstream. Based on the analysis of the characteristics and causes of “10·11” and “11·03” Baige barrier lakes in the upper reach of Jinsha River, a hyperbolic dam erosion model is used to predict the peak discharge of the two Baige barrier lakes to be 10000 and <sc>44370 m³/s,</sc> respectively, to investigate emergency disposal technology and explain the process of landslide dam failure and rescue. Therefore, it is proposed that the emergency disposal of the “11·03” barrier lake should be a series of emergency measures for manual excavation of drainage channel, destruction of the cofferdam for the Suwalong Station under construction, and discharge of the reservoir of Liyuan Station in operation. The results show that for the “11·03” barrier lake, (1) the excavation of the 13.5-m deep drainage channel reduced the peak discharge to <sc>33900 m³/s,</sc> which is the same as the predicted <sc>34400 m³/s;</sc> (2) the destruction of the cofferdam for the Suwalong Station under construction avoids superimposition and magnification of the flood peak, and if the cofferdam is not destructed, the peak discharge may be increased from 19800 to <sc>32200 m³/s;</sc> (3) the water discharge of the Liyuan reservoir successfully reduced the peak discharge from 7190 to <sc>4500 m³/s,</sc> reducing the flood control pressure of downstream cascade stations and minimizing the coastal disaster loss through the joint dispatch of the cascade reservoirs. This study provides a systematic back analysis of the rescue process and key technologies and emergency measures of the Baige barrier lakes and a reference for the emergency rescue of similar landslide dams and the risk prevention and control of cascade hydropower stations in the basin.

Amplification effect of cascading breach discharge of landslide dams

Affected by earthquakes and heavy rainfall, multiple landslide dams often cluster closely together along river reaches or gullies. Compared with a single landslide dam, the burst flood produced by the cascading failure of multiple landslide dams can be enhanced, seriously threatening life and property downstream. Here, we conduct a series of experiments in a 42 m flume to investigate the failure mechanisms of single and paired dams with fine-grained, well-graded, and coarse-grained debris; analyze the effects of dam geometry and initial water level of a downstream dam on the cascading breach; and quantitatively evaluate the amplification effect of cascading breach discharge. Single dams fail by overtopping along with seepage instability for a fine-grained dam, headcutting for a well-graded dam, and overtopping for a coarse-grained dam, respectively. The type of failure which occurs for a single dam is influenced by the shear strength of the dam material and seepage. However, the downstream dams in cascading tests fail by overtopping irrespective of dam material due to the large outburst floods from the upstream dams. A general flat slope angle is maintained during breaching for the fine-grained and coarse-grained dams, while a step-pool structure is developed for the well-graded dams because the finer grains are easier to wash away than coarse grains. The peak breach discharge for a downstream dam is 1.4–1.9 times the value for an upstream dam in the experimental runs, indicating the amplification effect of breach discharge. The amplification effect has a negative linear correlation with the time interval between the peak breach discharges of the two dams because the overlap of breach processes of upstream and downstream dams is gradually reduced as the time interval increases.

Seismic Characterization of a Landslide Dam Failure Hazard Chain: Insights into Flow Dynamics and Implications for Early Warning

Seismic Characterization of a Landslide Dam Failure Hazard Chain: Insights into Flow Dynamics and Implications for Early Warning

Influences of Spillway Section Morphologies on Landslide Dam Breaching

Spillway excavation is often adopted as a precautionary engineering measure for disaster mitigation before landslide dam breaching. Based on the landslide dam breach mechanisms, this paper focuses on developing a numerical model to comprehensively discuss the issue based on three documented landslide dam failures, such as Tangjiashan, Xiaogangjian, and Baige landslide dams. The spillway cross section morphologies were modeled with different sizes under common shape (i.e., an inverted trapezoid) and slope conditions. The influence of cross section on dam breach processes was analyzed under conditions of different depth, bottom width, slope ratio in the cross and longitudinal sections, with/without spillway. The following conclusions can be drawn: 1) excavation of a spillway can effectively reduce the peak breach flow, therefore delay the time to peak; 2) the peak breach flow dramatically decreases and the time to peak delays as the spillway depth increases; 3) the peak breach flow changes little and the time to peak occurs earlier with the increment in spillway bottom width; 4) the peak breach flow decreases and the time to peak delays with the decrease of slope ratio in cross section in the spillway; 5) the slope ratio in the longitudinal section has little influence on the breach process. Hence, if conditions permit, the spillway with large spillway depth, small bottom width, and gentle slope ratio in the cross section is the preferable section morphology for the emergency disposal of the landslide dam.

Flow amplification from cascading landslide dam failures: Insights from flume experiments

The 2008 Wenchuan Earthquake triggered numerous co-seismic landslides, and formed many landslide dams. Debris flows or floods during intense rainfall can cause the sequential collapse of those landslide dams. There is an amplification effect of the cascading landslide dam failures, which increases the magnitudes of debris flows or floods. Runs of flume experiments with different initial conditions were conducted to study the scale amplification effect. Among them, a large-scale flume experiment was performed to reduce the size effect of the miniaturized physical experiments to some extent. Experimental data such as the flow discharge, pore pressures, and microseismic and acoustic signals were used to investigate the dam failure processes and to quantify the amplification scale. The experimental results show that channel gradients and dam-failure patterns have significantly influences on the amplification effect. The intrinsic mechanism of the amplification effect can be interpreted from the perspective of energy, which is a progressive storage of potential energy and subsequent rapid release of the energy. Steep channel gradients imply greater potential energy and lower stability of the landslide dam. The sudden dam collapse related to internal pore pressure evolution will lead to rapid release of the accumulated potential energy to downstream, and cause a maximum instantaneous dam-break discharge. Experimental results show that the peak dam-break discharge caused by sudden failure can be 2–3 times that of overtopping, which should be fully considered to avoid underestimating the scale of the potential catastrophe.

Process Analysis and Prediction of a Multi-stage Landslide Dam Failure

The studies of mechanism and calculated model of the earth-fill dam and landslide dam have a significant impact on the prediction and risk assessment for dam failure. The present study selected the event of a multi-stage landslide dam failure in southwestern China as a case study. Based on a mathematic model that can consider the failure mechanism, the key parameter can be obtained by back analysis, the twice failure processes can be displayed as well. It indicates that the second landslide dam cannot break under natural conditions, i.e. the landslide dam failure needs manual intervention, which is consistent with the actual situation. Because the landslide would occur again in different cumulated volumes in the future, the dam failure is predicted using the same model. The result illustrates that the maximal flow comes up to 20,000-60,000 m3/s after the dam failure and the failure would occur in a short day. The analysis and prediction provide an improved insight into the landslide dam failure process and risk control.

The formation and geometry characteristics of boulder bars due to outburst floods triggered by overtopped landslide dam failure

Abstract. Boulder bars are a common form of riverbed morphology that could be affected by landslide dams. However, few studies have focused on the formation and geometry characteristics of boulder bars due to outburst floods triggered by landslide dam failure. In such a way, eight group landslide dam failure experiments with a movable bed length of 4 to 7 times the dam length with 25 boulder bars were carried out. In addition, 38 boulder bars formed in the field triggered by four landslide dam failures were investigated. The aim of this paper is to study the formation and geometry characteristics of boulder bars along the riverbeds. The results show that boulder bars are formed after peak discharge of outburst flow. The number of boulder bars is 0.4 to 1.0 times the ratio of riverbed length to dam bottom length. Besides, boulder bars have the characteristic of lengthening upstream during the failure process. A boulder bar's upstream edge has a more extensive development than a boulder bar's downstream edge. The length of a boulder bar along the channel changes faster than the boulder bar's width and height. After the dam failure, the boulder bar's length is about 8 to 14 times its width. The relationship between the ratio of boulder bar length to width and the boulder bar's dimensionless length could be described with a hyperbolic equation. The dimensionless area of the boulder bar increases linearly with the dimensionless area of the river section, and the linear ratio is about 0.5. With the field data, this demonstrates that the formation and geometry characteristics of boulder bars in tests are consistent with the field boulder bars. Therefore, the results in this paper are credible and can be applied to the riverbed's geomorphological characteristics analysis triggered by overtopped landslide dam failure. The plentiful experimental and field data could contribute to the community boulder bar research.

Uncertainty quantification in shallow water-sediment flows: A stochastic Galerkin shallow water hydro-sediment-morphodynamic model

All shallow water hydro-sediment-morphodynamic (SHSM) models are prone to uncertainty arising from inadequate representation of the underlying physics and error in input parameters. At the time of writing, most SHSM models solve deterministic problems, whilst studies of uncertainty quantification in SHSM models remain rare. Here a new stochastic SHSM model is proposed, extended from a well-balanced, operator-splitting-based, generalized polynomial chaos stochastic Galerkin (gPC-SG) solver of the one-dimensional shallow water hydrodynamic equations. A series of probabilistic numerical tests are carried out, corresponding to idealized dam break flow over a fixed bed and laboratory experiments of flow-sediment-bed evolutions induced by a sudden dam break and by landslide dam failure. The proposed modelling framework shows promise for uncertainty quantification of shallow water-sediment flows over erodible beds.

Numerical simulation of landslide dam overtopping failure considering headward erosion

Landslide dams often fail shortly after the formation, resulting in huge risks to the downstream residents and properties. Fast and accurate forecasting of the breaching process and discharge hydrograph is important for a decision making to mitigate the damages. Morphological data indicate that the longitudinal length of most landslide dams is much larger than their transverse length. Additionally, headward erosion is more intense in landslide dams than manmade dams during the overtopping failure process. However, most existing models neglect this phenomenon. The objective of this study is to build up a dam-break model considering the headward erosion process, assuming that the change rate of downstream slope-angle is consistent with the rate of breach vertical erosion. And a dam-break numerical model to simulate the overtopping failure process of landslide dams considering the headward erosion was developed based on the theories of hydraulics, hydrology, soil mechanics, sediment dynamics, and etc. Nevertheless, the breach final bottom elevation, which can only be measured after the dam failure, is directly applied in currently available dam break models. To overcome this problem and for the prediction purpose of a newly formed landslide dam, we proposed an empirical model to estimate the breach final bottom elevations of high, medium and low erodibility landslide dams based on the statistical analysis of worldwide landslide dam failure cases collected recently. To verify the effectiveness of proposed dam-break numerical model, the ‘11.03′ Baige landslide dam which locates at the border of Tibet Autonomous Region and Sichuan province was selected as a case study. Results of this study show that the relative errors in the simulated peak discharge, time to the peak, and the total flood volume are 1.59%, 3.50% and 0.53%, respectively, which meet the accuracy requirements of hydrological forecasting. The relative error in the prediction of breach final bottom elevation is 4.28%, which indicates that the accuracy of the simulation is satisfactory. Finally, a sensitivity analysis indicates that the downstream slope affects the prediction of the breach and flood hydrograph significantly, and the excavation of diversion channel is an effective measure to reduce the peak discharge of dam overtopping failure.

Risk-Based Warning Decision Making of Cascade Breaching of the Tangjiashan Landslide Dam and Two Smaller Downstream Landslide Dams

Mega earthquakes or serious rainfall storms often cause crowded landslides in mountainous areas. A large part of these landslides are very likely blocking rivers and forming landslide dams in series along rivers. The risks of cascading failure of landslide dams are significantly different from that of a single dam. This paper presented the work on risk-based warning decision making on cascading breaching of the 2008 Tangjiashan landslide dam and two small downstream landslide dams in a series along Tongkou River. The optimal decision was made by achieving minimal expected total loss. Cascade breaching of a series of landslide dams is more likely to produce a multi-peak flood. When the coming of the breaching flood from the upstream dam perfectly overlaps with the dam breaching flood of the downstream dam, a higher overlapped peak flood would occur. When overlapped peak flood occurs, the flood risk would be larger and evacuation warning needs to be issued earlier to avoid serious life loss and flood damages. When multi-peak flood occurs, people may be misled by the warning of the previous peak flood and suddenly attacked by the peak flood thereafter, incurring catastrophic loss. Systematical decision making needs to be conducted to sufficiently concern the risk caused by each peak of the breaching flood. The dam failure probabilityPflinearly influences the expected life loss and flood damage but does not influence the evacuation cost. The expected total loss significantly decreases withPfwhen the warning time was insufficient. However, it would not change much withPfwhen warning time is sufficient.

Experimental study on the longitudinal evolution of the overtopping breaching of noncohesive landslide dams

The failure of landslide dams is a sudden geological disaster, and thus their formation and failure greatly threaten the security of people's lives and property. In this research, the influences of different flume gradients, dam heights, and downstream slope angles relative to the flume bed on the overtopping breaching process of noncohesive landslide dams are explored through 12 sets of model experiments. Based on these experimental results, the dam overtopping breaching can be divided into four stages: initiation, head cutting, acceleration, and riverbed rebalancing. The variation in the erosion rate ( E AX and E BX ) and the downstream slope angle relative to the horizontal line ( Φ ) exhibit clear differences in the different stages. The influences of the flume gradient, dam height, and downstream slope angle on the breaching process of landslide dams are different. In our experiments, accumulation bodies could only form in the middle and lower parts of the downstream dam face when the total height from the spillway to the flume bed was greater than 15 cm. In addition, the downstream slope angle relative to the horizontal line determined the breaching process and stage of the dam overtopping breaching. Since the dam breach evolution mode and dam overtopping breaching process were mainly affected by the dam height and downstream slope angle relative to the horizontal line, the evolution of the longitudinal section in the process of dam body failure can be divided into four modes based on our experimental results. The applicability of the widely used empirical equations for the erosion rate was assessed using the experimental data, which revealed obvious differences between the measured and calculated erosion rates. However, the erosion rate and the shear stress at the soil/water interface exhibited a good correlation in every test. Therefore, these widely used empirical equations need to be improved in future research. This preliminary research provides a basis for subsequent studies of dam breaching using models and a scientific reference for the prevention and mitigation of landslide dams. • Twelve experimental tests were designed to reproduce the breaching process of landslide dams. • The influences of the flume gradient, dam height, and downstream slope angle on the dam breaching process are different. • The breaching process of landslide dams can be divided into four stages. • The longitudinal evolution of dam breaching was classified into four modes according to three critical values.

Seismic signal characteristics and interpretation of the 2020 “6.17” Danba landslide dam failure hazard chain process

Landslide dam failures have devastating capability to cause significant hazards to human lives and infrastructure along their flooding paths. Recent studies have explored such hazards based on environmental seismology to analyze the process of evolution using the time-frequency characteristics of seismic signals. However, most research has focused on reconstructing individual processes (e.g., debris flows, landslides, and floods). Previous studies on a comprehensive analysis of the entire hazard chain process have been limited. Challenges lie in the integration of seismic signals with different energy levels during different hazard stages. To address this issue, post-hazard surveys, remote sensing, and seismic signals were obtained in this study to comprehensively analyze the evolution process of the Danba landslide dam failure hazard chain of June 17, 2020, in China. We developed weak-signal processing using a band-pass filter, empirical mode decomposition, fast Fourier transform, and short-time Fourier transform to process and analyze the seismic data and accurately extract the signals for the debris flow, landslide, flood, and noise attenuation in the hazard chain. The evolution process of each stage in the hazard chain was then interpreted. The debris flow, landslide, barrier lake bursting, and flood routing were analyzed to determine their evolution modes. In addition, the reactivation of ancient landslides downstream caused by flood erosion was also identified, with stage explanations. This method provides new ideas for interpreting the hazard chain processes and evolution modes of landslide dam failure hazard chains and theoretical guidance for future hazard early warning and mitigation.

Modeling Flood Peak Discharge Caused by Overtopping Failure of a Landslide Dam

Overtopping failure often occurs in landslide dams, resulting in the formation of strong destructive floods. As an important hydraulic parameter to describe floods, the peak discharge often determines the downstream disaster degree. Based on 67 groups of landslide dam overtopping failure cases all over the world, this paper constructs the calculation model for peak discharge of landslide dam failure. The model considers the influence of dam erodibility, breach shape, dam shape and reservoir capacity on the peak discharge. Finally, the model is compared with the existing models. The results show that the new model has a higher accuracy than the existing models and the simulation accuracy of the two outburst peak discharges of Baige dammed lake in Jinsha River (10 October 2018 and 3 November 2018) is higher (the relative error is 0.73% and 6.68%, respectively), because the model in this study considers more parameters (the breach shape, the landslide dam erodibility) than the existing models. The research results can provide an important reference for formulating accurate and effective disaster prevention and mitigation measures for such disasters.

Amplification of flood discharge caused by the cascading failure of landslide dams

The cascading failure of multiple landslide dams can trigger a larger peak flood discharge than that caused by a single dam failure. Therefore, for an accurate numerical simulation, it is essential to elucidate the primary factors affecting the peak discharge of the flood caused by a cascading failure, which is the purpose of the current study. First, flume experiments were done on the cascading failure of two landslide dams under different upstream dam heights, downstream dam heights, and initial downstream reservoir water volumes. Then, the experimental results were reproduced using a numerical simulation model representing landslide dam erosion resulting from overtopping flow. Finally, the factors influencing the peak flood discharge caused by the cascading failure were analyzed using the numerical simulation model. Experimental results indicated that the inflow discharge into the downstream dam at the time when the downstream dam height began to rapidly erode was the main factor responsible for a cascading failure generating a larger peak flood discharge than that generated by a single dam failure. Furthermore, the results of a sensitivity analysis suggested that the upstream and downstream dam heights, initial water volume in the reservoir of the downstream dam, upstream and downstream dam crest lengths, and distance between two dams were among the most important factors in predicting the flood discharge caused by the cascading failure of multiple landslide dams.

Numerical investigation of flash flood dynamics due to cascading failures of natural landslide dams

A series of natural landslide dams commonly form in a river valley in mountainous areas. Their failures are frequently triggered by intense rainfall, which may result in severe flash flooding or debris flow in a short period. It is important for risk mitigation to develop greater evidence-based understanding of flood dynamics due to cascading dam failures. Based on detailed hydro-morphodynamic modeling of various scenarios, this study systematically evaluates the formation and evolution of flash floods due to a cascading failure of natural landslide dams. The hydro-morphodynamic model has been shown to be capable of simulating shock-captured flows and resultant morphological changes. In this study, we first calibrate the dynamic model with dedicated experimental data, and then apply it to simulate a variety of designed flash flood scenarios caused by cascading dam failures. Moreover, process-based flood dynamics and their evolution are explored in detail. Results indicate that cascading dam failures in a sloping channel cause an overall amplification of flash flood dynamics in the flow direction, but fluctuation of key hydraulic parameters occurs around each dam. Also, bigger landslide dams prevent upstream flood propagation better, but the blockage of the flows raises the potential flow energy. This implies a higher potential hazard risk in case of ‘sudden-onset’ failure of the dam. Moreover, the shape characteristic of a channel (straight or with bends) influences the evolution of the flash flood along the sloping channel. The findings enhance the understanding of the formation and evolution mechanisms of flash floods due to cascading failures of natural landslide dams, and hence are beneficial for assessing hazard risk and developing mitigation strategies for flash flooding in mountainous areas.

Relationship between seepage water volume and total suspended solids of landslide dam failure caused by seepage: an experimental investigation

BackgroundLandslide dams inevitably demonstrate the potential for catastrophic failure with high-risk damage to life and property at the downstream site. Hence, knowledge of the internal stability of dam materials is a key to predicting the seepage failure of landslide dams. In this study, experiments were conducted to examine the relationship between seepage volume and total suspended solids (TSS) of seepage water based on hydro mechanical constrains. Understanding the relationship between the seepage volume and TSS with hydro-mechanical constraints supports the prediction of the seepage failure of landslide dams at the field level.ResultExperiments were conducted with a mixed sample of silica sands. Seepage water was collected from a flume tank with the facility to measure the hydraulic gradient, vertical displacement, and seepage water volume. Grain size affected the life span of the dam. The seepage volume increased with the increase in the percentage of silica sand S4, whereas TSS increased with the increase in the percentage of silica sand S8. With the increase in the dam height, the dam life decreases for low coeficient of uniformity of the grain size distribution. With the increase in the reservoir size, TSS decreased, and the total seepage volume increased.ConclusionDam failure depends on the particle size, dam geometry, inflow rates, reservoir size, hydraulic gradient, and seepage water volume, and TSS of seepage water. The results indicated that with the increase in fine particles, the life span decreases, and TSS increases. With the increase in the flow rate, the dam life span decreases, and the TSS and seepage volume rate increase.The dam height leads to an increase seepage volume with low TSS, where the life span of the dam also depends on the particle size distribution With the increase in the reservoir size, the seepage water volume decreases with low TSS.

Bayesian lifetime analysis for landslide dams

Landslide dams are a common hazard which threaten downstream human settlement or infrastructure, as their collapse may result in a flash flood. The danger is compounded by the amount of water accumulated; therefore, estimation of the time to failure becomes crucial for assessing engineering risk mitigation procedures. Dam dimension indices, descriptive multivariate analysis and logistic regression have been used to produce a static image of the dam conditions, estimating the probability of failure, but they provide no information of when a failure might occur. We propose a Bayesian model to predict the time to failure of landslide dams, based on imputing missing dam and reservoir measurements via an analysis of their covariate structure. The resulting data is then used in a Bayesian survival model which links the (censored) failure time to dam and reservoir variables. A case study on heterogeneous Italian events is presented, on which our model is tested. Results show that it is possible to produce a probabilistic model of time to failure. The length and height of dams, and the catchment area behind them, are identified as the most important covariates controlling the time to failure. The addition of area-based intercepts confirms the robustness of the methodology. Examples of potential results (forecasting) and possible generalizations of the model are presented.

The relationship among the premonitory factors of landslide dam failure caused by seepage: an experimental study

BackgroundA landslide dam always has the potential for catastrophic failure with high risk for life, cost and, property damage at the downstream site. The formation of a landslide dam is a natural process; thus, minimizing the risk due to its failure is important. Landslide dam failure can be categorized into three types: seepage failure, overtopping and slope failure. As described by other researchers, the established premonitory factors of landslide dam failure are hydraulic gradients, seepage and turbidity as well as vertical displacement and inflow into the reservoir.MethodologyThis study only considered seepage failure and used flume experiments to understand it. Three groups of samples which represented fine, medium and coarse particle sizes, respectively, were prepared by Silica sand S4, S5, S6 and S8 of different proportion. These samples were used to conduct the flume experiments of failure and not failure case.ResultFor failure cases, it was found that GI samples have a higher hydraulic gradient and that the seepage water takes time to exit the dam body—however, the seepage water has more TSS. GII samples also had a higher hydraulic gradient, while the flow of seepage water was faster than that of the fine sample with a low TSS. For GIII samples, the hydraulic gradient was very low in comparison with the GI and GII samples. The GIII samples had TSS values that were quite a bit higher than those of the GII samples and lower than those of the GI samples. Experiments on GI samples failed at each attempt; however, the GI samples with kaolinite did not fail and had a higher TSS value. For a GII sample of a non-failed case, the hydraulic gradient was lower than for GI samples and the seepage water flow was faster but the vertical displacement was constant and TSS was on a decreasing order. For a GIII sample, the hydraulic gradient became constant after reaching its initial peak value and TSS was on a decreasing order with an initially increasing vertical displacement that would become constant.ConclusionSeepage failure of a landslide dam can be predicted by understanding the nature of its premonitory factors. These factors behave differently in different particle size samples. The TSS trend line may be the initial factor for checking the stability of a dam crest. A landslide dam with an increasing TSS order will fail and a decreasing order may not fail. Based on all experiments, it can be concluded that the hydraulic gradient has three stages: 1) it starts to increase and reaches a peak value; 2) it starts to decrease from the peak value and reaches a minimum; and 3) it starts to increase again where the seepage water begins to come out and the vertical displacement starts to increase. Dam failures always occur when seepage water comes out with an increasing TSS and an increasing vertical displacement. Repeated experiments on samples having more fine particles show that if a landslide dam is formed by fine particles, then there would be a high chance of its failure. In case of a constant hydraulic gradient, the landslide dam would be stable whenever there is an increasing vertical displacement and presence of TSS. Similarly, in case of a constant vertical displacement and a decreasing TSS, a landslide dam would be stable.

The evolution of the Samaoding paleolandslide river blocking event at the upstream reaches of the Jinsha River, Tibetan Plateau

A large number of landslides have occurred in the upstream reaches of the Jinsha River, Tibetan Plateau due to the intensity of tectonic movement in the area. Remote sensing and field investigation indicate that one of them, the Samaoding paleolandslide, previously blocked the river. Various river-blocking phenomena are well preserved, including the old landslide dam and deposits, fluvial sediments, and hydrostatic sandy sediment. To better understand the evolution of the Samaoding landslide, the authors carried out thermoluminescence (TL) dating and numerical simulations. The TL analysis shows that the landslide occurred at 10.6 ± 0.5 Ka BP. Discrete element method (DEM) simulation of the landslide based on landform restoration provided results that are consistent with field observations. The simulation indicates that the entire landslide process lasted for 80 s, and the sliding mass reached a maximum velocity of 64 m/s. The landslide formed a landslide dam with a length of 1900 m, a width of 600 m, and a depth of 200 m. The simulation results show that the level of the riverbed at that the time of the landslide was at least 25 m higher than it is today. On the combined basis of the simulation results and field observations, the authors propose explanation that the following valley evolution sequence occurred after river blocking. The landslide dam experienced flood overtopping and then was eroded until it had mostly had been transported away by river flow, and the river then rapidly incised the bedrock to form the present-day landform. Based on the field investigations, the authors summarize the failure mechanism of steep-inclined antidip rockslides and found that tectonics play an important role in the formation of landslide dams (or trigger of landslides) and the failure of landslide dams in an active tectonic environment of Tibetan Plateau.