scholarly journals A Preliminary Study of the Failure Modes and Process of Landslide Dams Due to Upstream Flow

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1115 ◽  
Author(s):  
Xinghua Zhu ◽  
Jianbing Peng ◽  
Cheng Jiang ◽  
Weilong Guo
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Mine Waste ◽  
Failure Process ◽  
Landslide Dam ◽  
Experimental Tests ◽  
Field Investigation ◽  
Dam Failure ◽  
Experimental Conditions ◽  
Landslide Dams

In the process of mineral development, large-scale flash floods (or debris flows) can be induced by the failure of landslide dams formed by the disorganized stacking of mine waste. In this study, the modes and processes of mine waste dam failures were explored using 13 experimental tests based on the field investigation of landslide dams in the Xiaoqinling gold mining area in China. Our 13 mine waste dam experiments exhibited three failure modes: (i) Piping, overtopping, and erosion; (ii) overtopping and soil collapse; and (iii) overtopping and erosion. In addition, the failure processes of the landslide dams included impoundment, seepage, overtopping, and soil erosion. Different experimental conditions would inevitably lead to different failure processes and modes, with the failure modes being primarily determined by the seepage characteristics. Overtopping was the triggering condition for dam failure. The landslide dam failure process was determined based on the particle size of the mine waste and the shape of the dam. These findings will provide a scientific reference for the prevention and mitigation of natural hazards in mining areas.

scholarly journals Scenario Simulation of The Geohazard Dynamic Process of Large-Scale Landslides: A Case Study of The Xiaomojiu Landslide Along The Jinsha River

2021 ◽  
Author(s):  
Jianqi Zhuang ◽  
Kecheng Jia ◽  
Jiewei Zhan ◽  
Yi Zhu ◽  
Chenglong Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Failure Process ◽  
Maximum Velocity ◽  
Field Investigation ◽  
Particle Flow Code ◽  
Dam Failure ◽  
Deformation Analysis ◽  
Maximum Height ◽  
Scenario Simulation ◽  
Jinsha River

Abstract Large-scale landslides often cause severe damage due to their long run-out distances and having disaster chain effects. Scenario simulation has been adopted in the current work to analyze the Xiaomojiu landslide dynamic processes, such as sliding velocity, deposition characteristics, and flood outburst after a landslide-dam failure using Particle Flow Code (PFC-3D) which introduced the changeable friction coefficient and the HEC-RAS software. The landslide characteristics and topography data were obtained via field investigation, whereas high-resolution topographic data (0.17 m) was obtained using an Unmanned Aerial Vehicle (UAV). The results showed that: 1. The landslide presents a scallop shape with a length of 1566 m, a width ranging from 809~1124 m, and an area of 1.34×106 m2. The average thickness and volume of the sliding body is approximately 40 m, 5.1×107 m3. The InSAR deformation analysis showed that the Xiaomojiu landslide has a maximum annual displacement rate of 60 mm/y, and a maximum accumulation deformation of 180 mm since November 25, 2017. 2. From the landslide simulation results, the failure process of the Xiaomojiu landslide lasted for 65 s with a maximum velocity of 78.2 m/s. The deposited area is approximately 2023 m long, 900 m wide, with a maximum height of approximately 149 m. 3. After the landslide blocks the Jinsha River, a landslide-dammed lake with an elevation of 2940 m and a storage capacity of 4.13×109 m3 is formed. The maximum peak flow rate of the breach is 12051.7 m3/s, 43451.4 m3/s, 148635.6 m3/s, and 304544.7 m3/s for the landslide-dammed failure degrees of 15%, 25%, 50%, and 75%, respectively. These results provide a scientific reference for the risk analysis and mitigation of the landslide.

scholarly journals Large-Scale Field Test Study on Failure Mechanism of Non-Cohesive Landslide Dam by Overtopping

2021 ◽  
Vol 9 ◽  
Author(s):  
Liang Li ◽  
Xingguo Yang ◽  
Jiawen Zhou ◽  
Jieyuan Zhang ◽  
Gang Fan
Keyword(s):  
Large Scale ◽  
Discharge Channel ◽  
Failure Process ◽  
Field Tests ◽  
Landslide Dam ◽  
Development Stage ◽  
Dam Failure ◽  
Process Time ◽  
Scale Field ◽  
Large Scale Field

In recent years, landslide lake disasters occur frequently in southwest mountainous areas of China. Considering the influence of dam size and discharge channel location, three large-scale field tests were carried out in a natural river to study the failure process and mechanism of non-cohesive soil landslide dam, and the process and mechanism of non-cohesive landslide dam breach were analyzed. The results show that the dam size and discharge channel location have a significant influence on the breach mechanism of the landslide dam. The dam failure process can be divided into three stages: the initiation stage, the development stage and the failure stage. When the discharge channel is located close to the bank, the width of the breach is smaller, and the volume of the residual dam body is larger. The more stable the dam body is, the longer the breach process time is, and the smaller the peak discharge is. This study can provide a scientific reference for the emergency disposal and risk assessment of landslide dam.

Limit States for Deepwater Flowlines and Risers: Review of the Research Activities at the Submarine Technology Laboratory/COPPE

2003 ◽  
Author(s):  
S. F. Estefen ◽  
T. A. Netto ◽  
I. P. Pasqualino
Keyword(s):  
Ultimate Strength ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Experimental Tests ◽  
Limit States ◽  
Collapse Pressure ◽  
Research Activities ◽  
Structural Resistance ◽  
Buckle Arrestors

Research activities related to the limit states of flowlines and risers conducted at the Submarine Technology Laboratory / COPPE in cooperation with PETROBRAS are presented. The motivation for most of the research programs is associated with deepwater challenges arising from the rigid pipe installations at Campos Basin. Initially ultimate strength of intact pipes are investigated together with aspects related to residual strength, buckling propagation and buckle arrestors. Based on the experimental results numerical models have been correlated in order to be used to generate results for full scale steel pipes. Ultimate strength curves have been then produced as well as the analytical equation representative of these curves. Experimental tests of buckling propagation for small and large scale pipes have also been performed to obtain the bias factor for different equations proposed in the literature. Based on this study an equation for propagation pressure has been recommended. In addition, ring and cylinder buckle arrestors have been tested in order to propose an expression relating crossing over pressure with the arrestor geometries. An overview of the studies aiming at establishing the influence of the reeling method of installation on the failure modes of flowlines and steel catenary risers is presented. It is emphasized the influence of cross-section ovality and weld defect amplification due to plastic bending on collapse pressure and fatigue life, respectively. Finally, the development of a new concept of sandwich pipe for ultra deepwater, combining structural resistance and thermal insulation is discussed.

Comparison on the failure process and mechanism between a debris flow and a landslide dam

2020 ◽  
Author(s):  
Huayong Chen ◽  
Chunran Cao ◽  
Xiaoqing Chen ◽  
Jiangang Chen
Keyword(s):  
Debris Flow ◽  
Water Content ◽  
Failure Process ◽  
Landslide Dam ◽  
Clay Content ◽  
Peak Discharge ◽  
Initial Water Content ◽  
Dam Breach ◽  
Initial Water ◽  
Landslide Dams

<p>Besides the numerous artificial dams, there are some other kind of dams distribute such as the glacier dams, moraine dams, landslide dams, and the debris flow dams in China. Especially, the landslide dams and debris flow ones widely distribute in southwest of China after the M8.0 Wenchuan earthquake. Much attention has been paid to the formation, stability, breach process, and the peak discharge prediction of a landslide dam. However few achievements are obtained on the debris flow dams even if the failure of a debris flow dam has posed great threat to the property and life of residents downstream. In this paper, based on the main difference between a landslide and debris flow dam, experiments were conducted by considering different clay content, the initial water content, and incoming water flow. It indicated that the failure duration of a debris flow dam was about 1.60 times as long as that than that of a landslide dam. The peak discharge at the debris flow dam breach was 5.38 L/s. However, the peak discharge at the landslide dam was 7.50 L/s, which was 1.39 times as big as that of a debris flow dam. Finally, by modifying the existing critical initialization condition for the landslide dams, the critical initialization condition for a debris flow dam was proposed.</p>

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

2021 ◽  
Vol 9 ◽  
Author(s):  
Yan Zhu ◽  
Ming Peng ◽  
Shuo Cai ◽  
Limin Zhang
Keyword(s):  
Decision Making ◽  
Landslide Dam ◽  
Flood Damage ◽  
Total Loss ◽  
Dam Failure ◽  
Optimal Decision ◽  
Landslide Dams ◽  
In Series ◽  
Warning Time ◽  
Peak Flood

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 probability Pf linearly influences the expected life loss and flood damage but does not influence the evacuation cost. The expected total loss significantly decreases with Pf when the warning time was insufficient. However, it would not change much with Pf when warning time is sufficient.

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

2021 ◽  
Vol 9 (5) ◽  
pp. 1263-1277
Author(s):  
Xiangang Jiang ◽  
Haiguang Cheng ◽  
Lei Gao ◽  
Weiming Liu
Keyword(s):  
Field Data ◽  
Failure Process ◽  
Landslide Dam ◽  
Dam Failure ◽  
Dimensionless Length ◽  
Channel Changes ◽  
Outburst Floods ◽  
Characteristics Analysis ◽  
Movable Bed ◽  
The Relationship

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.

scholarly journals The formation processes and development characteristics of sandbars due to outburst flood triggered by landslide dam overtopping failure

2020 ◽  
Author(s):  
Xiangang Jiang ◽  
Haiguang Cheng ◽  
Lei Gao ◽  
Weiming Liu
Keyword(s):  
Failure Process ◽  
Landslide Dam ◽  
Dam Failure ◽  
Average Height ◽  
Formation Processes ◽  
Outburst Flood ◽  
Channel Changes ◽  
River Bed ◽  
Essential Form ◽  
Overtopping Failure

Abstract. Sandbars are an essential form of riverbed morphology which could be affected by landslide dams. However, few studies have focused on the formation processes and development characteristics of sandbars triggered by outburst flood. In such a way, eight group dam failure experiments with 4 to 7 times of dam length movable bed is carried out to study the temporal and spatial distributions of 25 sandbars along the riverbeds, the sandbars geometric characteristics, and the influence of outburst flow hydraulic characteristics on developments of sandbars. The results show that sandbars are formed after peak discharge of outburst flow. The number of sandbars is 0.4 to 1.0 times the ratio of river bed length to dam length. Besides, sandbars have the characteristic of lengthening towards upstream during the failure process. Sandbars' upstream edges have a more extensive development than sandbars downstream edges. The length of a sandbar along the channel changes faster than the sandbar's width and height. The sandbars' length and width are about 10 to 80 and 1 to 7 times of average height, respectively, and the average heights of sandbars are about 1 to 3.5 times the maximum particle size. Sandbars' lengths make a more significant impact on sandbars' volumes than widths and heights. It found that the Froude number has a significant influence on the sediment carrying capacity. And the sediment concentrations in volumes of the outburst flow at the upstream edges of all sandbars are greater than those at the downstream edges of sandbars. Meanwhile, the sediment carrying capacities of the outburst flow at the upstream edges of sandbars are smaller than those at the sandbars' downstream edges. And the differences between the sediment concentrations and the sediment carrying capacities determine the sedimentation or entrainment. The results can reference the research on the river channel's geomorphological characteristics affected by the outburst flood.

scholarly journals Recent Advances in Stability and Failure Mechanisms of Landslide Dams

2021 ◽  
Vol 9 ◽  
Author(s):  
Hongchao Zheng ◽  
Zhenming Shi ◽  
Danyi Shen ◽  
Ming Peng ◽  
Kevin J. Hanley ◽  
...  
Keyword(s):  
Failure Modes ◽  
Risk Mitigation ◽  
Failure Mechanisms ◽  
Landslide Dam ◽  
Evaluation Indexes ◽  
Landslide Dams ◽  
Recent Advances ◽  
Engineering Measures ◽  
Dam Stability ◽  
The Stability

Numerous landslide dams have been induced in recent years as a result of frequent earthquakes and extreme climate hazards. Landslide dams present serious threats to lives and properties downstream due to potentially breaching floods from the impounded lakes. To investigate the factors influencing the stability of landslide dams, a large database has been established based on an in-depth investigation of 1,737 landslide dam cases. The effects of triggers, dam materials, and geomorphic characteristics of landslide dams on dam stability are comprehensively analyzed. Various evaluation indexes of landslide dam stability are assessed based on this database, and stability evaluation can be further improved by considering the dam materials. Stability analyses of aftershocks, surges, and artificial engineering measures on landslide dams are summarized. Overtopping and seepage failures are the most common failure modes of landslide dams. The failure processes and mechanisms of landslide dams caused by overtopping and seepage are reviewed from the perspective of model experiments and numerical analyses. Finally, the research gaps are highlighted, and pathways to achieve a more complete understanding of landslide dam stability are suggested. This comprehensive review of the recent advances in stability and failure mechanisms of landslide dams can serve as a key reference for stability prediction and emergency risk mitigation.

scholarly journals Influence of Internal Structure on Breaking Process of Short-Lived Landslide Dams

2021 ◽  
Vol 9 ◽  
Author(s):  
Chu-Ke Meng ◽  
Kun-Ting Chen ◽  
Zhi-Pan Niu ◽  
Bao-Feng Di ◽  
Yu-Jian Ye
Keyword(s):  
Growth Rate ◽  
Failure Process ◽  
Landslide Dam ◽  
Storage Process ◽  
Dam Breach ◽  
Landslide Dams ◽  
Evolution Characteristics ◽  
Breaking Mechanism ◽  
The Difference ◽  
The Stability

The diversity of the landslide dam structure will result in the difference in the dam body’s seepage. In this paper, based on two kinds of soil bodies of different particle gradations, fourteen groups of structures of the landslide dam are designed to generalize different seepage developments and breaking processes. The study shows that the saturation and seepage evolution characteristics of the landslide dam's seepage have a considerable influence on the landslide dam’s breaking characteristics. An empirical formula is fitted according to the time-seepage degree curve of the landslide dams of different breaking processes to predict the breaking forms of the landslide dams before the dam break. During the water storage process of the landslide dam, the seepage's saturation process inside the dam body reduces the stability of the landslide dam, thus affecting the evolution of the failure process after it has started. In the experiment, it is found that the growth rate of the seepage degree of the landslide dam is inversely proportional to the growth rate of the dam breach area. Although the internal penetration of landslide dams is usually undervalued, the result verifies that the study on the seepage process before the breaking of landslide dam is conductive for further understanding the breaking mechanism of the landslide dam.

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