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1.
Accurate prediction of the hydrographs of outburst floods induced by landslide dam overtopping failure is necessary for hazard prevention and mitigation. In this study, flume model tests on the breaching of landslide dams were conducted. Unconsolidated soil materials with wide grain size distributions were used to construct the dam. The effects of different upstream inflow discharges and downstream bed soil erosion on the outburst peak discharge were investigated. Experimental results reveal that the whole hydrodynamic process of landslide dam breaching can be divided into three stages as defined by clear inflection points and peak discharges. The larger the inflow discharge, the shorter the time it takes to reach the peak discharge, and the larger the outburst flood peak discharge. The scale of the outburst floods was found to be amplified by the presence of an erodible bed located downstream of the landslide dam. This amplification decreases with the increase of upstream inflow. In addition, the results show that the existence of an erodible bed increases the density of the outburst flow, increasing its probability of transforming from a sediment flow to a debris flow. 相似文献
2.
Mine waste debris flows continue to occur in China, and the disaster prevention and mitigation of these flows faces severe challenges since the mechanisms determining erosion and transport of mine waste along gullies are not yet fully understood. The erosion and delivery process of mine waste heaps was reproduced through flume experiments with the method based on field survey data of the Daxicha mine waste debris flow gully in the Xiaoqinling gold mining area. The results showed that the erosion and movement of mine wastes could be divided into three modes: minimal sediment movement, sediment sorting and delivery, and a large amount of sediment transfer. Moreover, there was an obvious amplification effect on peak discharge along with the formation and failure of temporary landslide dams during the erosion process. The correlation between the coefficient of peak discharge amplification and three dimensionless influencing factors, flume gradient, dimensionless volume, and dimensionless particle size, were comprehensively analyzed. An empirical formula for the coefficient of peak discharge amplification was proposed and verified based on 16 sets of experimental data. These preliminary results can provide a scientific reference for future research on disaster prevention and mitigation of mine waste debris flows. 相似文献
3.
The erosion and delivery processes of mine waste accumulations were reproduced through flume tests under 13 different experimental condition sets. Analysis of the flume test results showed that different scale model landslides, induced by the incision of mine waste accumulations, slipped into the channel and caused complete or partial blockages, with 28 complete blockages and 122 partial blockages observed during the flume tests. The failure of these temporary landslide dams amplified the peak discharge significantly, with the amplification more obvious when caused by the failure of a complete blockage compared to a partial blockage under the same experimental conditions. In order to explore the threshold conditions of a complete blockage, a new blockage index(Ibs) was developed to represent the degree of blockage. It was found that the threshold value of the blockage index for a complete blockage was around Ibs=4.0. What's more, there was a significant negative correlation between the blockage index and the amplification coefficient of peak discharge caused by the failure of a landslide dam.These preliminary results are intended to provide a scientific basis for future research on the disaster prevention and mitigation of mine waste debris flows, as the processes and mechanisms underlying the erosion and delivery of mine waste accumulations by upstream flows along a gully have not yet been clearly identified. 相似文献
4.
On 23 July 2009, a catastrophic debris flows were triggered by heavy rainfall in Xiangshui gully, Kangding county, southwestern China. This debris flow originating shortly after a rainstorm with an intensity of 28 mm per hour transported a total volume of more than 480×103 m3 debris, depositing the poorly sorted sediment including boulders up to 2-3 m in diameter both onto an existing debris fans and into the river. Our primary objective for this study was to analyze the characteristics of the triggering ra... 相似文献
5.
《山地科学学报》2020,17(1):156-172
Loose deposits, rainfall and topography are three key factors that triggering debris flows.However, few studies have investigated the effects of loose deposits on the whole debris flow process.On June 28, 2012, a catastrophic debris flow occurred in the Aizi Valley, resulting in 40 deaths.The Aizi Valley is located in the Lower Jinsha River,southwestern Sichuan Province, China. The Aizi Valley debris flow has been selected as a case for addressing loose deposits effects on the whole debris flow process through remote sensing, field investigation and field experiments. Remote sensing interpretation and laboratory experiments were used to obtain the distribution and characteristics of the loose deposits, respectively. A field experiment was conducted to explore the mechanics of slope debris flows, and another field investigation was conducted to obtain the processes of debris flow formation, movement and amplification. The results showed that loose deposits preparation, slope debris flow initiation,gully debris flow confluence and valley debris flow amplification were dominated by the loose deposits.Antecedent droughts and earthquake activities may have increased the potential for loose soil sources in the Aizi Valley, which laid the foundation for debris flow formation. Slope debris flow initiated under rainfall, and the increase in the water content as well as the pore water pressure of the loose deposits were the key factors affecting slope failure. The nine gully debris flows converged in the valley, and the peak discharge was amplified 3.3 times due to a blockage and outburst caused by a large boulder. The results may help in predicting and assessing regional debris flows in dry-hot and seismic-prone areas based on loose deposits, especially considering large boulders. 相似文献
6.
The 5.12 Wenchuan Earthquake and the subsequent rainstorms induced a large number of landslides, which later were transformed into debris flows. To evaluate the effect of the earthquake on the sediment supply of debris flows, eight debris flow basins near Beichuan City, Sichuan Province, China were chosen as the study area. The area variations of the debris flow source after the Wenchuan Earthquake and the subsequent rainstorm are analyzed and discussed in this paper. Interpretations of aerial photographs (after the 5.12 Wenchuan Earthquake) and SPOT5 images (after the rainstorm event of September 24, 2008) as well as field investigations were compared to identify the transformation of landslide surface in the study area, indicating that the landslide area in the eight debris flow basins significantly increased. The loose sediment area on the channel bed increased after the rainstorm event. In order to estimate the relationship of the landslide area with the rainfall intensity in different return periods, a model proposed by Uchihugi was adopted. Results show that new landslide area induced by heavy rainfall with 50-year and 100-year return period will be 0.87 km2 and 1.67 km2, respectively. The study results show the Wenchuan earthquake had particular influences on subsequent rainfall-induced debris flow occurrence. 相似文献
7.
《山地科学学报》2019,(11)
Natural dams are formed when landslides are triggered by heavy rainfall during extreme weather events in the mountainous areas of Taiwan.During landslide debris movement, two processes occur simultaneously: the movement of landslide debris from a slope onto the riverbed and the erosion of the debris under the action of high-velocity river flow. When the rate of landslide deposition in a river channel is higher than the rate of landslide debris erosion by the river flow, the landslide forms a natural dam by blocking the river channel. In this study, the effects of the rates of river flow erosion and landslide deposition(termed the erosive capacity and depositional capacity, respectively) on the formation of natural dams are quantified using a physics-based approach and are tested using a scaled physical model.We define a dimensionless velocity index vde as the ratio between the depositional capacity of landslide debris(vd) and the erosive capacity of water flow(ve).The experimental test results show that a landslidedam forms when landslide debris moves at high velocity into a river channel where the river-flow velocity is low, that is, the dimensionless velocity index vde 54. Landslide debris will not have sufficient depositional capacity to block stream flow when the dimensionless velocity index vde 47. The depositional capacity of a landslide can be determined from the slope angle and the friction of the sliding surface, while the erosive capacity of a dam can be determined using river flow velocity and rainfall conditions. The methodology described in this paper was applied to seven landslide dams that formed in Taiwan on 8 August 2009 during Typhoon Morakot,the Tangjiashan landslide dam case, and the YingxiuWolong highway K24 landslide case. The dimensionless velocity index presented in this paper can be used before a rainstorm event occurs to determine if the formation of a landslide dam is possible. 相似文献
8.
牛眠沟流域泥石流形成条件、发展趋势及其防治探讨 总被引：1，自引：0，他引：1
汶川地震使牛眠沟流域变成了一个多泥石流灾害的区域,到目前为止,已经发生7次大规模泥石流灾害。经研究,该流域诱发泥石流灾害的3个基本条件非常发育,而目前正处于发展阶段,在震后5~10年内的雨季,极易发生危害性较大、冲击力较强的大规模降雨型泥石流。如果考虑直接利用主沟内沉积的泥石流堆积物,在主沟堆积区的中上游左右两侧修建约为沟宽一半的交替式拦挡土石坝、在中下游修建与沟宽大致相等的拦挡土石坝及在相邻两坝间修建与沟向相对且具有一定坡度斜坡的土木防治工程,可实现消能与耗能双重目的。 相似文献
9.
The frequency and extent of debris flows have increased tremendously due to the extreme weather and the Wenchuan earthquake on May 12, 2008. Previous studies focused on the debris flow from gullies damming the mountain streams. In this paper, an equation for the run-out distance of debris flow in the main river is proposed based on the dynamic equation of debris flow at different slopes given by Takahashi. By undertaking field investigations and flume experiments, a new calculation method of the volume of debris flow damming large river is obtained. Using the percolation theory and the renormalization group theory it was deduced that the large particles should comprise more than 50% for forming a stable debris flow dam. Hence, the criteria of damming large river by debris flow is presented in terms of run-out distance and grain composition which was then validated through the event of damming river by debris flow at Gaojia gully, the upper reaches of the Minjiang River, Sichuan, China, on July 3, 2011. 相似文献
10.
降雨过程中降雨强度的变化会影响土体渗透率及饱和过程, 从而改变土体的力学性质, 影响泥石流起动模式及破坏规模。为探究不同降雨模式对震后泥石流起动机制的影响, 自制了小比例模型槽, 结合可控雨型的降雨模拟系统, 进行了人工降雨诱发泥石流的室内模型试验; 基于不同降雨模式下泥石流的起动过程分析, 对坡体内部含水率和孔隙水压力的变化规律进行了研究。研究结果表明: 递增型降雨模式下泥石流发生突然, 呈整体滑坡转化为泥石流起动模式, 坡体破坏规模最大; 递减型降雨模式下表现为后退式溃散失稳起动模式; 均匀型降雨模式下则表现为溯源侵蚀起动模式; 中峰型降雨模式下以局部滑坡转化为泥石流起动模式; Ⅴ型降雨模式下则由坡面侵蚀加剧转化为泥石流启动模式, 破坏规模最小。研究结果可以为九寨沟地区泥石流的预报预警提供参考。 相似文献
11.
Due to the special condition of provenance and disaster environment after "5·12" Earthquake, the probability and conditions of the occurrence of gully debris flow change greatly after the event, which make it difficult to prevent disaster effectively. In this study the hydrological model of ground water table in loose sediment is established. According to infinite slope theory, the safety factor of deposits is defined as the ratio of resistance force to driving force. The starting condition of post-earthquake gully debris flow is clearly studied by analyzing the effects of rainfall intensity, seismic strength, slope gradient and mechanical properties on the balance of accumulation body. Then the formulas of rainfall and aftershock threshold for starting of gully debris flow are proposed, and an example is given to illustrate the effect of rainfall, aftershocks and their coupling action on a debris flow. The result shows the critical rainfall intensity decreases as the lateral seismic acceleration and channel gradient increases, while the critical intensity linearly increases as the friction angle increases. 相似文献
12.
Debris flows introduced in landslide deposits under rainfall conditions: The case of Wenjiagou gully 总被引：6，自引：2，他引：4
Debris flows often occur in landslide deposits during heavy rainstorms. Debris flows are initiated by surface water runoff and unsaturated seepage under rainfall conditions. A physical model based on an infinitely long, uniform and void-rich sediment layer was applied to analyze the triggering of debris-flow introduced in landslide deposits. To determine the initiation condition for rainfall-induced debris flows, we conducted a surface water runoff and saturated-unsaturated seepage numerical program to model rainfall infiltration and runoff on a slope. This program was combined with physical modeling and stability analysis to make certain the initiation condition for rainfall-introduced debris flows. Taking the landslide deposits at Wenjiagou gully as an example, the initiation conditions for debris flow were computed. The results show that increase height of surface-water runoff and the decrease of saturated sediment shear strength of are the main reasons for triggering debris-flows under heavy rainfall conditions. The debris-flow triggering is affected by the depth of surface-water runoff, the slope saturation and shear strength of the sediment. 相似文献
13.
The formation of the Wulipo landslide and the resulting debris flow in Dujiangyan City,China 总被引：2，自引：1，他引：1
The Wulipo landslide, triggered by heavy rainfall on July 10, 2013, transformed into debris flow,resulted in the destruction of 12 houses, 44 deaths, and 117 missing. Our systematic investigation has led to the following results and to a new understanding about the formation and evolution process of this hazard. The fundamental factors of the formation of the landslide are a high-steep free surface at the front of the slide mass and the sandstone-mudstone mixed stratum structure of the slope. The inducing factor of the landslide is hydrostatic and hydrodynamic pressure change caused by heavy continuous rainfall. The geological mechanical model of the landslide can be summarized as "instability-translational slide-tension fracture-collapse" and the formation mechanism as "translational landslide induced by heavy rainfall". The total volume of the landslide is 124.6×104 m3, and 16.3% of the sliding mass was dropped down from the cliff and transformed into debris flow during the sliding process, which enlarged 46.7% of the original sliding deposit area. The final accumulation area is found to be 9.2×104 m2. The hazard is a typical example of a disaster chain involving landslide and its induced debris flow. The concealment and disaster chain effect is the main reason for the heavy damage. In future risk assessment, it is suggested to enhance the research onpotential landslide identification for weakly intercalated slopes. By considering the influence of the behaviors of landslide-induced debris flow, the disaster area could be determined more reasonably. 相似文献
14.
Clustering debris-flow events, namely many debris flows simultaneously triggered by a regional rainstorm in a large-scale mountainous area, occurred in four regions of Wenchuan earthquake stricken areas in 2008 and 2010. The characteristics of the clustering debris flows are examined with regard to triggering rainfall, formation process, and relationship with the earthquake by field survey and remote sensing interpretation. It is found that the clustering events occurred nearly at the same time with the local peak rainstorms, and the rainfall intensity-duration bottom limit line for clustering debris flows is higher than the worldwide line. It means that more rainfall is needed for the occurrence of the clustering debris flows. Four kinds of major formation processes for these debris flows are summarized： tributary-dominated, mainstream- dominated, transformation from slope failures, and mobilization or liquefaction of landslide. The four regions has a spatial correlation with the strong- quake-influenced zone with the peak ground acceleration = 0.2 g and the seismic intensity 〉 X. 相似文献
15.
Jiangjia Ravine is a world-famous debris flow valley in Dongchuan,Yunnan Province,China.Every year large numbers of landslides and collapses happened and caused enormous damages to people’s properties and lives.With longtime observation and testing in Jiangjia Ravine we had found out one kind of special landslide which had the characteristics of landslide and collapse.Landslide and collapse supplied sufficient materials for debris flow.When a debris flow broke out,some kind of intergrowth existed among rainfall,landslide and debris flow.In order to study the intergrowth and some key parameters,we carried out artificial rainfall landslide tests and model experiments to observe the phenomena such as collapse,surface slide and surface flow.By observing the experimental phenomena and monitoring water contents,the transformation process among landslide deposits and debris flow under the condition of rainfall had been analyzed.Research results revealed the relationship of this kind of intergrowth among rainfall,landslide and debris flow in Jiangjia Ravine.Meanwhile,it was found that this kind of intergrowth relationship existed only when the moisture content was in a certain range.That is,the critical state seemed to be existed in the transformation process. 相似文献
16.
Extreme Rainfall Events and Associated Natural Hazards in Alaknanda Valley, Indian Himalayan Region 总被引：2，自引：0，他引：2
JOSHI Varun KUMAR Kireet 《山地科学学报》2006,3(3):228-236
Introduction The Himalaya is considered to be the youngest mountains on the earth, and is tectonically very active, and hence inherently (geologically) vulnerable to hazards. Extreme rainfall events, landslides, debris flows, torrents and flash floods due… 相似文献
17.
Debris flow susceptibility assessment using a probabilistic approach: A case study in the Longchi area,Sichuan province,China 总被引：3，自引：0，他引：3
The Longchi area with the city of Dujiangyan, in the Sichuan province of China, is composed of Permian stone and diorites and Triassic sandstones and mudstones intercalated with slates. An abundance of loose co-seismic materials were present on the slopes after the May 12, 2008 Wenchuan earthquake, which in later years served as source material for rainfall-induced debris flows or shallow landslides. A total of 48 debris flows, all triggered by heavy rainfall on 13th August 20l0, are described in this paper. Field investigation, supported by remote sensing image interpretation, was conducted to interpret the co-seismic landslides in the debris flow gullies. Specific characteristics of the study area such as slope, aspect, elevation, channel gradient, lithology, and gully density were selected for the evaluation of debris flow susceptibility. A score was given to all the debris flow gullies based on the probability of debris flow occurrence for the selected factors. In order to get the contribution of the different factors, principal component analyses were applied. A comprehensive score was obtained for the 48 debris flow gullies which enabled us to make a susceptibility map for debris flows with three classes. Twenty-two gullies have a high susceptibility, twenty gullies show a moderate susceptibility and six gullies have a low susceptibility for debris flows. 相似文献
18.
Ming-li Li Yuan-jun Jiang Tao Yang Qiang-bing Huang Jian-ping Qiao Zong-ji Yang 《山地科学学报》2018,15(6):1342-1353
Early warning model of debris flow is important for providing local residents with reliable and accurate warning information to escape from debris flow hazards. This research studied the debris flow initiation in the Yindongzi gully in Dujiangyan City, Sichuan province, China with scaled-down model experiments. We set rainfall intensity and slope angle as dominating parameters and carried out 20 scaled-down model tests under artificial rainfall conditions. The experiments set four slope angles(32°, 34°, 37°, 42°) and five rainfall intensities(60 mm/h, 90 mm/h, 120 mm/h, 150 mm/h, and 180 mm/h) treatments. The characteristic variables in the experiments, such as, rainfall duration, pore water pressure, moisture content, surface inclination, and volume were monitored. The experimental results revealed the failure mode of loose slope material and the process of slope debris flow initiation, as well as the relationship between the surface deformation and the physical parameters of experimental model. A traditional rainfall intensity-duration early warning model(I-D model) was firstly established by using a mathematical regression analysis, and it was then improved into ISD model and ISM model(Here, I is rainfall Intensity, S is Slope angle, D is rainfall Duration, and M is Moisture content). The warning model can provide reliable early warning of slope debris flow initiation. 相似文献
19.
Liang Qiao Xing-min Meng Guan Chen Yi Zhang Peng Guo Run-qiang Zeng Ya-jun Li 《山地科学学报》2017,14(6):1113-1123
A colluvial landslide in a debris flow valley is a typical phenomena and is easily influenced by rainfall. The direct destructiveness of this kind of landslide is small, however, if failure occurs the resulting blocking of the channel may lead to a series of magnified secondary hazards. For this reason it is important to investigate the potential response of this type of landslide to rainfall. In the present paper, the Goulingping landslide, one of the colluvial landslides in the Goulingping valley in the middle of the Bailong River catchment in Gansu Province, China, was chosen for the study. Electrical Resistivity Tomography (ERT), Terrestrial Laser Scanning (TLS), together with traditional monitoring methods, were used to monitor changes in water content and the deformation of the landslide caused by rainfall. ERT was used to detect changes in soil water content induced by rainfall. The most significant findings were as follows:(1) the water content in the centralupper part (0~41 m) of the landslide was greater than in the central-front part (41~84 m) and (2) there was a relatively high resistivity zone at depth within the sliding zone. The deformation characteristics at the surface of the landslide were monitored by TLS and the results revealed that rainstorms caused three types of deformation and failure: (1) gully erosion at the slope surface; (2) shallow sliding failure; (3) and slope foot erosion. Subsequent monitoring of continuous changes in pore-water pressure, soil pressure and displacement (using traditional methods) indicated that long duration light rainfall (average 2.22 mm/d) caused the entire landslide to enter a state of creeping deformation at the beginning of the rainy season. Shear-induced dilation occurred for the fast sliding (30.09 mm/d) during the critical failure sub-phase (EF). Pore-water pressure in the sliding zone was affected by rainfall. In addition, the sliding L1 parts of the landslide exerted a discontinuous pressure on the L2 part. Through the monitoring and analysis, we conclude that this kind of landslide may have large deformation at the beginning and the late of the rainy season. 相似文献
20.
Debris flow in metropolitan area — 2011 Seoul debris flow 总被引：4，自引：2，他引：2
Chan-Young Yune Yun-Ki Chae Joongcheol Paik Gihong Kim Seung-Woo Lee Heung-Seok Seo 《山地科学学报》2013,10(2):199-206
A large number of debris flows occurred simultaneously at around 8:30 to 8:50 a.m. on July 27, 2011, at the center of Seoul, Korea. This area is located in the southern part of Seoul and is a densely populated district. As a result of the debris flow event, 16 people were killed, 30 houses were buried, and 116 houses were damaged around Umyeon Mountain, a relatively small mountain with a height of 312.6 m. Since the debris flow event, field investigations on the initiation and transportation zones of debris flows have been carried out. Rainfall data were collected from the automatic weather stations (AWSs) which are operated by the Korea Meteorological Administration (KMA). Video files recorded by residents were also acquired and used to analyze the flow characteristics of the debris flow. Field investigation shows that about 40 debris flows occurred around Umyeon Mountain and most of the debris flows were initiated by small slope failures. The effects of the precipitation that triggered the debris flows were analyzed as well. A landslide hazard map which considers slope gradient and aspect, strength of soil, hazard record, rainfall conditions, and vegetation, was constructed and compared with the initiation zones of debris flows. 相似文献