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1.
Risk assessment development considering the failure of landslide dams often requires the estimation of peak outflow through the breach. The empirical equations based on data from case studies tend to be the first direct approach. This paper conducted an uncertainty analysis when these empirical relations were utilized to predict the peak outflow of a breached landslide dam. The results suggest that the relations derived from manmade dams or embankments typically overestimate the peak outflow about 1/5 to 3/4 of an order of magnitude; and the relations derived from the database of landslide dams have much smaller mean prediction errors and also exhibit broad uncertainty bands. Application of the uncertainly analysis was illustrated by the Tangjiashan landslide dammed lake, formed during 2008 Wenchuan earthquake. In addition, the predicted results from Eq. 1 deduced herein were considered to be the reliable estimate of peak outflow through the breach of landslide dam. 相似文献
2.
Breaching parameters of landslide dams 总被引：11，自引：5，他引：6
Landslide dams pose enormous risks to the public because of the potentially catastrophic floods generated by breaching of
such dams. The need to better understand the threats of landslide dams raises questions about the proper estimation of breaching
parameters (breach size, breaching duration, and peak outflow rate) of landslide dams and the feasibility of applying models
for estimating the breaching parameters of man-made earthen dams to landslide dams. This paper aims to answer these two questions.
In this study, a database of 1,239 landslide dams, including 257 cases formed during the 12 May 2008 Wenchuan earthquake,
has been compiled. Based on records of 52 landslide dam cases with breaching information in the database, empirical models
for estimating the breaching parameters of landslide dams are developed. A comparison study between landslide dams and man-made
earth and rockfill dams is conducted, which shows that the models for man-made earth and rockfill dams are not suitable for
estimating the breaching parameters of landslide dams. Two case studies are presented to show the application of the set of
empirical models developed in this paper. 相似文献
3.
滑坡堰塞坝作为结构松散的堆积物,随着上游水位的不断上涨,其稳定性不断降低,并存在突然溃坝的风险。以唐家山滑坡堰塞坝为研究对象,基于相似原理,开展符合坝体颗粒级配的室内水槽物理模型实验,模拟了不同坝后蓄水量、不同水位和不同颗粒物质组成条件下坝体渗流、漫顶破坏的整个过程。监测结果显示：堰塞坝漫顶溃坝主要分为渗流、漫顶、冲刷和溃决4个过程;坝体堆积颗粒级配越差,坝体允许渗流坡降越小;相同材料配比的坝体,上游水位相同时,坝体底部水平位移最大,且漫顶溃坝时溃口尺寸与蓄水量正相关。该研究结果揭示了堰塞坝漫顶破坏规律,可为堰塞坝溃坝防治提供理论参考。 相似文献
4.
Stability of landslide dams and development of knickpoints 总被引：2，自引：0，他引：2
The Wenchuan earthquake triggered many landslides and numerous avalanches and created 100 odd quake lakes. The quake lakes
may be removed or preserved. The removal strategy was applied to several large landslide dams, which were dangerous because
massive amounts of water pooled up in the quake lakes. The dams could eventually fail under the action of dam outburst flooding,
potentially endangering the lives of people in the downstream reaches. This paper studied the stability of landslide dams
and the development of knickpoints by field investigations and experiments, and analyzing satellite images. The study concluded
that if landslide dams were preserved, they would develop into knickpoints and act as a primary control of riverbed incision
and, thus, reduce the potential of new landslide. The stability of landslide dams depends mainly on the development of the
step-pool system and stream power of the flood flow. If a landslide dam consists of many boulders, a step-pool system may
develop on the spillway channel of the dam, which would maximize the resistance, consume most of the flow energy and consequently
protect the dam from incision. The development degree of the step-pool system is represented by a parameter S
p, which was measured with a specially designed instrument. A preservation ratio of landslide dams is defined as the ratio
of preserved height after flood scouring to the original height of the dam. For streams with peak flood discharge lower than
30 m3/s, the preservation ratio is linearly proportional to S
p. For rivers with a peak flood discharge higher than 30 m3/s (30–30,000 m3/s), the minimum S
p value for stable channel increases with log p, in which p is the unit stream power. For a landslide dam with a poorly developed step-pool system, S
p is smaller than the minimum value and the outburst flood incises the spillway channel and causes failure of the dam. For
preserved landslide dams, sediment deposits in the quake lakes. A landslide dam may develop into a knickpoint if it is stabilized
by long-term action of the flow. Large knickpoints can totally change the fluvial processes and river morphology. Uplift of
the Qinghai–Tibetan Plateau has caused extensive channel bed incision along almost all rivers. For many rivers, the incision
has been partly controlled by knickpoints. Upstream reaches of a knickpoint have a new and unchanging base level. This brings
about a transition from degradation to aggradation and from vertical bed evolution to horizontal fluvial process. Multiple
and unstable channels are prominent in the reaches, upstream of the knickpoints. If hundreds of landslide dams occurred simultaneously
on a reach of a mountain river, the potential energy of bank failure and the slope erosion would be greatly reduced and sediment
yield from the watershed may be reduced to nearly zero. The quake lakes may be preserved long term and become beautiful landscapes.
Streams with long-term unfilled quake lakes have good aquatic ecology. 相似文献
5.
Hasan G. Elmazoghi 《Natural Hazards》2013,68(2):229-248
Dam breach width significantly influences peak breach outflow, inundation levels, and flood arrival time, but uncertainties inherent in the prediction of its value for embankment dams make its accurate estimation a challenging task in dam risk assessments. The key focus of this paper is to provide a fuzzy logic (FL) model for estimating the average breach width of embankment dams as an alternative to regression equations (RE). The FL approach is capable of handling nonlinear behavior, imprecision in discrete measurements, and parameter uncertainty. Historical data from 69 embankment dam failures are used in the development and testing of the FL model. Application of the FL model is also presented for estimating average breach widths of two case studies that have adequately documented data. The accuracy of the FL rule-based model is investigated using uncertainty analysis: the mean prediction error between the FL estimates and the observed average breach widths is very small (=0.03) and comparable to that achieved using the best available RE. Moreover, the FL uncertainty band is found to be approximately ±0.51 order of magnitude smaller than the ±0.56 order of magnitude achieved with the best available RE. The simulation results indicate the potential of the FL model to be used as a predictive tool for estimating the average breach width of embankment dams. 相似文献
6.
Dam-break risk analysis of the Attabad landslide dam in Pakistan and emergency countermeasures 总被引：1，自引：0，他引：1
Xiaoqing Chen Peng Cui Yong You Zunlan Cheng Asif Khan Chengyin Ye Shu Zhang 《Landslides》2017,14(2):675-683
The Attabad landslide dam caused significant property losses and many human casualties in Pakistan, and also greatly affected the operation of the China-Pakistan Karakoram Highway (KKH). This paper discusses the risk of dam breach and hazards to the KKH project construction site following a dam breach. The paper examines the following three topics. (1) The geomorphologic dimensionless blockage index (DBI) and the analogy method were used to analyze the stability of the Attabad landslide dam. The long-term behaviors of landslide dams downstream of the Attabad landslide dam indicate that the risk of a dam breach exists, but the probability of a total dam failure is low. (2) The peak discharge of a potential breach of the Attabad landslide dam was calculated for scenarios in which 1/4, 1/3, 1/2, and total failure of the dam was breached. The potential breach discharge decreases with the downstream distance. (3) The potential impacts of the landslide dam breach on the KKH project construction site were analyzed. Based on the composition of the landslide dam, the probability of a 1/3 dam breach is high. To ensure the safety of downstream areas, disaster preparedness plans that correspond to the 1/2 dam breach scenario should be developed. Based on experience in addressing the landslide dam that was caused by the Wenchuan Earthquake, artificial controlled drainage measures are suggested and provide a technical reference for addressing the Attabad landslide dam and achieving recovery and normal operation of KKH. 相似文献
7.
The breach of landslide dam often causes significant disaster in the inundated area; the prediction of breach hydrograph is in high demand for the dam breach risk evaluation. In this study, according to the model tests and Tangjiashan landslide dam breach case, the surface erosion accompanied by intermittent mass failure is known as the key breaching mechanism for landslide dam due to overtopping failure. The downstream slope angle would gradually decrease during the dam-breaching process, whereas a planar wedge failure occurs when the breach slopes at the dam crest and downstream breach channel fail. Based on the breach mechanism, a numerical model for landslide dam breach due to overtopping is developed to simulate the coupling process of water and soil. The model focuses on the breach morphology evolution during the breaching for the sake of the improvement of breach hydrograph prediction. Furthermore, the model can handle one- and two-sided breach, as well as incomplete and base erosion at the vertical direction. The case study of Tangjiashan landslide dam-breaching feedback analysis testifies the rationality of the present model with the relative errors less than 10% for peak discharge, final breach widths, and time to peak. The sensitivity analysis indicates that the final breach depth and soil erodibility affect the breach flow prediction of the landslide dam significantly, whereas the one- or two-sided breach mode is less sensitive. 相似文献
8.
Landslide dam failure can trigger catastrophic flooding in the downstream. However, field observation of such flooding is
rarely available, while laboratory experimental studies are sparse. The mechanism of landslide dam failure and the flood has
so far remained insufficiently understood. Here, we present an experimental investigation of landslide dam failure and the
flood. A total of 28 runs of experiments are carried out in a flume of 80 m × 1.2 m × 0.8 m, with differing inflow discharge,
dam composition, dam geometry, and initial breach dimension. An array of twelve automatic water-level probes is deployed to
measure the stage hydrographs along the flume, and the video recording of the dam failure processes facilitates an estimation
of the widening of initial breach. Under the present experimental conditions with dams composed of homogeneous materials,
landslide dam failure is primarily caused by erosion of overtopping flow, and lateral mass collapse is also considerable during
the cause of breach widening. Cohesive clay may act to mitigate the seepage through the dam and thus its subsidence and appreciably
modulate the dam failure process and the flood. However, the impacts of clay may be readily overwhelmed by a large inflow
discharge and initial breach. Gravels in the dam may appreciably depress the rate of the dam failure process and thus modify
the flood. The present work provides new experimental data set for testing mathematical models of the flood flow due to landslide
dam failure. 相似文献
9.
对土石坝溃决模拟技术的最新研究成果进行了总结和评价,在此基础上对该研究领域今后的研究工作提出了若干建议,包括:应研究提出不同坝型溃决可能性分析评价方法;针对不同坝型开展溃坝离心模型试验,揭示在不同致灾因子作用下,土石坝溃决机理和溃口发展过程;开展土石坝初始管涌形成以后发展过程的试验研究,揭示孔流转变为堰流的控制条件;针对溃坝水流的流线曲率较大、溃坝水流大多是非恒定超临界流以及筑坝材料粒径级配范围变化大等特点,开展大型溃坝水工水力学模型试验,揭示不同坝型的溃口流量过程、泥沙输移及下游河道洪水演进规律。 相似文献
10.
堰塞坝是由于崩塌、滑坡、泥石流等形成的天然坝体,不同于人工土石坝,堰塞坝坝体结构松散,颗粒级配不均匀,在较高水头作用下坝体可能发生渗透破坏而导致溃坝,严重威胁下游人民群众的生命及财产安全。由于堰塞坝存在较大粒径颗粒,常规的渗透试验装置难以满足要求,本文研制了直径为60cm的大直径渗透试验仪,进行了不同堰塞坝级配材料的渗透破坏试验,并探讨了堰塞坝体材料渗透特性的主要影响因素。研究发现:（1）堰塞坝材料的渗透破坏形式取决于材料级配,粗颗粒含量较多时为管涌破坏,细颗粒含量较多或粒径缺失时为流土破坏;（2）堰塞坝渗透系数随干密度的增大而减小,主要取决于细料填充粗料孔隙的程度,单独使用不均匀系数或曲率系数不适用于评价渗透系数的变化;（3）基于试验数据提出了用于堰塞坝渗流破坏形式的判别公式,并推导出堰塞坝管涌破坏的临界水力坡降计算公式。 相似文献
11.
Jia-Jyun Dong Yu-Hsiang Tung Chien-Chih Chen Jyh-Jong Liao Yii-Wen Pan 《Engineering Geology》2011,117(1-2):52-61
Landslides may obstruct river flow and result in landslide dams; they occur in many regions of the world. The formation and disappearance of natural lakes involve a complex earth–surface process. According to the lessons learned from many historical cases, landslide dams usually break down rapidly soon after the formation of the lake. Regarding hazard mitigation, prompt evaluation of the stability of the landslide dam is crucial. Based on a Japanese dataset, this study utilized the logistic regression method and the jack-knife technique to identify the important geomorphic variables, including peak flow (or catchment area), dam height, width and length in sequence, affecting the stability of landslide dams. The resulting high overall prediction power demonstrates the robustness of the proposed logistic regression models. Accordingly, the failure probability of a landslide dam can also be evaluated based on this approach. Ten landslide dams (formed after the 1999 Chi-Chi Earthquake, the 2008 Wenchuan Earthquake and 2009 Typhoon Morakot) with complete dam geometry records were adopted as examples of evaluating the failure probability. The stable Tsao-Ling landslide dam, which was induced by the Chi-Chi earthquake, has a failure probability of 27.68% using a model incorporating the catchment area and dam geometry. On the contrary, the Tangjiashan landslide dam, which was artificially breached soon after its formation during the Wenchuan earthquake, has a failure probability as high as 99.54%. Typhoon Morakot induced the Siaolin landslide dam, which was breached within one hour after its formation and has a failure probability of 71.09%. Notably, the failure probability of the earthquake induced cases is reduced if the catchment area in the prediction model is replaced by the peak flow of the dammed stream for these cases. In contrast, the predicted failure probability of the heavy rainfall-induced case increases if the high flow rate of the dammed stream is incorporated into the prediction model. Consequently, it is suggested that the prediction model using the peak flow as causative factor should be used to evaluate the stability of a landslide dam if the peak flow is available. Together with an estimation of the impact of an outburst flood from a landslide-dammed lake, the failure probability of the landslide dam predicted by the proposed logistic regression model could be useful for evaluating the related risk. 相似文献
12.
The standard procedure in Quebec, Canada, for evaluating the failure of an embankment dam, per the Loi sur la sécurité des barrages, specifies a 30-min-long failure scenario with a breach width equal to four times the maximal height of the dam. We demonstrate a new method for evaluating the flood overtopping failure scenario for embankment dams with concrete upstream slope protection, using Toulnustouc dam for example computations. Our new methodology computes safety factors for a range of potential failure mechanisms taking into account geotechnical, hydraulic, and structural factors. We compile the results of our investigations of the various dam failure mechanisms and compare the corresponding dam failure hydrographs to the current hydrograph specified in the standard analysis procedures. Our investigations tend to invalidate the current standard procedures for evaluating the failure of rock-fill dams with concrete upstream faces, by indicating that the current standard procedures underestimate the peak failure discharge and overestimate the time to the peak discharge. 相似文献
13.
Anika Braun Sabatino Cuomo Stefano Petrosino Xueliang Wang Luqing Zhang 《Landslides》2018,15(3):535-550
A smoothed particle hydrodynamics (SPH) numerical modeling method implemented for the forward simulation of propagation and deposition of flow-type landslides was combined with different empirical geomorphological index approaches for the assessment of the formation of landslide dams and their possible evolution for a local case study in southwestern China. The SPH model was calibrated with a previously occurred landslide that formed a stable dam impounding the main river, and it enabled the simulation of final landslide volumes, and the spatial distribution of the resulting landslide deposits. At four different sites on the endangered slope, landslides of three different volumes were simulated, respectively. All landslides deposited in the main river, bearing the potential for either stable impoundment of the river and upstream flooding scenarios, or sudden breach of incompletely formed or unstable landslide dams and possible outburst floods downstream. With the empirical indices, none of the cases could be identified as stable formed landslide dam when considering thresholds reported in the literature, showing up the limitations of these indices for particular case studies of small or intermediate landslide volumes and the necessity to adapt thresholds accordingly for particular regions or sites. Using the occurred benchmark landslide as a reference, two cases could be identified where a complete blockage occurs that is more stable than the reference case. The other cases where a complete blockage was simulated can be considered as potential dam-breach scenarios. 相似文献
14.
Corrado Cencetti Andrea Fredduzzi Ivan Marchesini Mara Naccini Paolo Tacconi 《Computational Geosciences》2006,10(2):201-219
The analysis of the flood hazard related to the areas downstream of landslide dams is one of the most interesting aspects
of studying the formation and the failure of natural dams. The BREACH code [14], simulating the collapse of earthen dams, both man-made and naturally formed by a landslide, was chosen in order to analyse
the case of the Valderchia landslide (central Italy). The bed-load transport formula used in BREACH (Meyer-Peter and Muller,
modified by Smart [27]) is based on flume experiments with well-sorted sediments. Such a methodology probably makes this equation not very suitable
for describing the sediment transport peculiar to a landslide body presenting a very poor material sorting. The Schoklitsch
[26] formula was implemented into the programme as an alternative to the Smart equation. However, because the landslide deposits
may often have a strongly bimodal grain–size frequency curve, the percentile D
50 (the typical granulometric parameter requested by bed-load sediment transport formulas) can sometimes correspond to one of
the grain-size classes which are really present to a lesser degree. To consider this phenomenon, the BREACH programme (version
7/88-1) was implemented with a new procedure that calculates two granulometric curves, one for each mode of the original distribution,
and evaluates transport of the landslide material separately. Results of the analysis show that the model is very sensitive
to the bed-load equation and that the procedure implemented to consider the eventual bimodal distribution of the dam material
simulates the armouring phenomenon (which can stop the erosion of the dam during the overtopping phase). 相似文献
15.
针对缺乏地形条件和工程处置措施对堰塞坝溃决过程影响研究的现状,采用4种河床坡度(0°、1°、2°、3°)和3种泄流槽横断面型式(三角形、梯形、复合型),开展了堰塞坝溃决的模型试验。通过分析堰塞坝的溃决流量、溃决历时、溃口发展和坝体纵截面演变过程,研究了不同河床坡度和泄流槽横断面对堰塞坝溃决过程的影响规律。试验结果表明:(1)堰塞坝溃决过程可分为3个阶段。阶段Ⅰ:溃口形成阶段,溃决流量较小;阶段Ⅱ:溃口发展阶段,水流下蚀及侧蚀强烈,溃决流量到达峰值;阶段Ⅲ:衰减-平衡阶段,粗化层形成,溃口停止发展。(2)河床坡度增加意味着下游坝坡、坝顶及泄流槽的坡度增加,导致水流侵蚀能力增强,溃口下切迅猛,因此在0°～3°范围内河床坡度越大,峰值流量越大,峰现时间越早,溃决流量过程曲线越趋于“高瘦型”,且残留坝高越小。(3)泄流槽横断面型式不同导致其槽深、槽宽和侧坡坡度不同,进而影响溃口发展和溃决流量。三角形槽的水土作用面积小,溃口下切及展宽速率最高,峰值流量最大,峰现时间最早;梯形槽的槽底高程最高,水土作用面积最大,溃口下切速率最低,峰现时间最晚;而复合槽介于前两者之间。试验成果将为堰塞坝应急抢险和工... 相似文献
16.
Sammen Saad Sh. Mohamed T. A. Ghazali A. H. Sidek L. M. El-Shafie A. 《Natural Hazards》2017,87(1):545-566
The study of dam-break analysis is considered important to predict the peak discharge during dam failure. This is essential to assess economic, social and environmental impacts downstream and to prepare the emergency response plan. Dam breach parameters such as breach width, breach height and breach formation time are the key variables to estimate the peak discharge during dam break. This study presents the evaluation of existing methods for estimation of dam breach parameters. Since all of these methods adopt regression analysis, uncertainty analysis of these methods becomes necessary to assess their performance. Uncertainty was performed using the data of more than 140 case studies of past recorded failures of dams, collected from different sources in the literature. The accuracy of the existing methods was tested, and the values of mean absolute relative error were found to be ranging from 0.39 to 1.05 for dam breach width estimation and from 0.6 to 0.8 for dam failure time estimation. In this study, artificial neural network (ANN) was recommended as an alternate method for estimation of dam breach parameters. The ANN method is proposed due to its accurate prediction when it was applied to similar other cases in water resources.
相似文献17.
The present study focuses on the emergency response measures for landslide dams. This work presents a series of centrifuge model tests conducted on the draining processes of barrier dams that are based on the grain composition of the Tangjiashan landslide dam. The effects of diversion channels with trapezoid, triangular, and compound sections on the discharge, process, and size of the residual dam are discussed. The characteristics of the flow erosion during the process of discharge in the different channels are analyzed based on hydrodynamics. The results suggest that a diversion channel with a compound section has a higher initial discharge efficiency and lower peak flow, and the flow process curve corresponds to a “chunky-type.” The draining from this type of a diversion channel could clearly reduce the flood pressure of the river downstream and make the entire process smoother. Thus, the excavation of a diversion channel with a compound section is an efficient and safe method for landslide dam emergency mitigation. 相似文献
18.
终碛坝广泛分布于世界各地的高山和极高山区。为了探究终碛坝的溃决过程,了解溃口的演变特征,文章以嘉龙错终碛坝的原位实验,模拟了终碛湖漫顶溃决过程。通过分析实验结果发现:（1）根据观察,将终碛坝溃决过程划分为坝体下游坡面冲刷、“溯源侵蚀”、出水口下切和溃口拓宽四个阶段。（2）上游湖区崩塌体激发的涌浪会造成溃口内的瞬时流量增加数倍,从而使得在有涌浪和无涌浪的条件下,“溯源侵蚀”过程出现陡坎和斜坡两种下切型。（3）通过分析溃口下切侵蚀过程,发现溃口的下切侵蚀发展过程主要受到坝体孔隙比和细粒含量的影响,并且溃口中点侵蚀率与水流剪应力存在一定的线性关系,符合线性侵蚀模型。通过分析发现,嘉龙错终碛坝的侵蚀系数为0.051,临界启动应力为237.64 Pa。与堰塞坝相比,可侵蚀系数比更小,而临界启动应力更大。 相似文献
19.
Field testing of erodibility of two landslide dams triggered by the 12 May Wenchuan earthquake 总被引：4，自引：3，他引：1
A strong earthquake of magnitude 8 in Richter scale, occurred in Sichuan Province, China on 12 May 2008, triggered about 257
landslide dams. The erodibility of fresh landslide deposits plays an important role in evaluating the initiation and development
of breaching of such landslide dams. In this research, field jet index tests were conducted shortly after the earthquake at
27 locations on the Hongshihe landslide dam and the Libaisi landslide dam. The purpose of these tests was to investigate the
erodibility of freshly deposited landslide soils. The landslide deposits are broadly graded. The bulk density increases and
the coefficient of erodibility decreases with the depth of deposition. The erodibility of the fresh landslide deposits falls
into a moderately resistant category and the fresh deposits are much more erodible than the native geomaterials before the
earthquake. The main factors that control soil erodibility are found to be grain-size distribution, void ratio, fines content,
and plasticity index. Particularly, the coefficient of erodibility decreases exponentially with the degree of compaction.
Two empirical equations are developed for estimating the coefficient of erodibility and critical erosive shear stress of the
freshly deposited landslide soils based on their basic soil properties. 相似文献
20.
An extreme rainfall event on August 9, 2009, which was close to setting a world record for 48-h accumulated rainfall, induced the Xiaolin deep-seated landslide, which was located in southwestern Taiwan and had volume of 27.6?×?106?m3, and caused the formation of a landslide dam. The landslide dam burst in a very short time, and little information remained afterward. We reconstructed the process of formation and failure of the Xiaolin landslide dam and also inferred the area of the impoundment and topographic changes. A 5?×?5-m digital elevation model, the recorded water stage of the Qishan River, and data from field investigation were used for analysis. The spectral magnitude of the seismic signals induced by the Xiaolin landslide and flooding due to failure of the landslide dam were analyzed to estimate the timing of the dam breach and the peak discharge of the subsequent flood. The Xiaolin landslide dam failure resulted from overtopping. We verified the longevity of the Xiaolin landslide dam at about 2 h relying on seismic signals and water level records. In addition, the inundated area, volume of the impoundment behind the Xiaolin landslide dam, and peak discharge of the flood were estimated at 92.3 ha, 19.5?×?106?m3, and 17?×?103?m3/s, respectively. The mean velocity of the flood-recession wave front due to the dam blockage was estimated at 28 km/h, and the peak flooding velocity after failure of the dam was estimated at 23 km/h. The Xiaolin landslide provides an invaluable opportunity for understanding the mechanism of deep-seated landslides and flooding processes following a landslide dam failure. 相似文献