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1.
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
2.
Landslide hazards triggered by the 2008 Wenchuan earthquake, Sichuan, China 总被引：35，自引：16，他引：19
The 2008 Wenchuan earthquake (M
s = 8.0; epicenter located at 31.0° N, 103.4° E), with a focal depth of 19.0 km was triggered by the reactivation of the Longmenshan
fault in Wenchuan County, Sichuan Province, China on 12 May 2008. This earthquake directly caused more than 15,000 geohazards
in the form of landslides, rockfalls, and debris flows which resulted in about 20,000 deaths. It also caused more than 10,000
potential geohazard sites, especially for rockfalls, reflecting the susceptibility of high and steep slopes in mountainous
areas affected by the earthquake. Landslide occurrence on mountain ridges and peaks indicated that seismic shaking was amplified
by mountainous topography. Thirty-three of the high-risk landslide lakes with landslide dam heights greater than 10 m were
classified into four levels: extremely high risk, high risk, medium risk, and low risk. The levels were created by comprehensively
analyzing the capacity of landslide lakes, the height of landslide dams, and the composition and structure of materials that
blocked rivers. In the epicenter area which was 300 km long and 10 km wide along the main seismic fault, there were lots of
landslides triggered by the earthquake, and these landslides have a common characteristic of a discontinuous but flat sliding
surface. The failure surfaces can be classified into the following three types based on their overall shape: concave, convex,
and terraced. Field evidences illustrated that the vertical component of ground shaking had a significant effect on both building
collapse and landslide generation. The ground motion records show that the vertical acceleration is greater than the horizontal,
and the acceleration must be larger than 1.0 g in some parts along the main seismic fault. Two landslides are discussed as
high speed and long runout cases. One is the Chengxi landslide in Beichuan County, and the other is the Donghekou landslide
in Qingchuan County. In each case, the runout process and its impact on people and property were analyzed. The Chengxi landslide
killed 1,600 people and destroyed numerous houses. The Donghekou landslide is a complex landslide–debris flow with a long
runout. The debris flow scoured the bank of the Qingjiang River for a length of 2,400 m and subsequently formed a landslide
dam. This landslide buried seven villages and killed more than 400 people. 相似文献
3.
汶川八级地震地质灾害研究 总被引：118，自引：15，他引：103
汶川地震触发了15000多处滑坡、崩塌、泥石流,估计直接造成2万人死亡。地质灾害隐患点达10000余多处,以崩塌体增加最为显著,反映出地震对山区高陡斜坡的影响差异性非常大,在山顶上的放大作用非常显著。通过综合分析堰塞湖库容、滑坡坝高以及坝体物质组成和结构,对地震形成的33处坝高大于10m的滑坡堰塞湖进行了评估,划分出极高、高、中和低4种溃决危险。汶川地震滑坡滑床往往不具连续平整的滑面,尖点撞击是极震区滑坡的一大共性,可以分为勺型滑床、凸型滑床和阶型滑床等类型。据实地调查,滑坡附近震毁建筑物垂向震动非常明显,具有地震抛掷撞击崩裂高速滑流三阶段特征。在高速滑流中,发生3种效应:(1)高速气垫效应,滑坡体由较大块石和土构成,具有一定厚度,飞行行程可达1~3km;(2)碎屑流效应,撞击粉碎的土石呈流动状态,特别是含水丰富时,形成长程流滑;(3)铲刮效应,巨大撞击力导致下部岩体崩裂,形成新滑坡、崩塌,但是,其厚度不大,滑床起伏不平。本文以北川城西滑坡和青川东河口滑坡为例,分析了地震滑坡高速远程滑动及成灾机理。北川县城城西滑坡导致1600人被埋死亡,数百间房屋被毁,是汶川地震触发的最严重的滑坡灾难,举世罕见。青川东河口滑坡碎屑流是汶川地震触发的较为典型的高速远程复合型滑坡,滑程约2400m,高速碎屑流冲抵清江河左岸,形成滑坡坝,致使7个村庄被埋,约400人死亡。 相似文献
4.
5.
Activity and distribution of geohazards induced by the Lushan earthquake,April 20, 2013 总被引：3，自引：0，他引：3
Peng Cui Jianqiang Zhang Zongji Yang Xiaoqing Chen Yong You Yong Li 《Natural Hazards》2014,73(2):711-726
An Ms7.0 earthquake, focal depth 13 km, struck Lushan on April 20, 2013, caused 196 deaths and 21 missing, 13,484 injuries, and affected more than two million people. A field investigation was taken immediately after the quake, and the induced hazards were analyzed in comparison with the Wenchuan earthquake. We have identified 1,460 landslides and avalanches and four dammed lakes, which were generally small and concentrated on high elevation. Avalanches and rockfalls developed in cliffs and steep slopes of hard rocks, including Jinjixia of Baosheng Town and Dayanxia of Shuangshi Town, Lushan, and the K317 section the Xiaoguanzi section north to Lingguan Town along the provincial highway S210. Landslides were relatively less, mainly in moderate and small scales, developing in sandstone, shale, and loose colluviums. Only one single large landslide was observed to turn into debris slide-flow. Dammed lakes were formed by avalanches and landslides, all in small size and of low danger degree. The earthquake-induced hazards distributed in belt on the hanging wall along the faults, and their major controlling factors include tectonics, lithology, structure surface, and landform. More than 99 % landslides were within 30 km to the epicenter, and 678 within 10 km, accounting for 46 % of the total; about 50 % landslides were distributed on slopes between 35° and 55°, and 11 % on slope exceeding 75°; 60 % on slopes at the altitudes between 1,000 and 1,500 m, 77 % on slopes between 900 and 1,500 m; and 24 and 62 % in hard rocks and section between hard and soft rocks, respectively. Compared with the case of Wenchuan earthquake, both the number and extension of landslides and avalanches in Lushan earthquake-affected area are much smaller, only 5.53 % in number and 0.57 % in area. The earthquake has increased the instability of slope and potentiality of landslide and debris flow. Accordingly, the active period is expected to be relatively short comparing with that in Wenchuan earthquake-hit area. However, the insidious and concealed hazards bring difficulty for risk investigation. 相似文献
6.
Dynamic process analysis for the formation of Yangjiagou landslide-dammed lake triggered by the Wenchuan earthquake, China 总被引：2，自引：0，他引：2
The damming of rivers by landslides resulting in the formation of a lake was one of the typical secondary geological hazards triggered by the Wenchuan earthquake which occurred on May 12, 2008. Some landslide-dammed lakes were at a high risk of causing further damage since the rainstorm season was expected soon after the earthquake. Understanding the dynamic processes in the formation of landslide-dammed lakes is helpful in planning the mitigation measures. The Yangjiagou landslide-dammed lake was selected as a case study to investigate the typical processes of dam formation. The dynamic simulation of the formation of the Yangjiagou landslide-dammed lake was divided into two steps: the landslide step and the overflow/overtopping step. Two-dimensional discrete element method (DEM) was adopted to investigate the mechanics of the Yangjiagou landslide. The landslide process was found to be controlled by the bond strength and residual friction coefficient of the DEM models. Computational results show that the formation of the landslide dam took approximately 35 s. The maximum velocity of a typical particle was approximately 26.8 m/s. The shallow-water equation and finite difference method were used to analyze the hydrodynamic mechanisms of the overflow process of the landslide-dammed lake. Computational results show that overflow would have occurred 15.1 h after the river was blocked, and overtopping failure occurs for the landslide dam in the rainstorm season when the water flow is large enough, causing a major disaster. 相似文献
7.
地震滑坡是在地震瞬间诱发的滑坡灾害。本文讨论了汶川地震灾区滑坡风险区划与常规滑坡风险区划的区别,认为地震滑坡风险区划应该在危险度区划中增加与地震相关的指标因子,如滑坡震中距和滑坡断层距。从而反映地震动能量对地震滑坡发育的贡献作用。而易损度区划中是难以体现地震因素作用的,这里采用滑坡密度、人口密度、道路密度、建筑物密度、耕地密度这5个指标进行易损度评价。最后采用权重叠加法进行了汶川地震极震区10个县市(面积26175.77km2)的滑坡风险区划,其中高、较高风险区分别占全区面积的9.03%和14.61%。说明震后灾区依然存在一定的滑坡风险。汶川地震极震区中,北川、青川、都江堰、彭州4地应该成为滑坡风险防御的主要地区。对滑坡风险区划结果进行了实地抽样检验,证明区划结果基本符合汶川极震灾区的情况。由此可见,本文介绍的地震滑坡风险区划方法是可靠的。 相似文献
8.
2008年5月12日汶川发生里氏8.0级大地震,在灾区形成了30多个堰塞湖,严重威胁了下游人民群众的生命财产安全,引起了世人对堰塞湖坝体稳定的高度关注。本文在前人研究的基础上,从地形地貌、诱发原因、寿命三个方面总结了堰塞湖坝体形成及存在的机理。重点分析总结了目前堰塞湖坝体稳定性的研究进展,指出影响坝体稳定性的内因为堰塞坝的形态与规模、物质组成与结构,外因为堰塞湖湖水体积;总结了前人关于影响坝体稳定性的关键因素以及室内模型试验的研究成果。最后分析了目前研究存在的问题,展望了未来的研究方向。 相似文献
9.
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
10.
堰塞坝形成机理及稳定性分析 总被引：2，自引：0，他引：2
滑坡、崩塌和泥石流是形成堰塞坝的三种主要方式,其形成堰塞坝的条件非常复杂,涉及因素广泛。另一方面,堰塞坝完全堵江形成堰塞湖在世界各国山区广泛分布,时有发生,造成严重灾害。因此,有必要对堰塞坝形成机理及安全性状评估进行研究。本文主要针对滑坡、崩塌、泥石流和碎屑流形成堰塞坝机理进行介绍并探讨了堰塞坝的破坏机制。同时,通过渗透稳定性、抗滑稳定性和抗冲刷稳定性3个方面评估了堰塞坝稳定性分析,以期为堰塞湖的防治与治理提供科学依据。 相似文献