人工阶梯-深潭防治地震区泥石流的探索

阶梯-深潭是山区河流中常见的一种具有高效消能作用的河床结构。2009年采用人工阶梯-深潭系统对文家沟滑坡体上的新生泥石流沟治理进行野外治理实验。在主沟上游段人工构筑33级阶梯-深潭,经历当年几次暴雨,由于通过在深潭内耗散水流的大部分能量,阻止了沟谷下切并有效地控制了泥石流的发生。对野外实验和数值模拟的结果分析表明,在一定的流量下,阶梯-深潭发育的河流系统有助于单位时间内单位重量水流能量耗散率将趋于最小,可以提升河流系统的稳定性。在地震区的泥石流沟内构筑阶梯-深潭系统有利于加速其稳定的进程,并减少灾害的发生。     

城市泥石流沟的治理启示——以深沟为例

为研究典型工程措施在泥石流沟治理中的作用及影响,结合野外调查及历史资料,对云南东川城区的深沟泥石流治理进行总结：深沟在一系列坝系群建设和多年植树造林的治理下,发育了一定规模的阶梯一深潭系统,使沟道阻力明显增强（经测河床结构强度5p达0．3以上）,消减了泥石流能量,并保护河床不被侵蚀下切,岸坡稳定;而另一方面林草生长能提...     

Effect assessment of debris flow mitigation works based on numerical simulation by using Kanako 2D

Mitigation works are very essential for mitigation of debris-flow hazards in mountainous areas. Usually, it is difficult to assess the effectiveness of existing mitigation works in a catchment. This paper presented a method for quantitative assessment of debris flow mitigation measures by using Kanako system, a user-friendly GUI-equipped debris flow simulator that allows good visualization and easy interpretation. Kanako 2D (Ver. 2.04) was applied to a case study at Caijia Gully, Sichuan Province, China. Mitigation works including check dams, drainage channel, and deposition basin were constructed in the gully in 2001 and 2006. Kanako 2D can simulate debris flow from steep area to alluvial fan. 1D simulation was applied for assessing the effect of the check dams at the lower part of the gully, and 2D simulation was applied for the effect of the drainage channel and deposition basin on the alluvial fan. The simulation results indicate that debris flow will cause great damage to residential area on the alluvial fan if mitigation measures were not implemented in the gully. For old dams which have been filled up with deposits of previous debris flows, the results show that they still have the function for controlling debris flow due to the gradient reduction of the channel bed in front of the dams by the trapped debris flow deposition. After the comprehensive control of debris flow including trapping, drainage, and deposition in the gully, the simulation results indicate that the risk on the alluvial fan can be reduced to an acceptable level.     

汶川地震后四川省绵竹市清平乡文家沟泥石流灾害调查研究

在2008年5月12日汶川地震后的地震灾区暴发了许多泥石流灾害,其中以四川省绵竹市清平乡文家沟泥石流最为显著。文家沟原来不是泥石流沟,在汶川地震时由于滑坡形成的巨大的滑坡-碎屑流堆积体改变了文家沟的泥石流形成条件,在此后的3个雨季内,文家沟先后暴发了5次大规模和特大规模的泥石流灾害,其中以8.13文家沟泥石流规模和危害最大。8.13文家沟泥石流暴发时的总降雨量为227mm,泥石流持续时间约2.5h,泥石流总量约310×104m3;泥石流造成7人死亡,5人失踪,39人受伤,479户农房被掩埋,直接经济损失4.3亿元。5次大规模和特大规模的泥石流以及洪水仅带走了16%的可以很容易形成泥石流的滑坡-碎屑流堆积物,文家沟如再遭遇较大降雨还会暴发泥石流。即使在今后的雨季中暴发几次规模如8.13泥石流一样大的特大规模泥石流,文家沟在较大降雨下仍然可能暴发泥石流灾害,因此对文家沟泥石流的防治工作将是一个长期的工作。     

九寨沟震区“6·21”泥石流成因与致灾机制研究

2019年6月20日晚九寨沟普降大到暴雨,导致九寨沟景区内卓追沟、下季节海子沟、则查洼沟等多处发生泥石流。3条泥石流沟分别冲出固体物质2.79×104m3、3.7×104m3,2.67×104m3,造成多处停淤挡墙及拦砂坝损坏,并淤埋了景区内的部分道路,造成了交通的短时间中断。根据灾后地面调查和遥感解译,初步查明了本次泥石流灾害的成因和致灾过程机制。灾害成因:地震引发的崩塌滑坡产生大量的新增松散固体物源与原有的沟坡堆积物(包括老泥石流堆积物)在强降水的作用下形成泥石流,因此本次泥石流是地震和降雨共同作用的结果。通过泥石流发生前后各流域沟道纵剖面和典型横断面调查分析,发现泥石流致灾过程机制主要包括:(1)泥石流冲刷沟道使老泥石流堆积物参与泥石流运动、同时诱发沟岸失稳崩塌,因而增强泥石流规模和冲击力等动力学参数;(2)沟道卡口和崩滑体滑入沟道后导致泥石流堵塞,在后续泥石流的作用下发生级联溃决,进而增大泥石流峰值流量和冲击力等动力学参数。在两种机制的共同作用下,泥石流规模和冲击力等参数可能超出防治工程规划设计指标,进而导致防治工程损毁并淤埋道路。因此,建议充分考虑地震与强降雨复合作用下九寨沟景区泥石流风险评估、防治工程规划设计的合理性和可靠性等关键问题,以保障景区安全。     

烧房沟滑坡型泥石流工程治理及效果分析

国内对泥石流治理措施谷坊坝、格栅坝的作用和效果研究较多,而对滑坡型泥石流的综合治理措施和效果研究较少。2010.8.14强降雨过程导致汶川震区映秀镇烧房沟滑坡型泥石流暴发,通过分析其运动过程和现状沟道特征,结合滑坡堵点和沟道深切的特点,治理工程采用防堵防切综合工程结构形式:上游谷防群+中游抗滑桩、挡土板和肋板护脚护底+下游3座格栅坝+渡槽明洞跨越G213,并分析各分项工程作用:减弱龙头动能+控制LS01堵点、保护鞋尖+拦粗放细、顺畅排导。最后利用2010.8.14与2013.7.10的历史降雨量和固体参与量对比、工程治理前后动储量对比和各分项工程治理前后的沟道特点对比,验证了烧房沟滑坡型泥石流综合治理工程的效果良好。为今后震区滑坡型泥石流工程防治提供参考。     

四川省金川县城区红桥沟、蔡家沟泥石流及其防治

红桥沟、蔡家沟为大渡河上游（大金川）右岸的一级支沟,位于四川省金川县城区,曾多次发生过严重的泥石流灾害,直接威胁金川县城的安全。这两条沟的泥石流均为粘性泥石流,重度为2．10—2．25t／m^3,具有松散固体物质以表层滑塌及崩塌补给为主,成灾快,危害严重,活动频率较高,暴雨是泥石流的激发因素等特征。在分析红桥沟、蔡家沟泥石流性质及活动特征的基础上,提出拦、停、排的防治工程设计方案,工程实施后取得了很好的减灾及生态、环境效益。     

四川凉山州美姑县61泥石流灾害研究

四川凉山州美姑县6.1泥石流灾害实例研究表明,该泥石流约为20年一遇的中小规模的泥石流。流域上游短历时强降雨和冰雹天气过程是这次泥石流暴发的诱因,流域内退化的生态环境和中下两岸不稳定边坡以及沟道内大量的松散堆积物为这次泥石流提供了丰富的固体物质来源。泥石流堆积物具有典型的多峰型粒度特征,且有较高的粘粒含量。巨大的泥石流漂砾、石背石现象、龟裂现象、侧积堤和龙头堆积证实了这次泥石流为粘性泥石流。危险度评价表明,采莫洛沟属于高度危险的泥石流沟,危险度为0.67;乃托沟属于中度危险的泥石流沟,危险度为0.58。风险评估结果可知,两沟都属于泥石流高风险区风险度分别为0.52和0.45。高风险区的泥石流灾害给当地的经济社会造成了严重影响并直接造成了较大的人员伤亡和财产损失。     

The deformation analysis of Wenjiagou giant landslide by the distributed scatterer interferometry technique

After the deadly Ms 8.0 Wenchuan earthquake, the Wenjiagou landslide produced steep topography, a narrow gully and abundant loose sediments; these factors have contributed to the high debris flow risk in the Wenjiagou area during subsequent rainy seasons. At least five debris flows have occurred in the Wenjiagou area between September 24, 2008, and September 18, 2010, which resulted in seven casualties and an economic loss of approximately 446 million RMB. To reduce the risk of debris flows and landslides, the Wenjiagou Valley Debris Flow Control Project (WVDFCP), which cost over 2 billion RMB, was carried out and completed in 2011. The control measures of the project effectively reduced the scale and damage of the following debris flows. In this paper, the recent deformation of the giant landslide and its effect on the WVDFCP are evaluated by applying a time-series interferometric synthetic aperture radar (InSAR) technique based on distributed scatterers (DSs) to the Radardat-2 SAR data collected from June 2014 to September 2015. In addition, the experimental results show that most areas of the landslide are stable, with an average deformation rate of less than 5.0 mm/year. The results demonstrate that the control measures of the WVDFCP not only reduced the damage caused by the later debris flows but also contributed to the consolidation of the loose sediments in the Wenjiagou landslide area. The time-series InSAR technique based on the DSs of high-resolution SAR images is an important tool for deformation monitoring of earthquake-induced landslides.     

人工阶梯-深潭破坏案例与稳定性分析

通过2006—2010年4个修建人工阶梯-深潭系统的治理山区河流案例,总结其治理效果和最终破坏原因.以单个阶梯为分析对象,给出其受力表达式,建立单个阶梯-深潭的简化稳定性模型,进而分析来流量和冲刷角变化对其稳定性的影响.单个阶梯的稳定性取决于关键石块粒径、河道坡降、流量和冲刷角.洪水期的洪峰流量和阶梯下游冲刷是阶梯破坏的主要原因,上游来流量增加和冲刷角越大,阶梯越易发生破坏.人工阶梯-深潭系统在洪水期的稳定性是其发挥长期治理效果的关键.     

Design and performance of a novel multi-function debris flow mitigation system in Wenjia Gully,Sichuan

The post-earthquake debris flows in the Wenjia Gully led to the exposure of the shortcomings in the design of the original conventional debris flow mitigation system. A predicament for the Wenjia mitigation system is a large amount of loose material (est. 50 × 10⁶ m³) that has been deposited in the gully by the co-seismic landslide, providing abundant source material for debris flows under saturation. A novel design solution for the replacement mitigation system was proposed and constructed, and has exhibited excellent performance and resilience in subsequent debris flows. The design was governed by the three-phase philosophy of controlling water, sediment, and erosion. An Early Warning System (EWS) for debris flow that uses real-time field data was developed; it issues alerts based on the probabilistic and empirical correlations between rainfall and debris flows. This two-fold solution reduces energy of the debris flow by combining different mitigation measures while minimizing the impact through event forecasting and rapid public information sharing. Declines in the number and size of debris flows in the gully, with increased corresponding rainfall thresholds and mean rainfall intensity-duration (I-D) thresholds, indicate the high efficacy of the new mitigation system and a lowered debris flow susceptibility. This paper reports the design of the mitigation system and analyzes the characteristics of rainfall and debris flow events that occurred before and after implementation of the system; it evaluates the effectiveness of one of the most advanced debris flow mitigation systems in China.     

SPH model for fluid–structure interaction and its application to debris flow impact estimation

On 13 August 2010, significant debris flows were triggered by intense rainfall events in Wenchuan earthquake-affected areas, destroying numerous houses, bridges, and traffic facilities. To investigate the impact force of debris flows, a fluid–structure coupled numerical model based on smoothed particle hydrodynamics is established in this work. The debris flow material is modeled as a viscous fluid, and the check dams are simulated as elastic solid (note that only the maximum impact forces are evaluated in this work). The governing equations of both phases are solved respectively, and their interaction is calculated. We validate the model with the simulation of a sand flow model test and confirm its ability to calculate the impact force. The Wenjia gully and Hongchun gully debris flows are simulated as the application of the coupled smoothed particle hydrodynamic model. The propagation of the debris flows is then predicted, and we obtain the evolution of the impact forces on the check dams.     

Stability of landslide dams and development of knickpoints

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.     

Formation and characteristics of post-earthquake debris flow: a case study from Wenjia gully in Mianzhu, Sichuan, SW China

During the three flood seasons following the Wenchuan earthquake in 2008, two catastrophic groups of debris flow events occurred in the earthquake-affected area: the 2008-9-24 debris flow events, which had a serious impact on rebuilding; and the 2010-8-13/14 debris flow events, which destroyed much of the progress made in rebuilding. The Wenjia gully is a typical post-earthquake debris flow gully and at least five debris flows have occurred there. As far as the 2010-8-13 debris flow is concerned, the deposits of the Wenjia gully debris flow reached a volume of 3.1 × 10⁶ m³ in volume and hundreds of newly built houses were buried. This study took the Wenjia gully debris flow as an example and discussed the formation and characteristics of post-earthquake debris flow on the basis of field investigations and a remote sensing interpretation. The conclusions drawn from the investigation and analysis were as follows: (1) Post-earthquake debris flows were a joint result of both the earthquake and heavy rainfall. (2) Gully incision and loose material provision are key processes in the initiation and occurrence of debris flows and a cycle can be presented as the following process: runoff—erosion—collapse—engulfment—debris flow—further erosion—further collapse—further engulfment—debris flow enlargement. (3) The amount of rainfall that triggered debris flows from the Wenjia gully was significantly less than the average daily rainfall, while the intraday rainfall threshold decreased by at least 23.3%. (4) The occurrence mechanism of Wenjia gully debris flow was an erosion type and there was a positive relationship between debris flow magnitude and rainfall, which fitted an exponential model. (5) There were five representative characteristics of Wenjia gully debris flow: the long duration of the occurring process; the long distance of deposition chain conversion during the process of damage; magnification in the scale of debris flow; and the high frequency of debris flow events.     

黏性泥石流沟床冲刷深度研究

沟床冲刷深度是泥石流灾害防治工程设计最重要的参数之一,但到目前为止,关于黏性泥石流沟床冲刷的研究较少,沟床冲刷深度还没有权威可信的计算方法,是泥石流防治工程设计急需解决的技术问题。详细分析了黏性泥石流及可能冲刷沟床运动过程中受力情况,推导出黏性泥石流沟床最大冲刷深度计算公式。公式表明黏性泥石流沟床冲刷深度随泥石流泥深、泥石流重度和沟床纵比降及沟床堆积土体黏性的增大而增大,随沟床堆积土体内摩擦角的增大而减小。与现有计算方法相比,公式基于严格理论推导,计算结果更为精确,可用于计算已发生泥石流地区的不同频率的泥石流的冲刷深度,并举例说明了计算公式的实用价值,其结果为泥石流防治工程设计提供技术支撑。     

西南某水电站旦波北沟泥石流形成条件及运动特征研究

旦波北沟为雅砻江中游右岸河段的一级支流,历史上曾发生多次泥石流.在查明泥石流形成条件的基础上,分析了旦波北沟泥石流的运动特征,包括泥石流的流速、流量、冲击力.这一结论为评价该泥石流对水电站的建设和安全运行的影响具有现实意义.建议左岸前期施工场地和左岸上游备料场沿江设置挡墙,且场地要注意少占行洪断面,防止泥石流沉积淤塞河...     

甘肃陇南武都区泥石流易发性评价

文章分析了甘肃陇南市武都区泥石流形成的自然环境背景、发育特征及易发性。通过野外实地考察,查明了泥石流的发育情况,在此基础上,采用模糊物元可拓方法对泥石流的易发性进行了评价。分析表明,研究区的泥石流具有分布密度高、冲沟及坡面泥石流成片发育、北岸泥石流较南岸发育且粘性泥石流所占比例大于南岸的发育特征;选取岩性、沟床比降、山坡坡度、完整系数、发育程度、降水、断层密度7个因子构建泥石流易发性评价指标体系。通过易发性评价,研究区104条泥石流沟中,66条为高易发性,占总数的63.5%;32条为中等易发性,占总数的30.8%;6条为低易发性,占总数的5.7%。     

沟岸侧蚀对泥石流形成和运动过程的影响

沟岸被侧蚀掉的松散物质会通过动量交换将能量传递给龙头,从而影响泥石流的形成和运动过程。前人建立了许多模型来研究泥石流的侵蚀过程对泥石流形成和运动过程的影响,但是模型中大多以底蚀作用为前提条件。通过侧蚀模型和底蚀模型两种水槽实验的对比,针对泥石流的形成和运动过程展开研究。实验发现侧蚀作用更有利于泥石流的形成和运动,泥石流的龙头高度和速度都有波动特征,但侧蚀作用使得这种波动特征更加明显。侧蚀作用使得泥石流的龙身速度更快于龙头速度,龙身颗粒源源不断地堆积于龙头,使得龙头有较大的高度和附加坡降,因此,侧蚀条件下龙头的速度更快。     

热水河流域典型泥石流灾害成因机制与协同防治研究

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白龙江中上游泥石流发育极为严重,危害、威胁巨大,研究该区泥石流的成灾模式和致灾模式对泥石流灾害防治、国土空间规划、生态文明建设具有重要的科学意义和实践指导价值。文中在分析白龙江流域中上游241条泥石流形成条件的基础上,对泥石流的成灾模式、致灾模式及泥石流防治进行了分析。研究结果表明：（1）泥石流受地形地貌影响显著,高差...