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1.
在我国西南地区，以塔柱状危岩体崩塌为扰动源的涌浪次生灾害时有发生。涌浪特征与其扰动源的初始形状和破坏模式关系密切，塔柱状危岩体由下至上、空中崩解的破坏模式与颗粒柱体崩塌相似。区别于以往多试验采用的刚体材料和利用运动距离获得初始动力状态的涌浪试验，本研究设计并进行了不同高度和宽度的颗粒柱体在不同水深下自然崩塌的物理模型试验。运用PIV技术分析了颗粒体及水体的运动特征，按颗粒体与水体的相互作用关系将整个过程大致分为了3个阶段，并研究了颗粒柱体初始形态对试验结果的影响。结果表明，颗粒柱体崩塌后的残余体积受颗粒体初始形态影响较大，水深对其影响较小。涌浪产生早期，首浪位置与颗粒运动位置有着良好的对应关系；而后，两者的位置逐渐拉开。颗粒柱体高度越高，首浪最大波高出现时的位置与崩塌颗粒群前端位置的差值越大。这可能与流固相互作用后期水体流速大于颗粒流动速度有关。试验产生的涌浪大多具有完整波形，这与柱状颗粒体的散体性及其覆盖堆积特征对水体的作用呈不均匀性有关。涌浪传播过程中，水体在z方向上抬升幅度具有一定的渐变性。试验分析结果揭示了柱状危岩体引发涌浪的机制特点，为涌浪灾害防治提供了基础资料。  相似文献   

2.
柱状危岩体是三峡库区常见的一种典型地质灾害隐患，其崩塌产生涌浪给库区航运、旅游、生产生活以及人员财产造成巨大威胁和损害。文章基于野外柱状危岩体的成生及运动边界条件，开展了颗粒柱体崩塌产生涌浪的物理试验和数值模拟。结果表明:该数值模型能较好地模拟崩塌涌浪的形成过程、矢量信息以及与水体的相互作用；速度曲线定量地展示了能量的传递；物理试验和数值模拟涌浪高度偏差约3~4 cm；数值模拟堆积区堆积角比物理试验大5%；比前缘运动距离小7%。为柱状危岩体崩塌产生涌浪灾害的预测和预警提供了重要依据。   相似文献   

3.
三峡库区龚家方斜坡2008年11月23日发生崩塌后,其后缘残留大量危岩体,严重威胁长江航道安全。当地政府决定对其进行人工清除,以消除隐患。作者建立了一种以高清摄像机和高频水位计为主的简易涌浪野外观测方法,用以监测爆破产生碎屑流形成的涌浪。以2011年1月17日爆破清方事件为例,文章展示了野外设备安装和监测到的滑坡涌浪过程。监测分析表明,该次爆破碎屑流入水速度约为31 m/s,入水体积约250 m3;产生的涌浪较小,为波群形态,初始涌浪可表达成2个简单三角函数的叠加。该涌浪应急监测方法简便、易行、有效,所得监测数据可为滑坡涌浪研究提供宝贵的野外原始资料;方法可为地质环境条件类似地区的滑坡涌浪简易或应急监测提供借鉴。  相似文献   

4.
库区崩塌落石以直接打击和涌浪的形式威胁航道安全。三维流体力学与固体力学耦合分析崩塌落石产生的涌浪是目前该领域的研究热点和未来发展方向。以三峡库区巫峡剪刀峰河道为例,利用Flow-3D首次建立了一个k-ε湍流模型和GMO碰撞模型的流固耦合模型,假定的落石体积为1.2×104 m3。流固耦合分析结果显示:运动物体在陆地斜坡上进行弹跳、翻滚、滑动;进入水体后,其运动受水体严重影响,运动物体将一部分能量传递给水体,能量传递率约为6.54%;水体获得了能量,最大涌浪达到10 m,但衰减很快,至河道中心线时浪高2.4 m,至对岸边浪高为0.89 m。根据涌浪高度大小进行了航道预警分区,建议将预警区北航道线南移350 m左右,航道内涌浪风险将大大降低,航道安全度得到提高。  相似文献   

5.
黄波林  殷跃平  李滨  冯万里  秦臻  张鹏 《地质学报》2021,95(6):1949-1961
强烈的人类工程扰动和水库蓄水作用导致地质灾害高易发区的水库城镇大多存在滑坡涌浪风险;以往灾难性案例较多,危害巨大.本文构建了以潜在涌浪源调查、变形破坏研究、涌浪危险性分析、脆弱性调查、风险评价和减灾对策分析等六个步骤为主的山区水库城镇滑坡涌浪风险评价技术框架流程.以三峡库区巫山县城为例,遴选离县城最近的龙门寨危岩体进行技术示范.该柱状危岩体体积约30.4×104 m3,当前处于欠稳定—基本稳定状态.颗粒-流体耦合数值模型分析显示在145 m和175 m水位工况下危岩体崩塌将分别产生最大约17.9 m和11.6 m的涌浪.巫山县城密集的码头船只和频繁的旅游船是主要承灾体.旅游船只暴露涌浪中的概率为3.4×10-4/a,超过可接受风险限值.景区码头和古城码头因涌浪而导致的潜在直接经济损失大(超过200万),县城各大码头趸船人员具有高—极高风险.针对当前案例,讨论了四种具体减灾方案.相关研究可为山区水库城镇防灾减灾提供技术支撑和借鉴.  相似文献   

6.
论崩塌滑坡—碎屑流高速远程问题   总被引：3，自引：0，他引：3  
刘传正 《地质论评》2017,63(6):1563-1575
高速远程崩塌滑坡—碎屑流具有规模大、速度快、滑程远、多态化、常转向、冲程多、冲击性和摧毁性等特征。崩塌或滑坡高速远程实质上是其解体后的碎屑流运动形式。碎屑流高速远程与崩塌滑坡规模、物质成分结构、地形高差、沟道形态和引发因素及运动路经的环境等因素密切相关。崩塌滑坡变形破坏形式一般显示为蠕动—拉裂—剪断—滑移—冲出—解体—碎屑流化的过程。崩塌滑坡形成机理主要基于残余强度、蠕变作用和孔隙水压力等理论认识进行解释。碎屑流运动机理主要立足于势能动能转化传递、气体浮托和颗粒流运动理论予以解释。动势能转化、气体浮托作用和颗粒流运动三种解释是层次不同、相互补充的关系,不是彼此独立的。基于成年人在复杂地形下能够奔跑逃生,崩塌滑坡—碎屑流前锋的运动速度5m/s作为高速运动的下限值是比较合理的。崩塌滑坡—碎屑流区域的前后缘高差(H)与前后缘水平距离(L)的比值小于0.4或L/H值大于2.5可作为其远程运动的判据。崩塌滑坡—碎屑流成灾模式包括直接压覆、解体推挤、碰撞冲击、气浪吹袭、激流涌浪、堰塞湖淹没与滑坡坝溃决—洪水泥石流等多种形式。  相似文献   

7.
海底滑坡海啸的颗粒流耦合模型   总被引：1，自引：0，他引：1  
海底滑坡的运动可能引发海啸,破坏离岸设施,威胁海岸带安全。国内外关于海底滑坡引发海啸的研究方兴未艾。采用Mih颗粒流模型控制具弱黏聚力的砂土滑坡运动,利用两相流模型计算岩土体-水体相互作用及RNG湍流模型控制水体运动,构建了基于颗粒流模型的海底滑坡海啸全耦合数值分析方法。通过简单水槽水下滑坡案例进行了海底滑坡海啸全过程研究。数值分析再现了变形滑体的不均一运动、密度分异流动、水滑机制和以波谷为典型特征的涌浪波等典型海底滑坡及海啸现象,这表明数值模型具有有效性。许多海域（包括中国南海北部）都存在弱黏聚力和无黏聚力的水下滑坡,该数值方法值得推广和进一步研究完善。  相似文献   

8.
三峡库区龙门寨危岩体崩塌产生涌浪研究   总被引：1，自引：1，他引：0  
长江两岸高耸的危岩体对航道、沿岸居民带来巨大安全隐患。大宁河属于长江一级支流，龙门寨危岩体位于大宁河上，距离巫山县城仅1 km。利用FLOW-3D软件，模拟了145 m、175 m两种水位工况下龙门寨危岩体崩塌产生涌浪过程和涌浪传播过程。模拟结果表明，涌浪在145 m水位工况下最大浪高约为17.9 m，175 m水位工况下最大浪高约为11.6 m；在巫山县的五个码头处，两种水位工况最大涌浪爬高分别约为10.9 m、3.8 m；根据涌浪高度，对大宁河进行危险分区，145 m水位工况下极高危险区长度约4.4 km，很高危险区长度约1.9 km；175 m水位工况下极高危险区长度约3.0 km，很高危险区长度约1.0 km。研究结果有助于防控龙门寨危岩体潜在涌浪灾害危害，保障大宁河航道和巫山县码头安全，同时也为三峡库区滑坡涌浪灾害提供了预警依据。   相似文献   

9.
清江水布垭库区大堰塘滑坡涌浪分析   总被引：4，自引：0，他引：4  
殷坤龙  杜娟  汪洋 《岩土力学》2008,29(12):3266-3270
2007年6月15日位于水布垭水库巴东县清太平镇的大堰塘滑坡发生滑动,激起高达50 m的巨大涌浪,造成了沿岸的人员伤亡。为了解决大堰塘滑坡引起的涌浪问题,把滑坡引起的涌浪分为体积涌浪和冲击涌浪两部分。根据体积守恒原理及块体水下运动的位移公式求出了初始涌浪的计算公式。把滑坡涌浪衰减过程分为急剧衰减和缓慢衰减两个阶段来考虑,并认为急剧衰减阶段的涌浪的衰减符合指数衰减规律,缓慢衰减阶段符合明槽水流的沿程水头损失规律,对其涌浪的传播和爬坡进行了深入探讨,并与实际调查结果进行了对比分析,该成果对水库库岸滑坡的涌浪传播的研究具有一定的参考意义。  相似文献   

10.
千将坪滑坡是三峡库区支流浅水区滑坡产生涌浪的典型案例,但对大范围、长距离的水动力过程和涌浪灾害分析研究成果较少。基于浅水区滑坡涌浪物理实验的推导公式,更新了FAST涌浪计算系统,构建了相应的涌浪源数值模型,在已有的滑坡涌浪灾害快速评价系统程序中新构建了浅水区滑坡涌浪源数值模型,开展了千将坪滑坡涌浪研究。数值计算区域为18.6 km×11.8 km,包括千将坪滑坡附近的长江干流及支流。计算结果显示,千将坪滑坡产生的最大浪高为38.8 m,最大爬高为36.7 m。最大涌浪空间分布显示大于1 m涌浪的河道长约10.5 km,大于2m涌浪的河道长约9.3 km,大于3 m涌浪的河道长约8 km。大于1 m的波浪影响范围主要集中在青干河和锣鼓洞河,涌浪在河道中传播受地形影响而有快速衰减或放大效应。与多源数据对比表明,涌浪爬高数值相差为±2 m,相关性系数达0.97。建立的涌浪数值模型具有消耗计算资源少、计算速度快、计算结果精度较好等优点。基于水波动力学的浅水区滑坡涌浪源模型将可用于水库区支流或干流浅水区滑坡产生的涌浪问题研究,为大范围长距离滑坡涌浪灾害预测预警提供重要技术支撑。  相似文献   

11.
On June 24, 2015, Hongyanzi slope located in Wushan County of the Three Gorges Reservoir collapsed, generating 5–6-m-high impulse waves, which overturned 13 boats, killed 2 persons, and injured 4 persons. It is the second incident of landslide-generated impulse waves since the 175-m experimental impoundment in 2008. The emergency investigation shows that Hongyanzi landslide is a bedding soil landslide with a volume of 23?×?104 m3 induced by a series of triggering factors such as rainfall, flooding upstream, and reservoir drawdown. The nonlinear Boussinesq water wave model is used to reproduce the impulse waves generated by the landslide of June 24th. The numerical simulation results suggest that the wave propagation process was influenced by the T-shaped geomorphic conditions of river valley, and the coastal areas in the county seat were the major wave-affected areas, which is opposite to the landslide. The numerical wave process accord well with the observed incident, and the investigation values were in good agreement with the calculated values. Moreover, the worst-case scenario of the 7?×?104 m3 deformation mass beside Hongyanzi landslide is potential to generate impulse waves, which was predicted with the same numerical model. This adjacent deformation mass will probably generate impulse waves with maximum height and run-up of 2.2 and 2.0 m, respectively, and only a very few areas in the water course had waves rising to a height of 1 m or above. The research results provide a technical basis for emergency disposal to Hongyanzi landslide and navigation restriction in Wushan waterway. More importantly, it pushes the risk management of the navigation based on the impulse wave generated by landslide. It is advised that the Three Gorges Reservoir and other reservoirs around the world should put more efforts in performing special surveys and studies on the potential hazards associated with landslide-generated impulse waves.  相似文献   

12.
A numerical model has been developed using the finite element method for the simulation of impulse waves generated by landslides. The fluid-like landslide is modeled as a generalized non-Newtonian visco-plastic fluid. A three-phase flow model based on the incompressible viscous Navier–Stokes equations is solved using the finite element method to describe the motion of the three types of fluid in landslide. The conservative level set method is expanded to n-phase flow cases and employed to capture the interface of the three phases: air, water, and the landslide. The overall performance of the approach is checked by a number of validation cases: a Rayleigh–Taylor instability problem to illustrate the capability of the proposed method to deal with interface capturing, a benchmark test of a subaerial landslide generated by an impulse wave is carried out and compared with the published experimental data and numerical results, and finally, the 1958 Lituya Bay landslide generated impulse wave, and its results are compared against a scaled-down experiment and other published numerical results. It can be noted that the current model has an excellent ability to capture the complex phenomena that occurs during the whole process of the landslide-generated impulse wave, and considering the simplified treatment of the landslide and the numerical model, fairly good agreement between computed and experimental results has been observed for all simulation cases.  相似文献   

13.
At about 8:30 p.m. on 27 August 2014, a catastrophic rock avalanche suddenly occurred in Fuquan, Yunnan, southwestern China. This landslide and related impulse water waves destroyed two villages and killed 23 persons. The impulse waves occurred after initiation of the landslide, caused by the main part of the slide mass rapidly plunging into a water-filled quarry below the source area. The wave, comprising muddy water and rock debris, impacted the opposite slope of the quarry on the western side of the runout path and washed away three homes in Xinwan village. Part of the displaced material traveled a horizontal distance of about 40 m from its source and destroyed the village of Xiaoba. To provide information for potential landslide hazard zonation in this area, a combined landslide–wave simulation was undertaken. A dynamic landslide analysis (DAN-W) model is used to simulate the landslide propagation before entering the quarry, while Fluent (Ansys Inc., USA) is used to simulate the impulse wave generation and propagation. Output data from the DAN-W simulation are used as input parameters for wave modeling, and there is good agreement between the observed and simulated results of the landslide propagation. Notably, the locations affected by recordable waves according to the simulation correspond to those recorded by field investigation.  相似文献   

14.
At 4:40p.m. on November 23, 2008, the Gongjiafang slope collapsed on the north bank of Yangtze River in Wu Gorge of Three Gorges Reservoir. The 380,000-m3 sliding mass consisted mainly of cataclastic rock. A video record of the major sliding incident was analyzed using the general laws of physical motion. The analysis indicated that the maximum speed and maximum acceleration of the sliding mass were 11.65?m/s and 2.23?m/s2, respectively, and that the maximum amplitude and the propagation velocity of the water wave near the landslide were 31.8?m and 18.36?m/s, respectively. Wave run-up investigation indicated that the maximum run-up on shore was 13.1?m, which declined to 1.1?m at Wushan dock 4?km away. The incident causes no casualties, but did result in economic losses of RMB five million. The numerical simulation model GEOWAVE was used to simulate and reproduced the impulse wave generated by the landslide; the results were in good agreement with the observed incident. The numerical simulation data were then applied to analyze the decay and amplification effects of the landslide wave in the river course. The field investigations and witness information provide valuable materials for the studies of landslide kinematics and impulse waves generated by landslides. In addition, the research results provide a useful reference for future similar waves generated by landslides in reservoirs.  相似文献   

15.
Landslides of subaerial and submarine origin may generate tsunamis with locally extreme amplitudes and runup. While the landslides themselves are dangerous, the hazards are compounded by the generation of tsunamis along coastlines, in enclosed water bodies, and off continental shelves and islands. Tsunamis generated by three-dimensional deformable granular landslides were studied on planar and conical hill slopes in the three-dimensional NEES tsunami wave basin at Oregon State University based on the generalized Froude similarity. A unique pneumatic landslide tsunami generator (LTG) was deployed to control the kinematics and acceleration of the naturally rounded river gravel and cobble landslides to simulate broad ranges of landslide shapes and velocities along the slope. Lateral and overhead cameras are used to measure the landslide shapes and kinematics, while acoustic transducers provide the shape of the subaqueous deposits. The subaerial landslide shape is extracted from the camera images as the landslide propagates under gravity down the hill slope, and surface reconstruction of the landslide is conducted using the stereo particle image velocimetry (PIV) system on the conical hill slope. Subaerial landslide surface velocities are measured with a planar PIV system on the planar hill slope and stereo PIV system on the conical hill slope. The submarine deposits are characterized by the runout distances and the deposit thickness distributions. Larger cobbles are observed producing hummock type features near the maximum runout length. These unique laboratory landslide experiments serve to validate deformable landslide models as well as provide the source characteristics for tsunami generation.  相似文献   

16.
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   

17.
Subaerial landslides falling into confined water bodies often generate impulsive waves. Damaging landslide tsunamis in Three Gorges Reservoir, China, have struck several times in the last 15 years. On June 24, 2015, a 23?×?104 m3 slope failure occurred on the east bank of the Daning River opposite Wushan Town. The sliding mass intruded into the Three Gorges Reservoir and initiated a reservoir tsunami that resulted in two deaths and significant damage to shipping facilities. A post-event survey revealed the landslide geometry and wave run-up distribution, while an eyewitness video captured most of the landslide motion. Employing these firm constraints, we applied the Tsunami Squares method to simulate the 2015 Hongyanzi landslide and tsunami. The simulation revealed that the landslide experienced a progressive failure in the first few seconds and impacted the water with a maximum velocity of ~?16 m/s. The initial wave propagated to the opposite shore in an arch shape, and the water surface reached a maximum amplitude of ~?11 m near the landslide. Wave amplitude-time curves at four points on the river cross section show that the initial wave reached Wushan town in about 50 s with an average wave velocity of ~?30 m/s. The maximum wave run-ups on the shoreline opposite the landslide are around 6 m and attenuate to less than 1 m beyond 2-km distance. The landslide simulation matches the observed geological profile and the eyewitness video, and the numerical results coincide with the observed wave run-up heights. Nearly 80% of landslide energy is lost due to frictional resistances, but the remaining fraction imparted to the tsunami carried catastrophic consequences to a large region. The numerical results emphasize the efficiency and accuracy of Tsunami Squares method for a “Quick Look” simulation of a potential landslide.  相似文献   

18.
This paper presents a new landslide-generated wave (LGW) model based on incompressible Euler equations with Savage-Hutter assumptions. A two-layer model is developed including a layer of granular-type flow beneath a layer of an inviscid fluid. Landslide is modeled as a two-phase Coulomb mixture. A well-balanced second-order finite volume formulation is applied to solve the model equations. Wet/dry transitions are treated properly using a modified non-linear method. The numerical model is validated using two sets of experimental data on subaerial and submarine LGWs. Impulsive wave characteristics and landslide deformations are estimated with a computational error less than 5 %. Then, the model is applied to investigate the effects of landslide deformations on water surface fluctuations in comparison with a simpler model considering a rigid landslide. The model results confirm the importance of both rheological behavior and two-phase nature of landslide in proper estimation of generated wave properties and formation patterns. Rigid slide modeling often overestimates the characteristics of induced waves. With a proper rheological model for landslide, the numerical prediction of LGWs gets more than 30 % closer to experimental measurements. Single-phase landslide results in relative errors up to about 30 % for maximum positive and about 70 % for maximum negative wave amplitudes. Two-phase constitutive structure of landslide has also strong effects on landslide deformations, velocities, elongations, and traveling distances. The complex behaviors of landslide and LGW of the experimental data are analyzed and described with the aid of the robust and accurate finite volume model. This can provide benchmark data for testing other numerical methods and models.  相似文献   

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