IMHE OpenIR  > 山地灾害与地表过程重点实验室
堰塞坝漫顶溃决过程实验研究
Alternative Titleexperimental study on the breaching processes of natural dams
Language中文
蒋先刚
Thesis Advisor崔鹏 ; 王兆印
2016
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword堰塞坝 溃决模式 水槽实验 溃决过程 数学模型
Other Abstract

对堰塞坝溃决过程的研究既可掌握堰塞坝的溃决规律,同时也可对抢险工作中关心的溃决模式、溃决流量、溃决历时、淹没范围等进行提前预测,指导抢险工作的开展。通过对灾史数据的收集,分析了国内外典型堰塞湖的主要特征,对宏观上掌握堰塞湖特点和室内实验设计提供参考。利用室内水槽实验,分析了水槽坡度、来水流量、坝型、材料和含水量对溃决过程的影响;探讨了控制因素与溃决流量、溃口尺寸、侵蚀率等参数间的关系;采用理论推导获得了溃口宽度与弗洛德数间的关系;推导得出了不同溃决模式的临界条件;结合水力学和土力学理论,构建了漫顶溃决数学模型,并基于MTLAB平台实现了程序化。主要结论如下:(1)通过对灾史数据的查阅,收集了典型灾害事件中的具有详细参数记载的堰塞坝样本68份。利用获得的数据,掌握了堰塞坝几何特征、材料组成特征、强度特征、渗透和侵蚀规律、地形对堰塞湖库容、形状及对堰塞湖形成的影响。(2)以水槽实验数据为基础,分析了三种溃决模式产生的机制。结果表明,堰塞坝材料的中值粒径和渗透系数越小,来水流量越大,漫顶溃决越易产生。坝体材料渗透系数较大、来水流量较小时,渗流发展充分,引起坝体内孔隙水压力上升、内部侵蚀、土体强度降低,导致滑溃模式发生;坝前水位未超过坝顶前时,会产生入流量与渗流量相等和发生漫顶后出流量长时间与入流量相等两种情况,造成坝体不溃决。并结合颗粒起动理论,考虑以来水流量、渗流、土体强度、自重应力对堰塞坝溃决模式的影响,建立了区分漫顶溃决、滑溃和未溃决模式的临界条件。 (3)堰塞湖溃决溃决过程主要包括溃口缓慢发展阶段(阶段Ⅰ)、溃口迅速发展阶段阶段(阶段Ⅱ)和稳定河床形成阶段(阶段Ⅲ)。整个过程中,泥沙运动由悬移质运动转为推移质强烈运动最终形成粗化层,水沙达到新的平衡。溃口斜坡的破坏主要发生在第Ⅱ阶段,在失稳频率和规模上都较另两阶段大。(4)溃决流量与来水流量、迎、背水坡坡度、坝体材料中值粒径和含水量间呈正相关关系,却随水槽坡度的增加先增加后减小。在其他条件相同时,平均侵蚀率随水槽坡度的增大先增大后减小,随后又增大;来水流量的增大、迎、背水坡坡度的增加、含水量的提高均加大侵蚀率;中值粒径与侵蚀率间呈负相关关系。溃口宽度与深度之比随水槽坡度的增大先增大后减小,与来水流量、迎、背水坡度呈正相关关系,但与细颗粒含量和含水量呈负相关关系。(5)在其他条件相同时,水槽坡度的增大、颗粒材料级配良好和材料中细颗粒含量的增多均促进泥石流的形成。(6)将复杂的堰塞坝溃口简化,采用宽顶堰公式计算溃决流量。引入考虑底床坡降和粒径影响的侵蚀率计算公式,同时补充了概率分布函数反应因材料不均匀性和不连续性引起的溃口斜坡失稳的随机性,新建了能够描述堰塞坝漫顶溃决的数学模型。将模型应用的唐家山堰塞坝、小岗剑堰塞坝、Mantaro堰塞坝和室内堰塞坝溃决计算中。结果显示,溃决流量、溃决历时、溃口宽度、堰塞湖内和泄流槽内水位变化计算值与观测值吻合度较好,验证了所建模型的合理性。 

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The research of the breaching process of landslide dam is useful to understand the principle of dam failure, and predict the concerned factors during emergency such as the breaching modes of dam, the outflow discharge, the duration of dam failure, and the submerge area. Analyzing main characteristics of landslide dams by collecting representative historic data help to understand characteristics of landslide dams and provide details for laboratory experimental design. The influences of flume bed slopes, inflow discharges, dam geometrical shape, material, water content to the process of dam failure were analyzed. The relationships between governing factors and the outflow discharge, the size of dam breach, erosion ratio were discussed. The relationships between the width of dam breach and Froude number were also studied. Meanwhile the critical conditions of different mode of dam breach and outburst debris flow from natural dam failure were deduced. A mathematical model was developed to simulate natural dam failure in contain the theory of hydraulics and soil mechanics. These are main conclusions: (1)Based on the 68 detailed natural dams, the influence of the size, the geometric characters of dam, the soil intensity in dam, the rules of erosion and permeation, the influence of topographic feature to the capacity of lake were analyzed.(2)On the basis of flume experiments, we found critical condition of three dam failure modes. Overtopping mode could be easier happen while the median size and permeation ratio are small and inflow is large. Large permeation ratio, small inflow and permeation will cause pore water pressure increasing, erosion inside, which leads to slope failure.If the discharge of inflow equals seepage before water overtopping, the dam will not breach. Critical conditions between overtopping and slope failure and not failure were established considering influence of the inflow, soil permeation, soil strength, and soil gravity.(3)The processes of natural dam failure include: dam breach gradually developing (stage Ⅰ), dam breach rapidly enlarging stage (stage Ⅱ), and stable riverbed formed stage (stage Ⅲ). In the whole process, sediment movement change from suspended load motion to strong bed load motion. Eventually form an armoring layer, and a new water-sediment balance is reached. The slope of dam breach mainly fail in stage 2, which is more frequent and larger than other stages. (4)Burst discharge has a positive correlation with inflow discharge, upstream slope and downstream slope, median diameter and water content of dam material. However, outflow discharge increases first and then decreases with the increase of flume slope. Under the same other conditions, average erosion rate increases first and then decreases with the increase of flume slope then increases again. The increasing of inflow discharge, upstream slope and downstream slope, and water content will increase erosion rate. Median diameter of dam material has a negative correlation with erosion rate. The ratio of breach width and depth increases first and then decreases with the increasing of flume slope, and it has a positive correlation with inflow discharge, upstream slope and downstream slope, but it has a negative correlation with fine content and water content.(5)Larger flume slope, better gradation granular materials, more fine particle content lead to the debris flow formation easier. (6)A mathematical model which can describe natural dam overtopping burst has been established. The complicated dam breach is simplified and the formula of broad-crested weir is used to calculate burst discharge. The new erosion rate formula considering bed slope and particle size is used in the model. Meanwhile, probability function is used in the model to describe the heterogeneity and discontinuity of soils. The model is applied to failure process of Tangjiashan landslide dam, Xiaogangjian landslide dam and Mantaro landslide dam and small size natural dams tests. The results showed that the calculations of burst discharge, duration, breach width, and the water level variation of barrier lake and evacuation launder, which show a good agreement with observations. 

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/18918
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
蒋先刚. 堰塞坝漫顶溃决过程实验研究[D]. 北京. 中国科学院大学,2016.
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