桃曲坡水库除险加固后漫坝风险研究

运用漫坝风险分析理论和风险评价标准,结合桃曲坡水库除险加固工程,考虑影响漫坝的洪水、风浪、库容、泄水能力等不确定性因素,建立了桃曲坡水库大坝在洪水与风浪联合作用下的漫坝风险模型,计算了大坝在洪水与风浪联合作用下的漫坝风险及安全可靠度.结果表明,漫坝风险值均小于漫坝安全评定标准,大坝安全.研究成果可为水库管理部门提供科学依据,并为充分发挥桃曲坡水库的防洪兴利效益提供技术支撑.     

突发洪水时山区中小水库漫坝风险的极大熵分析

水库漫坝事故是大坝失事的常见情形,分析水库漫坝的风险在水库漫坝预测中十分重要。基于突发洪水时水库漫坝风险的特征分析,定义一种水库漫坝极限状态函数,构建突发洪水漫坝极限状态风险的极大熵模型,以确定漫坝风险的概率密度函数。采用BP神经网络方法,对水库漫坝极限状态函数进行拟合,结合二次四阶矩法计算水库漫坝风险的概率密度函数,给出求解水库漫坝风险概率的算法步骤,进一步计算出水库漫坝风险的概率值,为水库漫坝的预测和防范提供科学依据。最后,通过一座山区小型水库实例计算分析,表明这种极大熵法的结果与其他分析方法的结果非常接近,且计算效率较高。     

极端降水条件下土石坝漫坝风险研究

以某水库的挡水土石坝为研究对象,基于随机微分方程推求极端降水条件下电站入库和下泄洪水过程线,并结合不同调节水位、风浪、雍高、是否正常泄洪等因素,采用蒙特卡罗法计算大坝的漫坝风险。结果表明,在正常工况下,土石坝漫坝风险概率几乎都在可接受的10-6数量级内;在泄洪失效工况下,考虑防浪墙的漫坝风险概率几乎在可接受的10-6数量级内,总体偏安全;在泄洪失效工况下,不考虑防浪墙的漫坝风险概率均显著高于可接受的10-6数量级,有漫坝风险。     

漫坝风险分析在水库防洪中的应用

综合应用随机水文学、随机水力等等学科知识，全面考虑洪水、风浪、库容和泄水能力的不确定性、建立了土坝对抗洪水和风浪联合作用下的漫坝风险理论，并提出了风险取值标准。此法是防洪减灾的一种辅助策略。可在坝体坚固、管理人员素质较高的大型水库推广应用。综合     

漫坝风险分析在小型水库运行管理中的应用

大连是一个严重缺水的城市,为了更好的利用有限的水资源,对非病险水库,在汛期把洪水作为宝贵的水资源尽可能多地加以存蓄。但是,水库蓄水过多,就会发生土石坝漫顶溢流的情况。为此可以通过漫坝风险分析计算,取得土石坝对抗洪水与风浪联合作用下的漫坝风险的定量数据来确定小型水库的蓄水水位。     

孤立波漫坝模型试验研究

水库环境中发生的滑坡涌浪或洪水波传播到大坝附近时会沿着坝体继续爬升,严重时可能会发生漫坝。漫坝水流对下游所造成的危害往往是毁灭性的。为了研究冲击波漫坝时的水力特征,在试验水槽中用孤立波来模拟涌浪漫坝过程。试验中发现孤立波最大漫坝高度发生在坝顶紧靠迎水坡处,且各漫坝指标与静水深度、相对波高、坝前角度、坝顶宽度等控制参数有关。通过对无量纲参数的多元回归分析,建立了漫坝体积、最大漫坝高度和漫坝持续时间的经验计算公式,揭示了孤立波漫坝水力特性与各控制参数间的关系,可为大坝设计及水库漫坝险情应急处理提供参考。     

土石坝洪水漫顶模糊风险分析

基于大坝漫顶风险分析理论,建立漫顶失事模糊风险模型,并以新疆玛纳斯河夹河子水库为例,对其土石坝洪水漫顶模糊风险进行评估。得出主要结论,该水库大坝平均漫顶失事模糊风险率为5．02×10^-3,超过了我国大坝风险评价标准。综合评定该大坝的洪水漫顶破坏风险较大。     

基于水库管理中漫坝风险理论分析的运用

在水利工程管理科学中,一个非常重要的组成部分为漫坝风险分析,这一理论对于北方地区的水利防洪来说,漫坝风险分析是基本的理论基础和保证。通过与具体工程案例的结合,对水库漫坝从风险角度进行分析,对漫坝风险进行理论讲解,最终建立了漫坝风险分析理论,这一理论是建立在土坝对风浪和洪水联合作用下进行抵抗的基础之上的。     

区间分析在漫坝风险评判中的应用

运用区间分析理论,在综合考虑起调水位、洪水、风浪、坝顶高程等方面不确定性的基础上,建立土坝漫坝风险模型,给出漫坝风险区间和风险度计算方法,并对风险度[0,1]采用5级制划分,为漫坝风险评判提供依据。实例工程计算结果表明,区间分析法是漫坝风险评判中行之有效的方法。     

基于水库管理中漫坝风险理论分析的运用

在水利工程管理科学中,一个非常重要的组成部分为漫坝风险分析,这一理论对于北方地区的水利防洪来说,漫坝风险分析是基本的理论基础和保证.通过与具体工程案例的结合,对水库漫坝从风险角度进行分析,对漫坝风险进行理论讲解,最终建立了漫坝风险分析理论,这一理论是建立在土坝对风浪和洪水联合作用下进行抵抗的基础之上的.     

Risk analysis for earth dam overtopping

In this paper, a model of overtopping risk under the joint effects of floods and wind waves, which is based on risk analysis theory and takes into account the uncertainties of floods, wind waves, reservoir capacity and discharge capacity of the spillway, is proposed and applied to the Chengbihe Reservoir in Baise City in Guangxi Zhuang Autonomous Region. The simulated results indicate that the flood control limiting level can be raised by 0.40 m under the condition that the reservoir overtopping risk is controlled within a mean variance of 5×10-6. As a result, the reservoir storage will increase to 16 million m3 and electrical energy generation and other functions of the reservoir will also increase greatly.     

堤防漫顶可靠性分析模型及其应用

针对防洪工程规划中防洪标准或堤顶高程的确定,按照风险管理方法建立了堤防的漫顶可靠性分析模型。该模型考虑了水文、水力和风等风险源的随机性。结合实例,分析了堤防的漫顶可靠度、设计洪水标准、堤顶高程、设计风速等关键指标之间的关系。成果对于今后在堤防工程规划设计中采用基于堤防可靠性的标准具有参考价值。     

特殊运行工况下水库预泄调度方式研究

因滁州市某水库特殊的实际运行工况,当遭遇较大洪水时,极易导致水库发生洪水漫顶现象,危害水库安全、降低水库防洪能力.针对这一问题,在充分考虑该水库特殊运行工况及调度约束条件的基础上,研究并提出在洪水到来前24 h,按一定预泄流量提前将水库水位从汛限水位降至某个水位,增加防洪库容;在洪水经过时,再根据批复的洪水调度方式进行...     

基于蒙特卡罗法的土石坝洪水漫顶风险率计算及其敏感性分析

为了减少土石坝因洪水漫顶造成溃坝所带来的损失,详细介绍了计算土石坝洪水漫顶风险率的蒙特卡罗法模型,分析了影响土石坝洪水漫顶的主要因素为洪水、风浪、水库运行调度方式和水库特性。针对这些因素进行洪水漫顶风险率的敏感性分析,并以南方某土石坝为例进行了实例研究。结果表明:洪峰流量均值和变差系数以及最大风速的均值对土石坝洪水漫顶风险率的影响较大,洪峰流量的偏态系数和风速的均方差的影响较小;水库自身特性及洪水到来前的水库初始水位的影响也比较大。该实例计算得到的洪水漫顶风险率经与相关工程实例分析计算成果比较,表明采用蒙特卡罗法计算洪水漫顶风险率是可信的。     

A quantitative model for danger degree evaluation of staged operation of earth dam reservoir in flood season and its application

Based on the natural disaster risk evaluation mode, a quantitative danger degree evaluation model was developed to evaluate the danger degree of earth dam reservoir staged operation in the flood season. A formula for the overtopping risk rate of the earth dam reservoir staged operation was established, with consideration of the joint effect of flood and wind waves in the flood sub-seasons with the Monte Carlo method, and the integrated overtopping risk rate for the whole flood season was obtained via the total probability approach. A composite normalized function was used to transform the dam overtopping risk rate into the danger degree, on a scale of 0–1. Danger degree gradating criteria were divided by four significant characteristic values of the dam overtopping rate, and corresponding guidelines for danger evaluation are explained in detail in this paper. Examples indicated that the dam overtopping danger degree of the Chengbihe Reservoir in China was 0.33–0.57, within the range of moderate danger level, and the flood-limiting water level (FLWL) can be adjusted to 185.00 m for the early and main flood seasons, and 185.00—187.50 m for the late flood season. The proposed quantitative model offers a theoretical basis for determination of the value of the danger degree of an earth dam reservoir under normal operation as well as the optimal scheduling scheme for the reservoir in each stage of the flood season.     

通过漫坝风险管理提高水利枢纽发电效益

运用漫坝风险分析理论,对紫坪铺水利枢纽漫坝风险进行了分析、计算,在确保水库漫坝风险小于10-6的前提下,提出汛限水位动态控制的建议。最终把汛限水位从850m抬高到855m,将使其多年平均发电量增加约1亿kW.h,从而提高了发电效益。     

清河水库防洪预报调度方式的研究

清河流域洪水达100年一遇时,若依现行泄流方式进行调洪,则将严重威胁工程安全。因此.选择了保持汛限水位不变,结合漫顶风险分析的可靠度分析成果,寻求一组新的可操作调度方式,通过综合比较,水库按新方式运行,发生标准以内的洪水时,水库及下游堤防安全系数更大。     

Risk and uncertainty analysis for dam overtopping – Case study: The Doroudzan Dam,Iran

There is a growing tendency to assess the safety levels of existing dams by using mathematical and statistical methods. In this study, the application of risk and uncertainty analysis to dam overtopping is presented for Doroudzan Reservoir located at the south part of Iran. The main objective of the overtopping analysis of dams is estimating the height of water in the reservoir under various inflows and comparing the computed results with the dam crest elevation. Hence, the main steps of this study include univariate flood frequency analysis of annual maximum inflows to estimate the peak flows in various return periods, generate inflow hydrographs based on the estimated peak flows, and route the hydrographs through the reservoir to compute the maximum height of the water in reservoir. In this study, the spillway discharge coefficient, quantile of peak flows, and initial water surface level are subject to uncertainty, and the Monte-Carlo simulation (MCS) and Latin hypercube sampling (LHS) are applied to perform the uncertainty analysis. In addition to inflows, the effect of different wind speeds on the probability of overtopping has been considered. The results demonstrated that both increasing water level and wind speed have significant impact on the risk of overflowing.