Cost-effective Private Dam Safety Assurance Policy and Spillway Design/Review

Owner-obligationexists under common law to take reasonable care of dams according to current prevailing standards. However, this obligation may not be met in places where there is an absence of private dam safety assurance policy, which creates the possibility of placing the public at risk. To explore the potential seriousness of this problem, a case study has been conducted in the policy-absent state of South Australia where 11 hazardous private reservoirs have been investigated for spillway adequacy in line with state-of-the-art practice. Common high levels of deficiency have been discovered. Extended flood studies of hypotheticaldams placed on the same catchments, bearing a wide range of spillway capacities and reservoir conditions, have then been conducted. Appropriate analysis has led to the derivation of regionalized relationships based on simple hydrological/hydraulicvariables, for predicting reservoir flood capability as either 1/AEP or %PMF. The relationships have been utilized to develop a simple and cost-effective flood capability design/review procedure for reservoirs on small catchments which is compatible with any design flood standards. The paper also provides guidelines and criteria, based on international experience and practice, for government to readily explore an 'appropriate' private dam safety assurance policy for any jurisdiction. The guidelines, incorporating the cost-effective flood capability design/review procedure, aim to minimize review costs to private owners and ensure an acceptable level of private dam safety management.     

Attitudes and Policy Responses to Australian Farm Dam Safety Threats: Comparative Lessons for Water Resources Managers

The safety of medium- and large-scale dams is addressed in many countries, but limited attention is paid to problems associated with smaller farm dams, particularly potential cumulative threats posed in larger catchments. Farmers in Australia often overlook the common law obligation to review and design dams in line with current standards. The result is downstream communities, property and environment placed at risk. This paper demonstrates the significance of this problem with case studies undertaken in policy-absent South Australia, policy-driven Victoria and policy-strong New South Wales, including empirical evidence on attitudes and responses of landholders and key policy actors. This demonstrates need for supervision of small dams. Tasmania is included as a case study as it represents a policy-model state on how this can be best achieved in line with international best-practice. The four cases provide useful comparative lessons. Policy guidelines applicable to any jurisdiction are included; their application is illustrated with the case studies. The paper considers the policy implications of these lessons for Australia in particular and the world in general.     

A Farmer-Friendly Dam Safety Evaluation Procedure As A Key Part of Modern Australian Water Laws

Abstract

The largest dams are generally built and managed by Governments; individual owners build small dams. Over time, many dam safety aspects have changed, such as population distributions, meteorological information, engineering methods and design standards, together with the condition of the dams, raising serious doubts about dam adequacy. For the larger dams response has been to spend vast amounts on remedial works. Unfortunately, only a few countries have developed mature safety assurance schemes for smaller dams: these are comparatively reviewed here identifying elements of “minimum” and “best” practice, and providing policy models and guidelines of “appropriate” practice for varying circumstances. Farmers often overlook common law obligation to review/design dams in line with current standards because of high engineering consulting costs. A cost-effective spillway design/review procedure that is applicable to South Eastern Australia, but is transferable to any other region world-wide, is also reported here: this procedure is integrated with the policy models and guidelines, aiming to minimize cost burdens to dam owners, encourage better dam safety management, and provide an acceptable level of safety assurance to downstream communities.     

印尼某堆石坝坝体-溢洪道结构接触特性

印尼JATIGEDE黏土心墙堆石坝将溢洪道直接设置在由散粒体构成的坝体上,左右边墙直接与堆石坝黏土心墙相接,形成了国内外罕见的堆石坝坝型,坝体、溢洪道及坝体-溢洪道接触部位受力特性直接影响到工程的长期运行稳定性。基于三维非线性有限元法,在坝体渗流场分析的基础上,系统研究正常运行工况下堆石坝坝体、溢洪道结构以及坝体-溢洪道接触部位的应力、变形规律。结果表明:堆石坝坝体与溢洪道接触部位应力应变规律与常规心墙堆石坝有显著差异;坝体与溢洪道接触部位坝体土安全系数较低,应力集中明显,应力水平较高;坝体沉降、渗透比降、应力水平等均满足设计控制标准,大坝结构设计方案合理。     

拱坝表孔设计及消能问题的探讨

建于狭窄河谷的拱坝一般采用表孔溢流,溢流堰包括圆心点上游头部曲线、堰面曲线及反弧曲线三部分.设计参数有定型水头H<,s>、反弧半径R、反弧角θ<,1>、挑角θ<,2>等.结合已投入运行的几个工程实例对这些参数的设计取值进行研究,将理论计算结果与运行实测结果进行了比较,探讨了各参数的取值范围,对挑流公式、跌流公式的适用条件进行了初步分析.     

天生桥一级水电站大坝和溢洪道工程合同管理

阐述了监理工程师在大坝和溢洪道工程合同执行中进行的工作，从有利工程顺利进展做好工程投资控制的角度，对有待解决的问题，完善和加强合同管理进行了研究。     

大朝山水电站坝体溢洪表孔采用台阶溢流坝面简介

大朝山水电站拦河坝溢洪表孔采用宽尾墩| 戽式消力池联合消能工，设计单位经多年潜心研究。在百米级碾压混凝土坝、大单宽流量条件下采用台阶式溢流坝面，经第一次原型观测试验，验证了模型试验结论，并发现了水舌下缘与台阶接触带底流速沿程不变、水舌底部掺气浓度沿程增加的现象，这对今后同类工程设计提供了极具参考价值的工程应用实例。文章简略介绍了表孔溢流面结构变更的提出、模型、原型试验结果，以及采用台阶溢流坝面所带来的效益等。     

堰塞坝溃决模拟研究综述与展望

堰塞坝几何形态、粒径级配和库容决定了其溃决机理的复杂性,而溃决过程的精细模拟和峰值流量的准确预测是应急处置的基础和关键.堰塞坝溃决过程与模拟技术是面向国家防灾减灾重大需求的前沿热点问题.在系统梳理国内外试验和数值模拟研究进展的基础上,指出以往试验研究坝体尺度小,足够大的库容基本未模拟,难以显示最终溃口形态;数学模型假设...     

二滩拱坝表孔、中孔初期运行情况及评价

二滩水电站拱坝的表孔和中孔是整个枢纽的主要泄洪建筑物。文中结合1998年和1999年两次度汛泄洪及1999年10月的泄洪消能水力学原型观测试验,简述了表孔和中孔的设计要点,并对表孔和中孔的初期泄洪运行情况进行了安全评价。     

澳大利亚大坝风险评价的法规与实践

澳大利亚的大坝安全管理和风险评价方面处于国际领先水平．根据水利部2002年初群坝风险分析培训考察的结果,介绍了澳大利亚在大坝风险评价方面的法规与指南,特别是指南中要求的几项重要工作,如风险人口分析、溃坝影响评价、风险准则、群坝风险分析等．以Ross River坝为例,系统地介绍了风险评价技术的实际应用．风险评价技术是大坝安全管理的发展方向,应尽快引进推广．     

牛路岭水电站大坝空腹拱顶和溢流面反弧段的结构可靠性分析

采用钢筋混凝土非线性随机有限元法，对牛路岭水电站空腹重力坝的空腹拱顶和溢流面反弧段进行了结构受力和可靠性分析计算，给出了在主要运行工况下，上述部位的开裂和承载力可靠指标及相应的失效概率。     

平班水电站溢流坝碾压及变态混凝土设计与施工质量控制

平班水电站溢流坝采用碾压及变态混凝土施工技术,施工工期短、强度大,通过碾压及变态混凝土配合比设计试验及施工质量控制,改进施工工艺方法,取得良好的施工效果及质量效果.     

基于超级电容储能的风电场功率调节系统建模与控制

随着风电装机容量的不断提高,风电输出功率的波动性给电网带来的不利影响越来越得到重视。文中介绍一种基于超级电容储能的风电场功率调节系统,利用超级电容器组作为储能元件,平抑风电场有功、无功功率波动,维持风电场输出端电压,降低风电场对电网电能质量的影响。基于功率调节系统的结构特点和工作原理,提出了一种网级控制、超级电容能量管理和变流器控制相结合的控制策略,并建立了变流器的动态小信号模型,进行了环路控制器设计。利用仿真软件PSCAD/EMTDC对系统的控制策略进行了仿真分析,仿真结果验证了该装置具有良好的运行性能。     

漫湾重力坝抗震试验研究

针对漫湾溢流式厂房重力坝进行了动力模型试验，全面分析了大坝及其厂房的动力特性。由于某些模态之间耦合比较严重，为了得到纯模态，利用频响函数虚部进行识别。在８度地震作用下，漫湾重力坝能满足抗震稳定的要求，除上游坝踵和闸墩下游底部应力较大、应适当提高混凝土标号外，其余部分都符合水工建筑物抗震设计规范要求。     

某水电站溢洪道牛腿与大坝碾压混凝土整体上升施工方案

杨家园水电站位于贵州省习水县二郎乡,地处赤水河一级支流桐梓河下游河段。水电站大坝为碾压混凝土椭圆双曲拱坝,最大坝高66 m,坝底厚18.5 m,坝顶厚5 m,厚高比0.28,坝顶中心线弧长150.8 m,碾压混凝土浇筑量约7.2万m3。文章介绍了杨家园水电站碾压混凝土拱坝在施工过程中,提出的针对溢洪道牛腿部位与大坝整体上升的施工方案,达到了缩短工程工期、保证施工安全的效果。     

小湾工程增大坝身泄量减少一条泄洪洞方案的试验研究

本文论述了小湾水电站减少一条泄洪洞的泄洪消能布置型式的选择，认为减少一条泄洪洞是可行的，采用三套泄洪设施和优化确定的水垫塘型式及二道坝位置是适合的。     

中小型拱坝表孔大流量泄洪消能建筑物体形研究

依据圆满贯工程水工水力学模型试验资料,对中小型拱坝表孔大流量泄洪建筑物体形问题进行研究,提出了一种复合消能工体形与设计思路,即采用宽尾墩窄缝纵向水舌与连续鼻坎横向扩散的综合形式,可使水舌在纵向与横向实现全范围的扩散,充分利用消能空间与水体,既适应了不同流量洪水泄洪的要求,又使消能率得到大幅度提高,大流量泄洪冲坑深度可减小28%.     

玄庙观水库拱坝整体水工模型试验研究

玄庙观枢纽工程为双曲拱坝,其特点为窄河床、陡边坡、坝顶溢洪道较宽,泄流时易造成对岸边的冲刷。主要论述在综合考虑闸前流态、水舌挑距及坝下冲刷情况前提下的合理闸门运用方式,根据下游冲刷效果提出对闸墩及消能工进行修改的建议,为类似工程设计提供参考。提出的宣泄不同标准洪水的闸门运用方式,可供管理运行单位参考。     

三峡溢流坝段动力特性及动力反应分析

本文应用有限元的数学模型,计算了三峡溢流坝——库水——基础系统的动力特性,并用反应谱理论和时程分析计算了坝体动力反应。分析结果表明:该坝型有利于提高抗震能力,地震对坝的稳定和应力状况均能满足设防要求。最后还提出了进一步改善坝的动态特性的建议。     

双曲拱坝溢流表孔分流齿的水力特性与设计原则

结合二滩双曲拱坝,简要地介绍了拱坝坝顶滥流表孔设置分流齿的选型、布置及其消能、空化、通气减蚀、水流脉动荷载和泄洪振动等水力特性。研究表明,在俯角跌坎式表孔上设分流齿可以提高表孔的泄洪消能效果。