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《人民黄河》2019,(Z2)
水库大坝除险加固评价时采用专家打分的方法,往往忽略了不同专家间权威性的差异。本文提出了考虑专家权威性的病险水库加固评价专家主观权重的计算方法,从硬指标(包括资历、学术成果等)和软指标(包括评价实践经验、专业熟练程度和职业道德等)来衡量专家的权威性,并通过模糊优选理论确定各专家相对应的主观权重值,以权威优属度作为专家权威性的评价指标,增大权威性高的专家在水库大坝除险加固效果评价中的权重;通过归一化处理,得到参与加固效果评价的各位专家的权重向量;将专家主观权重计算方法与专家的客观权重计算方法配合使用,获得特定指标的专家综合权重,进而可对病险水库加固效果进行科学的评价。 相似文献
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目前病险水库的除险加固设计只偏重于工程治理措施,倾向于水库大坝工程的安全,未考虑除险加固设计方案对下游居民安全、社会经济、城镇交通等的风险以及对自然环境的影响。因此,基于风险分析的除险加固优化技术对于今后病险水库除险加固方案是有效和必要的。本文参考国外病险水库大坝安全和除险加固风险分析理论的最新进展,结合我国病险水库大坝和除险加固技术的特点,进行了除险加固方案与大坝风险关联分析与决策、除险加固方案评价指标分析和基于风险分析的除险加固方案优化技术的研究,提出了基于风险的病险水库除险加固方案的评价、分析和优化方法,为今后病险水库除险加固工作提供技术支撑。 相似文献
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除险加固效果评价是目前国内病险水利工程除险加固项目后评价中急需解决的关键问题。针对综合评价所需的指标体系和方法体系,从宏观定性评价、单一效能量化评价、综合评价指标体系、指标权重、评价等级划分及确定等方面,综述了病险水利工程除险加固效果评价的研究进展。认为今后应构建能兼顾病险水利工程除险加固治理效果通用性和特殊性的综合评价指标体系,建立除险加固效果评语集、评价指标权重和等级隶属度三方面的云模型,并强化除险加固效果评价中的可持续发展效应。 相似文献
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病险水闸除险加固效果评价是一个复杂的系统工程,其评价指标信息、权重和评语集均具有模糊性与不确定性。为了对病险水闸除险加固效果进行综合评价,根据《中央政府投资项目后评价管理办法》,建立了包含5个一级评价指标和21个二级评价指标的综合评价指标体系,拟定了百分制下的评价等级划分标准。在此基础上,引入云模型理论,建立了权重云模型、评语集云模型和评价指标信息云模型,进而利用云模型的数字特征来量化评价过程中不确定性的传播效应和评价结果的可信性及稳定性。太浦闸实例分析验证了此方法的可行性与实用性,结果表明权重的不确定性对评价结果有较大影响,该闸除险加固效果处于“效果极佳”等级,与实际情况相符。提出的评价指标体系和云模型评价方法可用于其他病险水利工程的除险加固效果评价中。 相似文献
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大坝除险加固效果评价指标包括时效性指标和非时效性指标两类,时效性指标的量化是进行大坝除险加固效果定量评价的关键。针对现有大坝除险加固评价体系中时效性指标量化理论较为缺失的问题,基于无量纲化的定量时效性指标,研究了大坝性态变化以及指标等级变化对时效性指标评价的影响,推导了安全度和等级提升系数的公式,进而建立了时效性指标量化模型。以江西某水库除险加固为例,分析除险加固前、后各时效性指标的变化情况,并对模型的合理性进行了验证。结果表明,应用本文建立的大坝除险加固时效性指标量化模型可合理评价除险加固过程中的时效性指标。 相似文献
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针对目前除险加固后病险水库康复度难以准确评价的问题,构建了两层评价指标体系,结合模糊灰色聚类和组合赋权法对病险水库康复度进行量化评价。基于熵权法和层次分析法分别计算各康复类型评价指标的主、客观权重,采用组合赋权法将主、客观权重进行组合,得到能反映主客观影响的组合权重;采用灰色聚类法评价水库各康复类型的康复度,依据病险水库各康复类型聚类系数及组合权重创建综合评价的模糊判断矩阵,依据模糊判断矩阵由熵权法和层次分析法求出各康复类型的权重后采用组合赋权法进行组合,最终采用模糊综合评价法评估病险水库除险加固后的康复度。将该方法用于3座病险水库康复度评价,评价结果与水库除险加固实际情况及验收结论吻合,表明该方法具有一定的工程应用价值。 相似文献
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根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。 相似文献
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The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects. 相似文献
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Samples were taken year-round at eleven sites along the altitudinal profile (2900-1400 m a.s.l.) of the Gunnison River, a 329 km tributary of the Colorado River, to document the distribution of the Plecoptera and to evaluate responses to hypolimnial-release dams in the headwaters and middle reaches. Twenty-two species were present, with the greatest species richness occurring in an unregulated segment upstream of the middle reach dams; average nymphal biomass over the study period (175 organisms, 395 mg dry mass m?2) was also greatest in this segment. Only four species (58 organisms, 48 mg m?2) were present in the tailwaters of the headwater dam and values were greatly reduced (nine species; 35 organisms, 180 mg m?2) below the middle reach dams. The stonefly community recovered ca. 80 km downstream from the last dam (15 species; 244 organisms, 250 mg m?2), apparently in response to natural resetting of environmental conditions corresponding to those above the middle reach dams. At the most downstream site (11) only four species (four organisms, 16 mg m?2) were present. The observed distributional pattern is a classic serial discontinuity in response to hypolimnial stream regulation in a temperate latitude river. 相似文献
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In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed
in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash
and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers
of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional
components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect
dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system,
configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants
of dry ash utilization and the advantages of producing of size-separated particles are considered.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed. 相似文献