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桥梁深水基础与钢围堰施工是一个经久不衰的研究课题,随着道路与桥梁工程的发展,钢围堰施工技术得到了很大的提升。在钢围堰施工技术及施工工艺日趋完善的今天,如何优化工艺和加快工序转换成为研究的.一个重要方向。云南八大河特大桥12#、13#主墩位于南.盘江水域之中,基础采用2.0根直径25m钻孔.灌注桩,呈行列式布置,桩纵、横向间距均为55m,承台尺寸顺桥向为209m,横桥向为264m,高5m,为深水基础施工。通过了解南盘江水文情况,掌握水位变化规律,利用库区水位高低落差周期,在枯水期对主墩承台区域进行提前清淤以此减少钢围堰正式下放后工程量;钢围堰拼装及下放时,采取分节段现场拼装、8台200t连续千斤顶整体下放工艺有效提高了施工效率。通过此次库区高落差水位钢围堰施工案例,为后续类似施工项目提供了宝贵经验。 相似文献
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为解决现有船舶结构初步设计过程中精细化程度不足的问题,开展基于多工况拓扑优化算法的归一化数学模型研究及其典型应用探索。本文将多工况拓扑优化算法引入到船舶结构初步设计中,提出了基于k方法的权因子确定方法,引入全局化应力约束条件,建立考虑应力约束函数的多目标拓扑优化数学模型,并对某高双层底实肋板结构进行多工况静力学拓扑优化研究。结果表明,最终构型能够满足应力应变等基本约束条件且具备较好的工艺性。相关研究成果为运用拓扑优化方法进行船舶结构初步设计提供一条切实可行的途径,具有一定的理论与工程应用价值。 相似文献
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为确保桥梁施工期间桥区通航安全,分析大型钢围堰设置对航道水流条件带来的影响。以重庆某大桥钢围堰设置为例,以流体质量守恒方程和雷诺时均方程为理论基础,基于Fluent有限元软件采用二阶迎风算法和格林梯度法,数值模拟钢围堰设置河段桥梁轴线方向和垂直桥梁轴线方向的断面流速。通过钢围堰设置前后各断面流速变化的比较与分析,得出钢围堰设置对航道水流条件产生的影响。研究结论表明:1)在垂直桥梁轴线方向上,从钢围堰前端起沿水流方向0.4Bs~3.3Bs(Bs为钢围堰的宽度)处流速增量最为明显。2)在桥梁轴线方向上A区域断面水流流速剧增且钢围堰设置造成的紊流对水流影响的宽度约为3.7Bs。3)钢围堰尾部形成了约1.3倍钢围堰长、1.5倍钢围堰宽的涡街。4)分析得出的钢围堰设置期间航道水流条件变化特征对维护航道通航安全有重要意义。 相似文献
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针对汉江某航电枢纽土石围堰汛期导截流的问题,采用数值模拟方法对工程方案进行优化,研究戗堤进占过程的水力特性以及截流对岸坡的冲刷影响,合理确定水下抛石料粒径。结果表明:1)通过对比实测数据,验证了该数值模拟方法的可靠性。2)成功预测了一期围堰挡水能力,预测水位精度高达0.5 m。3)二期上游围堰采用双向立堵法,减少了截流对岸坡的冲刷。同时预测的龙口流速及抛石粒径能够满足施工要求,为施工组织设计提供了科学依据。研究成果已成功运用于该项目实际施工中,并保证了该工程汛期一次实现成功截流。 相似文献
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价值观是指人们对价值的性质标准、构成和评价的基本看法和态度,是指导人的行为的一系列基本准则和信条。构建海事核心价值观是时代发展的要求,更是海事自身发展的需要。 相似文献
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This chapter presents a summary of the findings of the workshop on ‘Analytical and Institutional Methods and Frameworks’. The paper discusses the nature of the analytical methods used in the papers presented and the purposes for which they were employed, which were generally to either assist in the planning and operation of public transport or to monitor the efficiency and effectiveness of transport services. Subsequent sections examine issues related to data collection and management, and the more general issue of institutional arrangements. Policy and research agendas needed to support further consideration of the subject are then identified. 相似文献
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介绍青藏高原多年冻土的冻融特性,并结合我局在青藏铁路十二标段的具体施工,分析了冻土的冻融特性及具体防止措施. 相似文献
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Geoffrey Wood 《Maritime Policy and Management》2004,31(2):157-171
This paper explores the current state of coastal and inland shipping in Tanzania. It provides an overview of the state of ports and shipping in Tanzania, and the reasons underlying the present crisis of competitiveness in terms of both global pressures and national and regional dynamics. Problems of competitiveness are at least partially due to under-investment, management failures, skills shortfalls and difficulties in interfacing with the railway network. Less easy to resolve structural problems include the great imbalance between imports and exports, heightened regional competition and ongoing political instability in the Great Lakes region. 相似文献
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风量与风压的简易测量及应用 总被引:2,自引:0,他引:2
锅炉正常燃烧必须有充足的风量,当锅炉鼓风或引风不足将导致锅炉效果恶化,锅炉出力、热效应率明显下降。结合工程实例,介绍结托管简揭测试鼓、引风系统各部分风压、风量,帮助判断分析工程实际问题的简便方法。 相似文献
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Elizabeth A. Wilman 《Coastal management》2013,41(3):211-230
As the controversy over Outer Continental Shelf (OCS) oil and gas leasing continues, with environmentalists and fishermen seeking to block or delay leasing decisions that they think will adversely affect their interests, the need for better estimates of the environmental costs associated with OCS development becomes increasingly apparent. Although high degrees of precision in such estimates may never be economic, let alone feasible, better knowledge would reduce the uncertainty surrounding the magnitude of such costs, and would make it easier to come to grips with the problem and reduce, if not resolve, the controversy. 相似文献