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砂土中掺入泥浆、膨润土、水泥可降低砂土的渗透系数,通过室内配合比试验,可得到满足密封墙渗透性能要求的配合比。在成层土平均渗透系数理论的基础上,建立砂土密封墙渗透系数理论。混合土的渗透系数由细粒土的渗透系数及厚度控制,膨润土通过吸水膨胀作用,主要改变混合物的渗透系数;水泥与土中孔隙水发生水化反应,主要改变细粒土的渗透系数。结果表明,根据砂土密封墙渗透系数理论可计算出混合土的细粒土厚度、掺入膨润土后混合土中混合物的渗透系数、掺入水泥后混合土中细粒土渗透系数。 相似文献
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桶式基础结构是一种轻型结构,适用于承载力低的淤泥质地基,其稳定计算依靠桶体与土共同作用抵抗外荷载,因此土压力是桶式基础结构稳定计算的核心内容,其分布规律和大小对计算结果起到控制作用。通过模型试验结果验证了有限元模型参数取值的合理性,从而采用有限元数值模拟的方法,探讨了波浪荷载和回填荷载作用下,不同土层产生的主被动土压力分布规律,得到位移形式对土压力大小的影响、不同土层之间相互作用引起土压力分布形态的变化、理论公式的修正系数以及施工顺序对土压力分布形态的影响。研究成果明确了不同荷载作用和土层分布对土压力的影响规律,修正了主被动土压力的传统计算公式,为桶式基础结构稳定计算奠定了一定的基础。 相似文献
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黄骅港地区海底表层存在一层饱和软土,对工程结构的设计及稳定性分析有重要影响。为准确确定该层土的十字板剪切指标,本文引入灰色关联分析方法,以黄骅港散货港区矿石码头工程数据为例,通过计算该土层十字板强度指标与各主要物理性指标的灰色关联度,可知十字板强度值与天然重度指标关系最为密切,且地基处理的不均匀性对十字板强度影响较大。 相似文献
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天津滨海新区中央大道海河沉管隧道的沉管管段需要在干坞内预制完成,干坞内土体在卸荷状态下的承载与变形特性将发生变化,影响干坞基底承载力。根据干坞开挖的卸荷应力路径,通过室内试验,对卸荷状态下干坞基底土承载与变形特性进行试验研究。得出了不同深度土层卸荷后强度的变化情况,同时对卸荷影响深度进行了试验研究。由于开挖对不同土层不同深度土体强度影响不同,很难用传统的极限承载力公式计算基底承载力,根据试验得出的卸荷后土体强度指标,对干坞基底承载和变形特性进行了有限元计算,根据计算结果确定干坞基底在沉管管段荷载作用下的稳定性和安全系数,为以后的干坞设计提供依据。 相似文献
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利用有限元软件ANSYS对双层土中超长桩水平承载性能进行模拟,得到桩土相互作用下土抗力及超长桩桩身弯矩及侧移。分析桩侧竖向摩阻力、环向摩阻力和法向土抗力沿桩身的分布和对承载力的贡献以及超长桩水平承载性状随荷载、土层相对模量比、桩长径比的变化规律。结果表明:桩侧竖向摩阻力、环向摩阻力、法向土反力沿桩环向呈不同的曲线分布规律,沿深度呈递减趋势,桩顶最大;在不同分层情况下桩身弯矩和侧移量随着土层弹性模量比的增大而减小;水平受荷超长桩存在有效长度和最优长径比;沿桩身存在反弯点和位移零点。 相似文献
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为明确天津碱渣土的力学性质和基本参数,通过固结、直剪(慢剪、固结快剪以及快剪)、颗粒级配分析、液塑限联合测定等室内土工试验,对碱渣土试样压缩性、比重、强度参数、密度、渗透系数、颗粒级配、液塑限等进行测定。试验结果表明,碱渣土的孔隙比为4.44、含水率达198.1%、压缩模量为1.59 MPa、渗透系数为1.40×10~(-5) cm/s以及较高的液、塑限。相比具有相近孔隙比、含水率等物理力学指标的黏性土和淤泥土,碱渣土的抗剪强度高、压缩性低且渗透性好。通过室内土工试验测得的碱渣土参数准确,可为数值仿真和现场试验等提供数据支持。 相似文献
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《船舶与海洋工程学报》2014,(2)
正In the paper"Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar,India"in Vol.12,No.4,Page:509,References were lost,and the two authors’biographies were identical.The correct text is shown below.We apologize to the authors and our readers for any inconvenience caused by the errors. 相似文献
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《船舶与海洋工程学报》2014,(4)
正St.John's,Newfoundland,Canada,May 31-June 5,2015 OMAE2015 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to: meet and present advances in technology and its scientific support; 相似文献
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联合作战计划和执行系统 总被引:2,自引:1,他引:1
全球指挥控制系统(GCCS)实施当前美国海军网络中心战信息基础设施的联合计划网络。联合作战计划和执行系统(JOPES)支持GCCS实现联合计划。JOPES有两类计划:时间不限的精密预案计划生成作战计划、方案计划或职能计划;时间敏感的危机行动计划生成作战命令或战役方案。前者在和平时期创建的作战计划是后者的计划基础,加速应付危机的能力。 相似文献
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In terms of equal sailing distances, where is the inflexion when ships depart from ports in the Asian Continent to New York via Suez and/or Panama?
The answer is China South Port Group (Hong Kong, Shenzhen and Guangzhou). 相似文献
The answer is China South Port Group (Hong Kong, Shenzhen and Guangzhou). 相似文献
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Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form. 相似文献
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桥梁防撞设施物理模型试验 总被引:1,自引:0,他引:1
物理模型试验是预报防撞设施所受撞击力及优化设计方案的主要方法之一。结合杭州湾大桥柔性防撞设施及东海大桥独立式防撞体设计方案,阐述了船—防撞体撞击试验的基本原理、方法、试验方案及相关试验结果。提出了柔性防撞系统的优化方案。试验结果表明,该方案经济有效,可供预报类似桥梁防撞设施撞击力时参考。 相似文献
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印尼某电厂项目码头水工建筑物包括码头、防波堤和护岸等主要组成部分。在该项目水工建筑物的设计过程中,综合考虑当地的自然条件、施工能力和材料来源等因素,不断优化结构选型和结构断面。根据不同使用要求,护岸分别采用直立式和斜坡式2种结构型式,推荐的设计方案节省投资、施工方便,可供同类工程设计参考。 相似文献
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Gunnar Alexandersson Staffan Hultén Frode Longva 《Research in Transportation Economics》2010,29(1):212-218
Despite the many socio-economic similarities between Sweden and Norway, differences in jurisdiction, organisation, cooperation, and financing of long-distance passenger train and coach services have led to the development of four distinctively different ways of serving the markets. This paper describes how the train and coach markets have developed in the two countries, with emphasis on regulatory and industrial structure and a couple of performance variables.Looking at passenger rail, both countries separated infrastructure from operation over a decade ago. However, while Norwegian rail is characterised by an almost monopoly supplier, rail services in Sweden are partly decentralised to the responsibility of county authorities and are widely subjected to competitive tendering. The rest of the network is about to be opened up for on-the-track competition. Swedish Rail (SJ) has spent the last decades consolidating its core business (passenger rail) and sold out its other businesses. In contrast, the Norwegian state rail (NSB) has expanded its business to become a major bus operator and property owner, with extensions also into the Swedish market.The coach industry was more recently deregulated in both countries. The Swedish coach market is dominated by privately owned companies operating services to and from Stockholm. In Norway, state-owned NSB is a major coach operator on medium distance routes, and is also the largest partner of Nor-Way Bussekspress which totally dominates long-distance coach services. Further, the Norwegian coach market is characterised by cross-ownership and cooperation which has enabled an extensive route network which covers most of Norway.We find distinct differences in achievements in the two modes and in the two countries. Swedish rail services have succeeded in winning market shares and in renewing and developing both infrastructure and service levels to a greater extent than the Norwegian model. On the other hand, the Norwegian coach market seems to be more developed and efficient compared to its Swedish counterpart.The paper concludes with a discussion on the possible links between the different approaches and the performance observed, with the aim to stimulate further and more detailed research on some important issues. 相似文献