摘要：Buckling of submarine pipelines under thermal stress is one of the most important problems to be considered in pipeline design. And pipeline with initial imperfections will easily undergo failure due to global buckling under thermal stress and internal pressure. Therefore, it is vitally important to study the global buckling of the submarine pipeline with initial imperfections. On the basis of the characteristics of the initial imperfections, the global lateral buckling of submarine pipelines was analyzed. Based on the deduced analytical solutions for the global lateral buckling, effects of temperature difference and properties of foundation soil on pipeline buckling were analyzed. The results show that the snap buckling is predominantly governed by the amplitude value of initial imperfection; the triggering temperature difference of Mode I for pipelines with initial imperfections is higher than that of Mode I1; a pipeline with a larger friction coefficient is safer than that with a smaller one; pipelines with larger initial imperfections are safer than those with smaller ones.

摘要：This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.

摘要：The hydraulic characteristics of artificial waterfalls constitute an important research area for both academia and industry. As yet, the hydraulic parameters used in the hydraulic design of landscape waterfalls are not well understood for use in qualitative and quantitative analyses. Due to their complicated shapes and appearances, it remains a challenging problem to design or simulate realistic waterfall scenes. In this paper, we present a hybrid model and an efficient numerical method for simulating the hydraulic characteristics of waterfalls and investigate the critical flow in waterfall design and the adherent flow phenomenon. We fit empirical equations to predict the size and shape of different waterfall flow patterns to provide a basis for the design and construction of waterscapes in the real world. We then apply our work to an artificial waterfall in Kraal Jiang River and the results demonstrate that our model achieves desirable control qualities and good agreement in a real-world application. © 2017, Tianjin University and Springer-Verlag Berlin Heidelberg.

摘要：Three- and four-bucket offshore wind power foundations with a new form of force-transferring structure are proposed in this paper, and the integrated finite element model of foundation-soil-transition structure is established by using ABAQUS. The carrying capacity of the proposed foundations is studied under vertical load, horizontal load and bending moment. It can be seen that the vertical bearing capacity of multi-bucket foundation can be roughly estimated by the vertical bearing capacity of single-bucket; the horizontal bearing capacity of the three-bucket foundation scheme is controlled by displacement, while that of the four-bucket foundation scheme is controlled by the internal forces of soils. Moreover, the carrying capacity is provided by the overall structure formed by multi-bucket before soil failure. Compared with the conventional single-bucket foundation, there are mainly tension and pressure that are applied to the multi-bucket foundation, so that the carrying capacity of the foundation can be fully utilized. The probability of soil failure can be well reduced with the proposed multi-bucket foundation, and the stress transmission of force-transferring structure is more consistent through steel beams with variable cross-section.

摘要：Time, cost, and quality are three key control factors in rockfill dam construction, and the tradeoff among them is important. Research has focused on the construction time-cost-quality tradeoff for the planning or design phase, built on static empirical data. However, due to its intrinsic uncertainties, rockfill dam construction is a dynamic process which requires the tradeoffto adjust dynamically to changes in construction conditions. In this study, a dynamic time-cost-quality tradeoff （DTCQT） method is proposed to balance time, cost, and quality at any stage of the construction process. A time-cost-quality tradeoff model is established that considers time cost and quality cost. Time, cost, and quality are dynamically estimated based on real-time monitoring. The analytic hierarchy process （AHP） method is applied to quantify the decision preferences among time, cost, and quality as objective weights. In addition, an improved non-dominated sorting genetic algorithm （NSGA-II） coupled with the technique for order preference by similarity to ideal solution （TOPSIS） method is used to search for the optimal compromise solution. A case study project is analyzed to demonstrate the applicability of the method, and the efficiency of the proposed optimization method is compared with that of the linear weighted sum （LWS） and NSGA-II.

摘要：目的:工程规范中采取保守设计方法导致含有埋深的复合地基的承载力被严重低估。本文基于设计表格的方法展示水泥搅拌站复合地基的承载力系数(N_c、N_q和N_γ),分析埋深存在时的3种破坏模式,探讨承载力系数N_q和破坏模式随着各类因素(桩长、置换率和埋置深度)变化的原因。创新点:1.确定简化的均质化水泥搅拌桩加固地基模型;2.建立非连续布局优化法(DLO)模型,计算工程实用设计表格;3.分析极限承载力系数N_q、破坏模式和各类影响因素的内在关联。方法:1.通过等效强度法确定合理的均质化数值计算模型,并与群桩模型和前人研究进行对比验证(图4和表1);2.通过极限分析上限解结合非连续布局优化法,进行大量计算,建立极限承载力系数的设计表格(图6~8)。结论:1.对于无埋深工况,承载力系数N_c随着置换率的增长而增大,直到某一临界值,此时发生实体基础破坏。2.在置换率较低时,承载力系数N_γ随着置换率的增长而减小,因为此时加固区内的等效内摩擦角减小。3.埋置深度对承载力和破坏模式产生复杂影响;当破坏模式从实体基础转化为复合型破坏时,N_q增长;随着桩长进一步增加,破坏面通过加固区内部时,N_q在减小之后保持不变。

摘要：Cost-effective floating wind turbines with efficient installations are highly desired in deep waters(>50 m).This paper presents a submerged floating offshore wind turbines(SFOWT)concept for intermediate water depths(50-200 m).The performance of SFOWTs can be improved through a judicious choice of configuration,pretension,and mooring line *** SFOWTs with different configurations and a similar mass,named Cyl-4,Cub-4,Cyl-3,and Hex-3,were designed and *** responses of the four SFOWTs were predicted under operational condition and extreme *** results show that the four SFOWTs exhibited good performance under both *** effect of platform configurations on power output was negligible under the operational *** the extreme condition,among the four SFOWTs,the mean bending moments at the tower base were very close,while the maximum values differed by up to 21.5%,due to the *** effect of wind-wave misalignment under the extreme condition was further *** general,the motion performances of the four-pontoon SFOWTs,Cyl-4 and Cub-4,were superior to those of the three-pontoon SFOWTs,Cyl-3 and *** studies of the mooring system were carried out on Cub-4 with different mooring line pretensions and four mooring *** optimized Cub-4 could reduce the maximum motion responses in the surge,heave,and yaw by 97.7%,91.5%,and 98.7%,respectively.

摘要：目的:输水管道的驼峰气阻是指由于管路高峰位置的滞气作用使气体不断聚积在峰顶附近、产生的气体阻碍水流的局部水力现象。它能够导致管路过水断面减小、输水能耗增加、输送效率降低和管路压力振荡等后果,严重威胁海底管道输水的稳定性和安全性。本文旨在分析滞留气团在供水管道中的力学平衡、能量损失、移动和溢出机理,研究水流流速对气团的推移特性,提出预测和消除驼峰气阻的方法,使输水管道免受驼峰气阻的危害,提高输水管道的供水效率。创新点:1.设计了具有连续坡角变化的圆弧形驼峰管道实验,该实验可以定量模拟气团体积和平衡角度;2.建立了驼峰气阻的水头损失经验公式和恒定流情况下驼峰气阻的管道坡角和流速的对应关系式,可用于预测和消除驼峰气阻的危害。方法:1.通过驼峰气团的受力特性分析,获得满足量纲和谐的力学平衡方程;2.采用试验观察和测试获得有无气泡情况下的水头损失和平衡状态下的坡角,通过等价球体方法对测试数据进行无量纲拟合,获得气阻的水头损失方程系数,并通过流速和平衡坡角建立恒定流情况下的临界平衡方程;3.基于试验拟合获得临界平衡方程,建立预测和评估气阻的准则系数,并提出消除气阻的水流临界流速。结论:1.当管路流速较小时,供水管路的驼峰顶端可能滞留和聚集气体,形成驼峰气阻;气体体积越大对水流阻碍越明显,可能造成的水头损失也越大;2.利用等价球体法可以极大地简化驼峰气阻的形状,并良好地模拟气阻的平衡特性和阻力特性;3.管道流速是影响驼峰气阻临界平衡位置的最重要因素,通过减小管道起伏的坡角或增加水流流速可以防止和消除驼峰气阻的危害。

摘要：In this paper,the northern mountainous area of Fuzhou City which is an ungauged basin has been taken for example to discuss the method of design flood calculation by means of combining the DEM(digital elevation model) and the Xin'anjiang Model(three components).The problem of estimating the parameters of the runoff model has been solved by using the parameters of the reference *** the conflux calculation,the isochrones are obtained by DEM which helps to avoid the cumbersome work of drawing them on the *** the establishment of the digital elevation model throughout the country,it is practically significant to use it in the hydrological estimation.

摘要：Based on advanced computer technology, internet of things （lOT） technology, project management con- cept and professional technology and combined with the innovative theories, methods and techniques in earlier hy- dropower projects, the life-cycle risk management system of high earth-rock dam project for Nuozhadu project was developed. The system mainly includes digital dam, three-dimensional design, construction quality monito- ring, safety assessment and warning, etc, to integrally manage and analyze the dam design, constructional quality and safety monitoring information. It realized the dynamic updates of the comprehensive information and the safe- ty quality monitoring in the project life cycle, and provided the basic platform for the scientific management of the construction and operation safety of high earth-rock dam. Application in Nuozhadu earth-rock dam showed that construction safety monitoring and warning greatly helped accelerate the construction progress and improve project quality, and provided a new way for the quality safety control of high earth-rock dam.