重力坝不灌浆斜缝的工作性态分析

重力坝分缝类型中，斜缝是较合理也是最复杂的一种，其工作性态与大坝整体安全息息相关。本文以亭下水库为例，在分析不灌浆斜缝变形实测资料基础上，结合薄层有限元计算，分析斜缝的工作性态。实测与计算结果表明，运行期斜缝处于受压状态。只要进行合理分缝，斜缝重力坝的整体性态还是可以保证的。     

应用实测资料检验砌石重力坝加高效果

为有效监控新型结构、材料和施工工艺在砌石重力坝加高工程中的应用效果,了解施工期及运行期大坝安全性态的发展,对清凉山实测资料进行了全面分析.资料分析表明,新型结构设计合理,新旧大坝结合良好,大坝工作性态良好.     

实体重力坝应力计算过程分析

实体重力坝应力分析是重力坝设计中的关键问题之一,而重力坝的应力状态又是重力坝的强度核算、材料分区和构造分缝的主要依据.重力坝的应力计算涉及众多因素,特别是水作用引起的扬压力对重力坝的稳定和应力影响较大.正确计算重力坝的荷载、全面分析重力坝的应力,真正理解重力坝应力分析过程的真谛,是合理设计重力坝的关键所在.通过重力坝应力计算实例,深入坝体内部,全方位计算重力坝的应力,突出主应力问题分析,为重力坝设计者提供一个应力分析的全真过程.     

三门峡工程353平硐工作性态分析

对３５３平硐钢筋混凝土衬砌钢筋应力及拱圈温度缝开合度进行了计算分析，并建立了反映温度缝变化规律的数学模型。分析结果表明，３５３平硐工作性态正常。     

多轴等效应变损伤模型及其在混凝土坝工作性态分析中的应用

基于混凝土单轴拉伸应力应变曲线模型和四参数等效应变,给出一种修正的四参数多轴等效应变损伤模型,通过与单轴拉伸、单轴压缩、双向拉伸、双向压缩、双向拉压以及三向压缩这6种受力状态的试验资料进行对比以验证其有效性。采用该多轴等效应变损伤模型对混凝土剪切试验组合受力情况、混凝土重力坝和混凝土拱坝等结构工作性态进行数值分析,得到静力荷载下的结构损伤和应力响应,评价了结构正常工作性能及安全性。结果表明,剪切试验数值模拟结果与试验成果吻合良好,可以对以剪切为主的组合受力情况进行分析,该模型适用于复杂应力状态下的计算;典型重力坝和拱坝损伤分布区域及应力分布规律合理,该模型可以对混凝土坝工作性态及其安全性进行分析。     

三门峡工程353平酮工作性态分析

对３５３平硐钢筋混凝土衬砌钢筋应力及拱圈温度缝开合度进行了计算分析，并建立了反映温度缝变化规律的数学模型。分析结果表明，３５３平硐工作性态正常。     

江口大坝首次蓄水期实测变形与应力分析

介绍了江口拱坝首次蓄水期的变形与应力实测资料分析结果,通过变形应力各类模型与理论计算成果的对比分析,对大坝整体工作性态进行了评价。     

布置跨横缝泄洪孔大坝上游面混凝土裂缝成因仿真分析研究

采用三维结构温度徐变仿真计算方法,利用实测环境气温和实测混凝土入仓温度,对跨横缝布置泄洪孔的混凝土重力坝进行了分析研究.结果表明,气温骤降是大坝上游面混凝土产生裂缝的主要原因.     

拱坝结构损伤的多测点R／S分析

为了研究大坝监测资料与结构完整性的关系,利用R/S分析法对实测资料时间序列进行分时段分析,根据计算的分形维数判断坝体结构的损伤程度。实例计算结果表明:大坝结构完整,实测资料的变化规律相似性越高,其分形维数越小;当大坝结构出现损伤,实测资料的变化规律越复杂,其分形维数越大;与传统的仿真模拟相比,R/S分析法更接近大坝实际工作性态,具有很强的适用性。     

布置跨横缝泄洪孔大坝上游面混凝土裂缝成因仿真分析研究

采用三维结构温度徐变仿真计算方法，利用实测环境气温和实测混凝土入仓温度，对跨横缝布置泄洪孔的混凝土重力坝进行了分析研究。结果表明，气温骤降是大坝上游面混凝土产生裂缝的主要原因。     

DISTRIBUTION OF WAVE-INDUCED EXCESS MOMENTUM FLUXES OVER DEPTH AND APPLICATION TO THREE-DIMENSIONAL NUMERICAL MODELING OF WAVE-CURRENT INTERACTIONS

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REFLECTION OF OBLIQUE INCIDENT WAVES BY PERFORATED CAISSONS WITH TRAVERSE WALL

The interaction of oblique incident waves with infinite number of perforated caissons is investigated. The fluid domain is divided into infinite sub-domains by the caissons, and eigen-function expansion is applied to expand velocity potentials in each domain. A phase relation is introduced for wave oscillation in each caisson, and the structure geometry is considered in constructing the models of reflection waves. The reflected waves with the present analysis include all of the waves traveling in different directions when incident wave period is short. Numerical examinations show that velocities at the inner and outer sides of the front walls of caissons are close to each other, and reflection coefficients satisfy the energy conservation relation very well when porous effect parameter is infinite. Numerical results show that the reflection coefficients of oblique incident waves are smaller for shorter caissons at low frequency, and decrease with the increase of wave incident angle.     

THREE-DIMENSIONAL NUMERICAL MODELLING OF THE WAVE-IN- DUCED RIP CURRENTS UNDER IRREGULAR BATHYMETRY

A process-based 3-D hydrodynamic model is established to simulate the rip current structures under irregular bathymetry.The depth-varying wave-induced residual momentum,the surface rollers,the turbulent mixing and the wave-current interactions are considered.Experimental datasets are used to validate the model,and it is shown that the model can effectively describe the 3-D structures of the rip currents in both normal and oblique wave incident cases.The flow patterns of the rip currents see various characteristics for different incident wave directions.In the normal incident case,pairs of counter-rotating primary circulation cells are formed,and an offshore rip flow occurs in the embayment troughs.The peak seaward velocities occur at the top of the bed boundary layer,and the undertow is incorporated in addition to the rip currents.In the oblique incident case,the longshore currents are dominant,which result in a meandering flow along the depth contour,and the undertow is weaker compared to that in the normal incident condition.     

NUMERICAL ANALYSIS OF THE NON-NEWTONIAN BLOOD FLOW IN THE NON-PLANAR ARTERY WITH BIFURCATION

A numerical analysis of non-Newtonian fluid flow in non-planar artery with bifurcation was performed by using a finite element method to solve the three-dimensional Navier-Stokes equations coupled with the non-Newtonian constitutive models, including Carreau, Cross and Bingham models. The objective of this study is to investigate the effects of the non-Newtonian properties of blood as well as curvature and out-of-plane geometry in the non-planar daughter vessels on the velocity distribution and wall shear stress. The results of this study support the view that the non-planarity of blood vessels and the non-Newtonian properties of blood are of important in hemodynamics and play a significant role in vascular biology and pathophysiology.     

FLOW-PIPE-SEEPAGE COUPLING ANALYSIS OF SPANNING INITIATION OF A PARTIALLY-EMBEDDED PIPELINE

The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline. The pipeline spanning initiation is experimentally observed and discussed in this article. It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation. A flow-pipe-seepage sequential coupling Finite Element Method (FEM) model is proposed to simulate the coupling between the water flow-field and the soil seepage-field. A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe. Parametric study is performed to investigate the effects of inflow velocity, pipe embedment on the pressure-drop, and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation. It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.     

斜流效应的分析计算

参考国内外有关资料结合水力学试验的基础上,通过合理的简化假设 建立了斜流效应的半经验概算方法,并对葛洲坝和三峡工程中有关斜流效应进行了计算和试验验证。方法可供航道水力学研究及航道工程设计参考。     

GENERATION OF NONLINEAR INTERNAL WAVES ON CONTINENTAL SHELF

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STUDY ON A NEW APPROACH OF CAVITATION EROSION TEST FOR NONMETALLIC MATERIALS

１．　ＩＮＴＲＯＤＵＣＴＩＯＮＣａｖｉｔａｔｉｏｎｄａｍａｇｅｏｆｍａｔｅｒｉａｌｓｉｎｖｏｌｖｅｓｍａｎｙｆａｃｔｏｒｓ，ｓｕｃｈａｓｔｈｅｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓｏｆｍａｔｅｒｉａｌ，ｔｈｅｐｒｏｐｅｒｔｉｅｓｏｆｌｉｑｕｉｄｍｅｄｉａ，ｔｈｅｆｌｏｗｆｉｅｌｄｃｈａｒａｃｔｅｒｉｓｔｉｃｓ，ｅｔｃ．Ｉｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｍｅｃｈａｎｉｓｍｏｆｃａｖｉｔａｔｉｏｎｅｒｏｓｉｏｎｉｓｖｅｒｙｃｏｍｐｌｉｃａｔｅｄ．Ｕｐｔｏｎｏｗ，ｔｈｅｃａｐａｂｉｌｉｔｙｏ…     

基于无人机倾斜摄影的白格堰塞区三维重建

为研究倾斜摄影技术在堰塞灾害现场的适用性,在介绍倾斜摄影的建模原理的基础上,阐述了无人机倾斜摄影的步骤要点,并在白格堰塞现场进行了无人机飞行作业。以无人机所采集的POS数据、图像数据为基础,进行了图像筛选、空中三角测量计算、点云稠密重建及点云三角化,完成了白格堰塞区三维数字模型重建。以数字高程模型、数字地表模型、正射影像等形式展示了白格堰塞区地貌,并测算了白格堰塞体形态、结构等方面的特征信息。结果表明,无人机倾斜摄影可以适应堰塞现场的复杂环境,具备快速进入目标区域、高效完成测绘任务的能力。     

NUMERICAL PREDICTION OF SUBMARINE HYDRODYNAMIC COEFFICIENTS USING CFD SIMULATION

The submarine Hydrodynamic coefficients are predicted by numerical simulations.Steady and unsteady Reynolds Averaged Navier-Stokes(RANS) simulations are carried out to numerically simulate the oblique towing experiment and the Planar Motion Mechanism(PMM) experiment performed on the SUBOFF submarine model.The dynamic mesh method is adopted to simulate the maneuvering motions of pure heaving,pure swaying,pure pitching and pure yawing.The hydrodynamic forces and moments acting on the maneuvering submarine are obtained.Consequently,by analyzing these results,the hydrodynamic coefficients of the submarine maneuvering motions can be determined.The computational results are verified by comparison with experimental data,which show that this method can be used to estimate the hydrodynamic derivatives of a fully appended submarine.