高拱坝体系整体抗震安全评价方法研究

采用非线性地震波动反应分析方法，将坝体、地基、库水的强震反应本质上作为满足体系中接触面边界约束条件的波传播问题，在时域内以显式有限元方法求解。在不同概率水平的地震波作用下进行高拱坝与地基体系的有限元时程分析，并建议了以坝体位移反应发生突变为依据的拱坝体系整体失稳判断准则，从而建立了进行高拱坝体系整体抗震安全评价的方法，并以小湾拱坝为算例，对其抗震安全度作出初步评价。     

拱坝非线性地震反应分析

本文根据一致粘弹性模型的概念，引入应变率的影响，将混凝土静态William-Warnke三参数模型改造成一致粘塑性William-Warnke三参数本构模型，并用这个模型对某高拱坝进行了非线性地震响应分析，与线弹性模型和应变率无关的William-Warnke三参数模型的结果进行了比较，初步探讨了应变率对拱坝地震反应的影响。     

Parallel computation of seismic analysis of high arch dam

Parallel computation programs are developed for three-dimensional meso-mechanics analysis of fully-graded dam concrete and seismic response analysis of high arch dams （ADs）, based on the Parallel Finite Element Program Generator （PFEPG）. The computational algorithms of the numerical simulation of the meso-structure of concrete specimens were studied. Taking into account damage evolution, static preload, strain rate effect, and the heterogeneity of the meso-structure of dam concrete, the fracture processes of damage evolution and configuration of the cracks can be directly simulated. In the seismic response analysis of ADs, all the following factors are involved, such as the nonlinear contact due to the opening and slipping of the contraction joints, energy dispersion of the far-field foundation, dynamic interactions of the dam-foundation- reservoir system, and the combining effects of seismic action with all static loads. The correctness, reliability and efficiency of the two parallel computational programs are verified with practical illustrations.     

高拱坝伸缩横缝间布设阻尼器对坝体地震反应影响的研究

对设置伸缩横缝的小湾高拱坝结构，应用子结构理论，分别就正常高水位与常遇低水位两种水位工况，考虑坝体伸缩横缝在地震交变荷载作用下反复开合引起的缝面间滑移、接触等效应的影响，坝体-库水的相互作用而产生的动水压力的影响，对坝体的抗震性能进行了地震反应分析。对伸缩缝间设置阻尼器这新的设计思想进行了可行性的研究，论证推导了阻尼器的计算模型，探讨了阻尼器对坝体抗震性能的影响。     

拱坝非线性地震反应分析

以乌东德拱坝为对象,进行了拱坝非线性地震反应分析。结果表明:坝体损伤区域明显大于坝体混凝土按线弹性材料计算时最大主应力超过抗拉强度的区域,说明传统方法低估了拱坝的开裂范围,偏于危险;考虑基岩的非线性后,坝体损伤总体上要有所减小;坝基岩体剪胀角对坝基岩体的屈服和坝体混凝土的损伤都有影响,但是规律不明确,因此应该进行基岩剪胀角的敏感性分析。     

Experimental study of seismic overloading of large arch dam

A dynamic overloading model test has been carried out on a shaking table for an arch dam of 278 m in height to investigate its behaviours under strong earthquake. The model system included the arch dam with contraction joints, part of reservoir, partial foundation rock with topographic feature near the dam. A damping boundary consisting of viscous liquid has been used to simulate the effect of dynamic energy emission to far field, which made the dynamic interaction between dam and foundation in model arch dam system be represented properly. Three sets of different seismic waves of design level have been used as the input to investigate the difference in the responses of arch dam. Artificial waves of different levels have been used to verify the behaviours of arch dam under seismic overloading. Since the opening of joints during strong earthquake reduced the response acceleration and tensile arch stress, cantilever stress on downstream face exceeded the tensile strength first for the model dam. And the arch dam responded in a non‐linear way when input seismic load increased. Some cracks appeared near abutments, and the damage made the natural frequency of arch dam to drop obviously, but the static function did not seem to change for the model tested. Copyright © 2005 John Wiley & Sons, Ltd.     

双向地震波输入时振动方向对拱坝地震响应的影响

拱坝-地基三维地震响应分析中大多只分析入射地震波在拱坝-地基系统坐标系方向输入时的地震响应,而事实上,垂直入射的剪切波其振动方向是不确定的,地震波动的合理输入对拱坝-地基系统的地震响应分析起着决定性的作用.本文研究了拱坝-地基系统在双向地震波输入时不同振动方向对拱坝-地基系统地震响应的影响.计算结果表明:在双向地震波输入情形时,拱坝位移及应力响应最大值均不是发生在传统方法的横河向或者顺河向,而是与输入地震波相关,所以在研究拱坝-地基三维地震响应时有必要考虑入射地震波振动方向的影响.     

Integrative seismic safety evaluation of a high concrete arch dam

An integrative seismic safety evaluation of an arch dam should include all sources of nonlinearities, dynamic interactions between different components and the external loads. The present paper investigates the calibration procedure and nonlinear seismic response of an existing high arch dam. The first part explains the conducted analyses for the static and thermal calibrations of the dam based on site measurements. The second part investigates the nonlinear seismic analysis of the calibrated model considering the effect of joints, cracking of mass concrete, reservoir–dam–rock interaction, hydrodynamic pressure inside the opened joints and the geometric nonlinearity. Penetration of the water inside the opened joints accelerates the damage process. The integrative seismic assessment of a case study shows that the dam will fail under the maximum credible earthquake scenario. The dam is judged to be severely damaged with extensive cracking and the joints undergo opening/sliding. A systematic procedure is proposed for seismic and post-seismic safety of dams.     

Wave passage and incoherency effects on seismic response of high arch dams

The effects of incoherency and wave-passage on the nonlinear responses of concrete arch dams are investigated in this study. A double curvature arch dam is selected as a numerical example. The reservoir is modeled as a compressible material and the foundation is modeled as a massless medium. Ground motion time-histories are artificially generated using the Monte Carlo simulation approach. Four different finite element models (FEM) are considered: uniform excitation; incoherence effect; wave passage effect; and both incoherence and wave passage effects. It was revealed that modeling multiple-supports excitation could have a significant impact on the structural response of the dam by inducing a pseudo-static effect. Also, it was concluded that the coherency effect overshadows the wave passage effect and the results obtained from non-uniform excitation of FEM, including the wave passage effect, is close to the results of the FEM when it is uniformly excited.     

Seismic safety of high concrete dams

China is a country of high seismicity with many hydropower resources. Recently,a series of high arch dams have either been completed or are being constructed in seismic regions,of which most are concrete dams. The evaluation of seismic safety often becomes a critical problem in dam design. In this paper,a brief introduction to major progress in the research on seismic aspects of large concrete dams,conducted mainly at the Institute of Water Resources and Hydropower Research(IWHR) during the past 60 years,is presented. The dam site-specific ground motion input,improved response analysis,dynamic model test verification,field experiment investigations,dynamic behavior of dam concrete,and seismic monitoring and observation are described. Methods to prevent collapse of high concrete dams under maximum credible earthquakes are discussed.     

加强高土石坝抗震研究的现实意义及工作展望

围绕西部大开发和南水北调战略的需要,对高土石坝抗震研究的现实意义和若干关键问题及研究现状进行了论述。并针对高土石坝震害资料获取与整理、坝料动力特性研究、多耦合非线性动力分析理论和方法、动力破损特征与地震灾害机理、地震安全评价与震害预测的基本理论、抗震设计及抗震措施、震灾机理和抗震理论的动力模型试验等研究提出了工作设想和展望,并提出了建立土石坝地震安全评价及防灾对策专家系统的基本思路。     

煤矿采动与地震联合作用下建筑物损伤演化致灾分析

针对煤矿采动区建筑物的地震损伤演化过程尚不明晰的问题,考虑到煤矿采动与地震联合成灾机制的复杂性,基于损伤力学理论,采用地震工程学和开采学理论,建立煤矿采动损害影响下的建筑物动力损伤判据,探讨煤矿采动与地震联合作用下建筑物损伤演化灾变过程,通过有限数值计算分析煤矿采动建筑物地震动力破坏的损伤成灾机制。结果表明:"联合作用"能够更好的描述煤矿采动与地震对建筑的破坏作用,煤矿采动损害影响下建筑物的次生损伤与其应力成反比,煤矿采动加剧了建筑的地震动力响应,所产生的次生损伤不断发展演化,导致建筑物的薄弱层位置形成塑性铰,严重削弱了建筑物的抗震性能。     

MathematicalsimulationofmoderateandstrongearthquakesequenceinZhujiangDeltaanditssurroundingareasinth

ＭａｔｈｅｍａｔｉｃａｌｓｉｍｕｌａｔｉｏｎｏｆｍｏｄｅｒａｔｅａｎｄｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓｅｑｕｅｎｃｅｉｎＺｈｕｊｉａｎｇＤｅｌｔａａｎｄｉｔｓｓｕｒｒｏｕｎｄｉｎｇａｒｅａｓｉｎｔｈｉｓｃｅｎｔｕｒｙａｎｄｄｉｓｃｕｓｉｏｎｏｎｓｅ...     

高边坡桥墩倾斜机理分析与安全性评价

高陡边坡桥墩同时承受上部结构传递的竖向荷载和桩周土体的侧向压力,墩柱受力性能复杂,易出现病害,影响桥梁安全。结合某高速公路桥墩倾斜的工程实例,对高陡边坡桥墩倾斜的机理进行分析,并对倾斜桥墩的安全性能进行评价。通过考虑边坡土体和桥墩的相互作用,采用数值方法对高陡边坡桥墩的受力特征进行研究,分析了墩柱倾斜和开裂的机理,并基于不同荷载下墩柱的内力组合,对墩柱的承载力进行评定。结果表明,边坡潜在滑移面受扰动后产生的坡体推力是引起墩柱倾斜的主要原因,坡体推力与车辆荷载及汽车制动力组合后,桥墩的承载力将不能满足设计要求。     

联合高分辨率地震和精细测井资料的剩余油气分析

寻找和开发剩余油气藏是提高采收率的关键.以往主要是通过测井、试井资料建立中高层渗透砂岩油藏的井间剩余油分布模型,并采用数学分析方法建立井间剩余油的预测模型.本文介绍了基于高分辨率地震和精细测井分析建立剩余油模型并结合数模分析的剩余油分析技术.利用该技术对辽河油田某断块进行了实际剩余油气分析,在开发方案设计和提高采收率方面取得了明显的效果.