【作者】 杨弘；

【导师】 练继建；

【作者基本信息】 天津大学 ， 水利水电工程， 2008， 博士

【摘要】 高坝消力塘作为防护下游河床的结构,其自身在高速水流冲击下的安全性是实现消能和防冲目的的关键所在,国内外都不乏破坏的实例。高坝消力塘防护结构的工作和破坏机理十分复杂,是高速水流水动力特性与防护结构的结构动力特性耦合作用的结果。本文结合模型试验、原型观测和数值分析,研究高坝消力塘水动力荷载特性,开展耦合动力分析的数值模拟方法研究,揭示消力塘防护结构的受力特点、工作机理及失稳的动力过程。并在此基础上将力学分析结果、专家经验、人工智能技术有机融合,提出高坝消力塘防护结构的健康诊断方法。主要成果包括:(1)引用水跃和冲击射流的研究成果,详细分析了底流和挑跌流消力塘内的水流流态特征,探讨了这两种型式消力塘内时均压力和脉动压力的分布规律。(2)开展板块之间、板块与基岩间缝隙脉动压力传播规律研究,着重研究了缝隙宽度对脉动压强的影响。(3)开展止水破坏情况下底部渗压与表面动水压力的耦合作用机理研究,分析了渗压耦合作用对板块下表面不同区域时均动水压强、脉动压强的影响,并研究了不同止水破坏方式板块上举力的变化情况。(4)探讨了挑跌流和底流消力塘内板块及边坡的最大上举力的预报方法;系统分析了水流脉动压力相关尺度、消力塘底板尺寸、上下表面脉动压力的相关特性对底板水流上举力的影响,基于此对消力塘底板块尺寸优选进行了研究,并对透水底板上举力降低的原因进行了初步分析。(5)分析了消力塘底板的失稳破坏过程、稳定性计算模式及它们之间的内在联系,并对消力塘底板稳定性的控制指标进行了研究。(6)对高坝水垫塘防护结构泄洪振动进行了原型观测,全面分析防护结构正常工作状态下的动力响应特性。(7)分析了水垫塘底板失稳破坏各个阶段的动位移响应特性,提出可以利用底板动位移响应来识别水垫塘防护结构的稳定性。基于粘结滑移、非线性接触及流固耦合理论,建立水垫塘底板、水体、基岩、锚固钢筋的耦合有限元模型,计算不同破坏状态下底板块的极限动位移,结合原型观测结果进行动位移响应特性的分析,从而对水垫塘底板的稳定性进行识别。(8)计算了水垫塘底板振动信号的正常盒维数区间和动力失稳过程不同阶段的盒维数变化,并且结合时域、幅值域、频域分析方法,对水垫塘底板振动特征进行了分析与比较,结果显示分形维数对于水垫塘底板泄洪振动异常情况很灵敏。利用分形盒维数对水垫塘底板振动的主要故障信号进行了分析与识别,明确了分形维数与故障特征之间的内在联系。(9)通过对模型实验、原型观测、耦合动力数值模拟结果进行综合归纳分析,将力学分析结果、专家经验、人工智能(AI)技术有机融合,提取与防护结构破坏相关的敏感特征量,建立高坝泄洪防护结构安全监控的理论模型、监控指标,构建高坝消力塘防护结构的健康诊断系统。更多还原

【Abstract】 The safety of protecting structure in high dam plunge pool is the key to success or failure of energy dissipation, there is no lack of the destructive example at home and abroad. Working and destruction mechanism of protecting structure in high dam plunge pool is very complicated. It is coupling effect result between hydrodynamic characteristics of high speed streams and structural dynamics characteristics of protecting structure. This paper studies hydrodynamic characteristics in high dam plunge pool and numerical value imitates for coupled dynamics analysis by model experiment, prototype observation and numerical analysis to open out force characteristics, working mechanism and failure dynamic process of protecting structure in plunge pool. Basing on that, mechanical analysis result, expert experience and artificial intelligence (AI) technology are organically amalgamated to suggest the health diagnosis method for protecting structure in high dam plunge pool. The main achievements include as follows:(1)With research results of hydraulic jump and impinging jet,flow patterns in stilling basin and plunge pool are analyzed in detail, the distributing characteristics of mean pressure and fluctuating pressure are investigated.(2)It is analyzed in the paper of the characteristics of the propagation of the pressure wave within the contraction joints among slabs and cracks among slabs and bedrock. Influences on fluctuating pressure are especially studied by width of joints and cracks.(3)When water-stop is failure, coupling mechanism between osmotic pressure under slabs and hydrodynamic pressure upper slabs is studied. Influences on time averaged pressure, fluctuating pressure in each area under slabs are analyzed by osmotic pressure coupling. That is also investigated the uplift forces changing with different way of water-stop failure.(4)Forecast ways of maximal uplift forces acting on slabs or slope in stilling basin and plunge pool are investigated. Influences on the uplift forces acting on the slabs by fluctuating pressure integral scale, the size of stilling basin slabs and correlation characteristics for fluctuating pressure upper and under the slabs are studied systemically. Basing on that, this paper discusses the size optimization of stilling basin slabs and analyzes the reason for uplift forces decrease of the pervious slabs.(5)The steady losing and destroying process, stability calculation pattern of slabs in plunge pool and inherent relationship between them are analyzed,stability control indexes for slabs in plunge pool are investigated.(6)Prototype observation for the flood discharge vibration of protecting structure in high dam plunge pool is carried out to analyze fully dynamic respond characteristics of protecting structure working regularly.(7)The paper defines the response characteristic of dynamic displacement about stability failure process for plunge pool slabs, the method is proposed by means of dynamic displacement response to discriminate the stability of plunge pool slabs. Based on bond-slip theory, nonlinear contact theory and fluid-structure coupling theory, coupling three dimensional finite element model about plunge pool slabs, water, bedrock and anchor bar is established, limiting dynamic displacement considering phases of stability failure is studied in this paper, the response characteristic of dynamic displacement is analyzed in virtue of prototype observation results, and stability of plunge pool slabs are predicted.(8)The box dimension for slabs vibration curve in plunge pool of working regularly and the different stage of failure dynamic process is calculated. The vibration feature is analyzed and compared in time-amplitude-frequency domain. The results demonstrate that the fractal dimension is sensitive to abnormal vibration of slabs in plunge pool. The main malfunction signals are distinguished and analyzed using fractal box dimension to make it clear that the inner link between fractal dimension and the main malfunction characteristic.(9)The results of model experiment, prototype observation and coupled dynamics numerical simulation are synthesized. Mechanical analysis result, expert experience and artificial intelligence (AI) technology are organically amalgamated to extract sensitive characteristic variable about protecting structure failure. The paper puts forward theoretical model, monitoring indexes for safety monitoring of the high dam flood discharge protection structure, establishes health diagnosis system for protecting structure in high dam plunge pool.更多还原