高坝泄洪诱发场地振动振源特性与传播规律研究

发布时间：2018-09-02 05:39

【摘要】：高坝大库水电工程是水资源综合利用的需要,随着高坝建设的发展,泄洪引发的振动问题备受关注。由于高坝大库泄洪落差大,巨大的下泄水体能量引起的水流脉动荷载会诱发泄流结构及其他水工建筑物产生振动,这种振动会由大坝上部结构传递至大坝基础,进而通过地基传递至周边场地,当到达一定能量时,会对场地建筑物的结构安全以及周边环境和附近居民的身体心理产生不利影响。然而,以往更多的是考虑水工结构自身的泄洪振动安全问题,对场地振动鲜有研究。针对这一现象,本文从结构振动系统的输入(泄流激励)、结构(泄流结构-场地振动传播系统)和输出(振动响应)三者相互关系入手,采用原型观测、数值模拟和物理试验相结合的研究方法,对多振源泄流脉动荷载联合诱发场地振动的振源特性、振动传播规律以及场地振动响应预测方法开展研究。取得以下成果:(1)分析了高坝泄洪引发场地振动现象的成因。基于泄洪诱发场地振动原型观测体系,对比研究背景振动情况下地脉动作用对场地的影响与泄洪情况下水流对场地的影响,评估场地土体动力特性和自振特性,研究泄洪诱发场地振动分布情况以及局部场地条件下的振动放大效应。(2)研究了泄洪诱发场地振动振源特性。通过引入时间-小波能量变换以及交叉小波变换方法,对泄流结构与场地振动信号中的水流脉动能量进行检测,识别场地振动主振源。建立不同振源时域和频域相关关系,分析各振源间的时-频域空间相关特性。建立各振源与场地振动的时域和频域相关关系,从振动能量同步变化角度,定量分析各振源对场地振动的贡献。(3)研究场地振动传播规律。建立了“多振源-泄流结构-地基-场地”有限元-无限元耦合动力分析模型。该模型很好的处理了振动波在无限域的传播问题,解决了大型复杂场地模拟的相关问题,其计算结果与原型观测结果吻合程度高。通过有限元-无限元耦合模型,研究了多振源激励诱发场地振动沿复杂河谷向下游传播及向地基传播(衰减、放大)的规律。在此基础上,进一步研究了不同振源影响下的场地振动传播特性。(4)研究建立场地振动预测方法。基于场地振动振源特性及振动传播规律,建立了多振源联合输入下基于传递函数的“噪声修正”场地振动预测体系。结果表明,该体系能够预测场地振动强度与频谱特性,解决了噪声影响下多振源联合输入系统预测难题。同时提出一种改进的EEMD和小波阈值联合滤波方法,该方法降噪能力强,能准确保留振动信号的有用信息,为场地振动的预测提供了保障。总之,高坝泄洪时不同泄水建筑物产生的水流脉动荷载是引起下游场地振动的主要原因。不同振源的振动特性不同,但又相互影响相互作用。不同泄洪方式,不同的场地土体,振源对场地振动的贡献以及在传播过程的衰减与放大规律有所不同。基于场地振动振源特性及振动传播规律建立的场地振动预测体系,在时域和频域内预测场地振动,可以为设计人员选择合理的泄洪调度方式提供依据,具有强烈的实际意义。
[Abstract]:With the development of high dam construction, the vibration caused by flood discharging has attracted much attention. Due to the large discharging drop of high dam, the fluctuating load of water flow caused by the energy of huge discharging water body will induce the vibration of discharge structure and other hydraulic structures, which will be caused by the vibration of the dam. When a certain amount of energy is reached, it will have a negative impact on the structural safety of the site buildings, the surrounding environment and the physical and mental health of the residents nearby. Aiming at this phenomenon, this paper begins with the relationship between the input (discharge excitation), the structure (discharge structure-site vibration propagation system) and the output (vibration response) of the structural vibration system, and adopts the method of prototype observation, numerical simulation and physical experiment to study the site vibration induced by the combined discharge pulsating load of multiple vibration sources. The results are as follows: (1) The causes of site vibration induced by flood discharge of high dams are analyzed. Based on the prototype observation system of site vibration induced by flood discharge, the influence of ground pulsation on site under background vibration and the effect of water flow on site under flood discharge are compared and studied. The influence of the site is evaluated, the dynamic and natural vibration characteristics of the soil are evaluated, and the distribution of the site vibration induced by flood discharge and the amplification effect under local site conditions are studied. (2) The source characteristics of the site vibration induced by flood discharge are studied. The pulsating energy of water flow in the dynamic signal is detected to identify the main vibration source of the site.The time domain and frequency domain correlations of different vibration sources are established,and the time-frequency domain spatial correlations between the vibration sources are analyzed.The time domain and frequency domain correlations between the vibration sources and the site vibration are established. Dynamic contribution. (3) Study the law of site vibration propagation. A finite element-infinite element coupled dynamic analysis model of "multi-source-discharge structure-foundation-site" is established. The model can well deal with the propagation of vibration wave in infinite domain, and solve the related problems of large complex site simulation. The calculated results are in good agreement with the prototype observations. Based on the coupled finite element-infinite element model, the propagation (attenuation, amplification) of site vibration induced by multi-source excitation along complex river valley is studied. The propagation characteristics of site vibration under the influence of different vibration sources are further studied. (4) The prediction method of site vibration is established. Based on the characteristics of vibration sources and the law of vibration propagation, a noise-corrected site vibration prediction system based on transfer function is established. The results show that the system can predict the site vibration intensity and spectrum characteristics, and solve the prediction problem of multi-source joint input system under the influence of noise. D and wavelet thresholding combined filtering method, this method has strong noise reduction ability, can accurately retain useful information of vibration signals, and provides a guarantee for site vibration prediction. The contribution of vibration sources to site vibration and their attenuation and amplification laws are different in different flood discharge modes, different site soils, and the propagation process. It is of great practical significance to provide reasonable basis for flood discharge dispatching.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV698.1
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本文编号：2218423