基于泄流振动响应的结构振动反分析与安全评价研究

发布时间：2018-05-25 20:35

本文选题：反分析 + 泄流结构　；参考：《南昌大学》2015年硕士论文

【摘要】：我国的高坝建设规模居世界首位,这些已(在)建的拱坝在坝高、泄流量和泄洪功率等方面已居世界领先水平。泄流结构在宣泄洪水时,由于强烈紊动的水流往往具有很大的动能,极易导致泄水结构的剧烈振动甚至结构发生破坏。近年来,高速泄洪水流诱发泄流结构振动,从而影响工程运行安全,严重时会导致破坏的实例屡见不鲜。研究发现,泄流结构破坏的原因主要包括两个方面:结构动位移超过振动安全标准;结构动应力响应过大导致振动疲劳破坏。因此,获取流激振动下的泄流结构的动位移值和动应力值,是评价泄流结构能否正常工作的重要依据。对泄流结构开展原型振动测试时,由于实测动力响应点数量是有限的,难以全面反映整个结构的振动响应特征,因此如何根据有限的实测点,反馈出整个结构的动力响应,尤其是针对水下结构的的动应力响应,进而对泄流结构运行安全评价具有重要意义,也是本文研究的主要问题,主要从以下三个方面展开研究:(1)通过对导墙模型的数值模拟,验证反分析方法的可行性。由于诱发导墙振动响应的水动力荷载是未知的,首先,本文以一典型水动力荷载作为输入,建立ANSYS有限元数值模型进行瞬态分析,从中提取测点的动位移响应时程,将其作为反分析方法的已知条件;其次,将这些测点的动位移响应谱作为已知输入,编制反分析基本程序,反演出诱发导墙振动响应的水动力荷载,实现了振源的识别,并将该动水荷载的实测值和计算值作对比,验证反分析方法的可行性;最后,再根据识别出的动水荷载正分析计算整个导墙结构的整体动位移响应均方根值,并进行了对比验证,同时基于模态叠加法,反演出整个结构的动应力响应。反演结果与瞬态响应计算结果对比表明,误差均控制在5%以内,验证了泄流结构振动响应的反分析方法是有效而可行的。(2)开展了基于有限测点的二滩拱坝原型动态响应场反演研究。以二滩拱坝原型工程为例,针对拱坝的六种不同泄水工况,开展了动位移振动响应测试,根据有限测点的动位移实测结果,实现了整个坝体的动位移场和动应力场的反演。通过每种工况下实测二滩拱坝B1~B7测点动位移响应时程,反分析拱坝泄流时所受三个等效动水荷载,该过程引入遗传算法,优化了识别结果。基于反演出的三个等效荷载进行正分析,计算出拱坝泄流时的整体动位移场,并与已知测点的动位移响应均方根进行了对比验证。基于模态叠加法,对上述六个工况的拱坝原型结构的整体动应力场进行了反演,得出坝体的整体动应力,并对坝体应力较大部位的动应力结果进行了分析。反演结果表明:①拱坝同一高程拱圈上各节点动位移响应均方根值呈现“中间大,两边递减”的变化趋势;②拱圈上的切向动应力响应变化趋势和动位移响应类似;③拱冠梁上各节点的切向动应力均方根值随高程的下降逐渐减小;竖向动应力均方根值随高程的升高逐渐增加。(3)对现有的工程结构振动安全评价标准进行了调研和整理分析,并结合二滩拱坝原型工程整体动位移场和动应力场的反演结果,对二滩拱坝在该六种工况下的运行安全进行了评价,结果表明,二滩拱坝在该六种工况下的泄洪振动是安全的。
[Abstract]:The construction of high dam in China ranks first in the world, and the arch dams built in the world have been leading the world's leading level in the aspects of dam height, discharge and flood discharge power. In the case of flood discharge, the turbulent flow often has great kinetic energy, which can easily cause the violent vibration of the discharge structure and even the structure damage. In recent years, The high speed flood discharge flow induces the vibration of the discharge structure, which affects the safety of the engineering operation, and the serious cases which will cause damage occur frequently. It is found that the cause of the failure of the leakage structure mainly includes two aspects: the structural dynamic displacement exceeds the vibration safety standard; the structural dynamic stress response is too large to cause the vibration fatigue damage. Therefore, the flow induced vibration is obtained. The dynamic displacement value and the dynamic stress value of the moving discharge structure are the important basis for evaluating the normal work of the discharge structure. In the prototype vibration test of the discharge structure, it is difficult to fully reflect the vibration response characteristics of the whole structure because the number of the measured dynamic response points is limited. The dynamic response of the structure, especially in response to the dynamic stress response of underwater structure, is of great significance to the safety evaluation of the discharge structure. It is also the main problem in this paper. It is mainly studied in the following three aspects: (1) the feasibility of the inverse analysis method is verified by the numerical simulation of the guide wall model. The hydrodynamic load of the vibration response is unknown. First, in this paper, a typical hydrodynamic load is used as the input, the ANSYS finite element model is established for transient analysis. The dynamic displacement response time history of the measuring point is extracted as the known condition of the inverse analysis method. Secondly, the dynamic displacement response spectrum of these measurements is used as the known input. The basic program of inverse analysis is made to induce the hydrodynamic load of the vibration response of the guide wall, and the identification of the vibration source is realized. The feasibility of the inverse analysis method is verified by comparing the measured value of the dynamic water load with the calculated value. Finally, the whole dynamic displacement response of the whole guide wall structure is calculated by the positive analysis of the identified dynamic water load. The dynamic stress response of the whole structure is compared with the modal superposition method. The comparison between the inversion results and the transient response shows that the error is controlled within 5%, and the inverse analysis method of the vibration response of the discharge structure is proved to be effective and feasible. (2) the original two beach arch dam based on the finite test point is carried out. The dynamic response field inversion of the two beach arch dam is taken as an example. The dynamic displacement vibration response test is carried out for the six different discharge conditions of the arch dam. The dynamic displacement field and the dynamic stress field of the whole dam are retrieved according to the measured results of the dynamic displacement of the finite measuring point. The B1~B7 measurement point of the two beach arch dam is measured under each working condition. The displacement response time course is used to reverse the analysis of three equivalent dynamic water loads when the arch dam is discharged. The genetic algorithm is introduced to optimize the identification results. Based on the positive analysis of the three equivalent loads on the anti performance, the whole dynamic displacement field of the arch dam is calculated, and it is compared with the root mean square root of the dynamic displacement response of the known test points. The integral dynamic stress field of arch dam archetype structure of the above six working conditions is retrieved by state superposition method, and the dynamic stress of the dam body is obtained, and the dynamic stress results of the large stress part of the dam are analyzed. The inversion results show that: (1) the root value of the dynamic displacement response of each node on the same elevation arch ring of the arch dam shows "the middle large, two sides". The trend of the change of the shear stress response on the arch and the response of the dynamic displacement is similar. (3) the root value of the tangential dynamic stress decreases with the elevation, and the root value of the vertical dynamic stress gradually increases with the elevation. (3) the existing safety evaluation criteria for the existing structural vibration are carried out. According to the investigation and analysis, and in combination with the inversion results of the dynamic displacement field and dynamic stress field of the two beach arch dam prototype, the operation safety of the two beach arch dam under the six conditions is evaluated. The results show that the flood discharge vibration of the two beach arch dam is safe under the six operating conditions.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TV312

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