考虑桩—土—结构相互作用的输电塔抗震性能研究

发布时间：2018-07-10 16:39

本文选题：桩-土-输电塔耦合体系 + 模态分析　；参考：《东北电力大学》2017年硕士论文

【摘要】：随着经济的高度发展和煤炭、石油等一次能源的紧缺,电力作为清洁的二次能源将逐渐成为主要的能源消费方式。国家电网公司提出建设全球能源互联网,而实现全球能源互联的第一步就是建设特高压电网,长距离、大跨越电力输送已成为常态。通常,在进行输电塔的设计时主要考虑风荷载的作用,但近年来地震荷载作用下输电塔发生破坏的例子屡见不鲜。调查表明,当输电塔发生震害时,大多可见基础及场地土的严重破坏。因此,开展土-上部结构相互作用对输电塔动力特性影响的工作是十分必要的。本文研究内容主要由以下三个部分组成:(1)在四种不同的场地条件下建立了四个考虑桩-土-上部结构相互作用的输电塔的有限元模型;在刚性地基条件下,建立一个输电塔的有限元模型。首先对这五个模型进行了模态分析,并对比它们之间周期和振型的特点,得出考虑相互作用后,输电塔的周期延长,振型滞后。其次,运用时程分析的方法分别对考虑相互作用的四个模型和刚性地基条件下输电塔的模型进行地震响应分析。对比计算结果得出,在软土和中软土场地条件下,桩-土-结构相互作用对结构的动力响应产生不利影响。(2)在软土场地条件下,建立四个横隔数目不一样的桩-土-输电塔整体有限元模型。分别对四个模型进行模态分析,并分别对比他们周期的特点,得出随着横隔数目的增加结构的周期变小。然后分别对四个模型进行地震响应分析,研究发现增加输电塔的横隔后,有效的减小了塔顶的位移峰值和加速度峰值,但是输电塔根部最大轴力和基底最大剪力有所增大。因此并不是横隔数目越多,输电塔的抗震性能越好。(3)在软土场地条件下,建立三个桩长不一样的桩-土-输电塔的整体有限元模型。分别对三个模型进行模态分析,桩长变长后结构的刚度变大,周期变小。对三个桩长不同的模型进行动力时程响应分析,研究发现桩长增加后塔顶的位移和加速度减小,但是塔根部最大轴力和基底剪力增大。因此在工程实际中要根据现场土体条件合理选择桩的长度,并不是桩长度越长,上部结构抗震性能越好。
[Abstract]:With the development of economy and the shortage of primary energy, such as coal and oil, electric power, as a clean secondary energy, will gradually become the main way of energy consumption. The State Grid Corporation has proposed the construction of the global energy Internet, and the first step to realize global energy interconnection is to build an ultra-high voltage power grid. Long distance and long span power transmission has become the norm. Usually, the wind load is the main consideration in the design of transmission tower, but in recent years, there are many examples of transmission tower failure under earthquake load. The investigation shows that when the transmission tower is damaged by earthquake, the foundation and site soil are damaged seriously. Therefore, it is necessary to study the effect of soil-superstructure interaction on the dynamic characteristics of transmission towers. This paper mainly consists of the following three parts: (1) the finite element model of four transmission towers considering pile-soil-superstructure interaction is established under four different site conditions; A finite element model of transmission tower is established. First, the modal analysis of the five models is carried out, and the characteristics of the periods and modes between them are compared. After considering the interaction, the period of the transmission tower is prolonged and the mode is delayed. Secondly, the seismic response of four models considering interaction and the model of transmission tower with rigid foundation are analyzed by time-history analysis method. The results show that the pile-soil-structure interaction has a negative effect on the dynamic response of the structure under the soft soil and medium soft soil conditions. (2) under the soft soil site condition, the pile-soil-structure interaction has a negative effect on the dynamic response of the structure. Four finite element models of pile-soil-transmission tower with different number of transverses are established. The modal analysis of the four models and the characteristics of their periods respectively show that the period of the structure becomes smaller with the increase of the number of transverses. Then the seismic responses of the four models are analyzed respectively. It is found that the peak displacement and acceleration of the tower are reduced effectively after the increase of the transect, but the maximum axial force at the base and the maximum axial force at the base of the transmission tower are increased. Therefore, the more the number of horizontal separation, the better the seismic performance of transmission tower. (3) under the condition of soft soil site, the integral finite element model of three pile-soil-transmission towers with different pile length is established. Modal analysis of the three models shows that the stiffness of the structure becomes larger and the period of the pile becomes smaller after the length of the pile becomes longer. The dynamic time-history response analysis of three models with different pile lengths shows that the displacement and acceleration of the tower top decrease with the increase of pile length, but the maximum axial force and the base shear force increase at the root of the tower. Therefore, the length of pile should be reasonably selected according to the condition of soil in the field in engineering practice. The longer the length of pile is, the better the seismic performance of superstructure is.
【学位授予单位】：东北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM753

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