施工期深水桥墩在船行波激励下的振动研究

Study on Vibration of Deep-water Bridge Piers during Construction under Excitation of Ship Traveling Waves

摘要:

船行波是作用于深水桥墩的主要动力之一，往往会引起桥墩出现明显振动而威胁其安全，因此研究施工期深水桥墩在船行波激励下的振动特性具有重要意义。根据合适的经验公式确定了船行波的主要参数，基于Morison方程推导了船行波浪力时程。基于ANSYS软件，采用动力有限元方法研究了船行波作用下深水桥墩的振动特性。研究表明，随着船速的增加，船行波的波高、波长与波浪压力幅值均提高，但波浪力频率降低。相比桩基淹没水位与正常蓄水位，承台淹没水位时船行波引起的桥墩动力响应最大。当某一船速对应的船行波频率与桥墩固有频率接近时，则会引起桥墩共振，因此通过合理规划船速，使船行波频率较大偏离结构固有频率即可显著降低桥墩动力响应。

Abstract:

The ship traveling wave is one of the main dynamic forces acting on the deep-water bridge piers, which frequently leads to obvious vibrations of bridge piers and threaten the safety of piers. Therefore, it is of great significance to study the vibration characteristics of deep-water bridge piers during the construction under excitation of ship traveling waves. The main parameters of ship traveling waves are determined according to the appropriate empirical formulas, and the time history of ship traveling wave forces are derived based on the Morison equation. Based on ANSYS software, the dynamic finite element method is adopted to study the vibration characteristics of deep-water bridge piers under the excitation of ship traveling waves. The study result shows that with the increase of ship speed, the wave height, wave length and the amplitude of wave force all increase， but the frequency of wave force decreases. Compared with the water level of submerging pile foundation and the normal water storage level, the dynamic responses of bridge pier induced by ship traveling waves are the largest for the water level of submerging the base slab. When the frequency of the ship traveling wave corresponding to a ship speed is close to the natural frequency of the pier, the pier resonance will be caused. Therefore, by reasonably planning the ship speed to make the frequency of ship traveling wave deviate significantly from the natural frequency of the structure, the dynamic response of piers can be significantly reduced.