复杂环境荷载下斜拉桥单塔结构动力响应试验

Experiment on Dynamic Response of Pile Group Cable-stayed Bridge Tower Foundation Subjected to Complex Environment Loads

就目前斜拉桥桥塔结构在复杂环境荷载(地震、波浪和水流)联合作用下的动力学模型,针对其构建难度高和数值模拟技术不成熟等问题,以某一试设计的斜拉桥中的桥塔为研究背景,首先利用重力-弹性力相似律和等效变换方法设计了几何比尺为1∶100的桥塔-群桩基础试验模型;其次设计了无水环境下白噪声扫频、正弦波共振,有水环境下地震、正弦波浪和水流单独/联合加载分级加载制度;最后采用大连理工大学的地震、波浪和水流联合模拟试验系统对该模型进行地震、波浪和水流单独/联合作用下的动力响应试验,分析了复杂环境荷载(地震、波浪和水流)作用下斜拉桥单塔结构上动水压力的变化趋势、动力响应特性和破坏机制。试验结果表明:当斜拉桥桥塔结构遭遇随机荷载作用时,加速度响应主要位于承台处,群桩上部和桥塔下部为应变较大区域,地震作用对动水压力贡献最大,波浪作用次之,水流影响最小;斜拉桥桥塔顶部动力响应幅值与输入的地震动特性相关,当地震荷载和高海况正弦波浪联合作用时,地震对桥塔顶部的加速度贡献较大,波浪作用贡献较小,但是也不容忽视。试验结果可为超大跨深水基础斜拉桥抗震设计规范的修订提供重要的参考。

In allusion to the numerical simulation technical and dynamic model obstacle in the dynamic response of the cable-stayed bridge tower foundation under the complex environment loading, a trial design of a cable-stayed bridge pylon foundation was employed as research background. First, a 1：100 scale dynamic test model of the pile group cable-stayed bridge tower foundation was designed according to the laws of similarity for elasticity and gravity and methods of equivalent transformation. Second, the loading systems of the sine wave and white noise under a dry environment as well as seismic waves, incident waves and current which were inputted individually or jointly with water state were designed. Finally, the experiment was conducted to analyze the dynamic response of the pile group cable-stayed bridge tower foundation subjected to complex environment loading based on the Earthquake, Wave and Current Joint Simulation System at Dalian University of Technology. The variation trend of dynamic hydraulic pressure, dynamic response characteristics and failure mechanism of the pile group cable-stayed bridge tower foundation under the complex environment loading were analyzed. The results show that the maximum acceleration response occurs at the pile-cap, and higher strain occurs at both the top of pile group and the bottom of pylon, when the cable-stayed bridge is under the random loading actions. The earthquake has a great influence on the hydrodynamic pressure, but wave and current have less influence on the hydrodynamic pressure. The dynamic response of the top of pylon is related with the type of the input earthquake wave. Under the joint action of the earthquake and wave, the acceleration of the top of the pylon contributed by the earthquake was strong enough that the influence of the wave on the acceleration of the top of the pylon can be neglected. The test results provide references for the revised seismic design code of long-span cable-stayed bridges with deep water foundation.