大坝强震动响应参数放大效应研究

强震监测是大坝监测的重要内容,受地形地貌、场地条件和建筑物结构的影响,大坝在强震动条件下会呈现不同的响应特征。选用Seismosignal软件对监测记录数据进行预处理(数据波形错点剔除、基线校正、滤波去噪)和常规处理(数字积分和频谱计算),将处理得到的参数(加速度峰值、振幅谱峰值)与大坝高程进行相关性分析。研究结果表明:①随着高程的增加,加速度峰值和傅里叶谱峰值放大系数逐渐增加,具有明显的高程放大效应,坝顶放大效应明显,同时说明强震动引起的高程反应效应随高程的增加而逐渐增加;②3个方向上,加速度傅里叶谱幅值主频率主要集中在1.5～6.5 Hz频带范围内,而对其他频带起到滤波作用。研究成果可为大坝安全评价提供参考资料。

Amplification Effect of Response Parameters of Dam Strong Motion

Strong earthquake monitoring is an important content of dam monitoring.The response of dam subjected to strong motion influenced by geomorphology,site condition and structure of buildings is different.We made a series of preprocessing (eliminating wrong point,baseline correction,bandpass filter) and conventional processing (digital integration and spectrum calculating) for the monitoring record via using the Seismosignal software;and then analyzed the correlation between parameters (the peak of acceleration and Fourier amplitude) and the dam height.The results of analysis revealed that 1) the amplification of peak acceleration and peak Fourier amplitude increased with the increase of elevation,and the amplification at the dam crest was obvious,so did the altitude effect caused by strong-motion;2) the peak dominant frequencies of the Fourier spectrum in three directions (transverse,longi tudinal and vertical) mainly concentrated around 1.5-6.5 Hz,but filtered in other frequency bands.