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重大水利水电工程地震动输入参数必须根据专门的地震危险性分析结果来确定。目前由地震危险性分析得到的一致概率反应谱具有包络的意义,不能反映实际地震的频谱特性,输入“一致概率反应谱”可能导致地震作用偏大;拟合设计反应谱人工生成地震动加速度时程的频率非平稳性也没有得到很好解决。为了解决这些问题,得到与坝址地震危险性一致、具体地震的输入参数,结合沙牌大坝提出了一套适用于重大水利水电工程基岩场地地震动输入参数确定方法:通过以有效峰值加速度为参数的概率地震危险性计算分析,确定坝址不同超越概率下的有效峰值加速度及对坝址贡献最大的潜在震源区;在最大贡献潜在震源内利用震级空间联合分布概率最大法确定坝址设定地震,依据加速度反应谱衰减关系确定与坝址设定地震对应的设计反应谱;根据设定地震结果和时变功率谱模型参数衰减关系确定时变功率谱,将时变功率谱和最小相位谱按三角级数叠加法进行强度和频率非平稳地震加速度时程合成。在对沙牌坝址区域的地震活动性及地震构造环境分析评价的基础上,采用上述方法,得到了坝址基岩场地不同超越概率下的有效峰值加速度、设计反应谱、强度和频率非平稳地震加速度时程等地震动输入参数。
The input parameters of earthquakes in major water conservancy and hydropower projects must be determined according to the special seismic risk analysis results. At present, the consistent probability response spectrum obtained from the analysis of seismic hazard has the meaning of envelopment, and can not reflect the spectral characteristics of the actual earthquake. The “uniform probability response spectrum” of the input may lead to a large earthquake effect. The fitted design response spectrum generates the earthquake The frequency nonstationarity of the moving acceleration time series has not been well solved. In order to solve these problems, we get the input parameters which are consistent with the seismic risk of dam site and the specific earthquakes. Combining with Shapai Dam, we put forward a set of method to determine the ground motion input parameters of bedrock ground for major water conservancy and hydropower projects: As the parameters of the probability of seismic risk calculation and analysis to determine the effective peak acceleration under different probabilities of dam site and potential contribution to the dam area of the largest potential source; maximum contribution potential source within the joint use of magnitude distribution maximum probability method to determine the dam location According to the attenuation relationship of the acceleration response spectrum, the design response spectrum corresponding to the dam setting earthquake is determined. The time-varying power spectrum is determined according to the setting earthquake results and the attenuation relationship of the time-varying power spectrum model parameters. The time-varying power spectrum and the minimum phase The spectrum is synthesized by the trigonometric series superposition method with non-stationary frequency and seismic acceleration time history. Based on the analysis and evaluation of the seismic activity and the seismic tectonic environment of the Shaba dam site, the effective peak acceleration at different overrun probabilities of the bedrock site of dam site is obtained by the above method. The design response spectrum, intensity and frequency of non-stationary Earthquake acceleration time history and other ground motion input parameters.