摘要:
传统基于固定基函数的脉冲识别方法在处理复杂脉冲时存在一定的局限,且易受高频噪声干扰。针对这一问题,本研究基于深度学习U-Net模型与相对累积能量相结合的思路,提出了一种新的速度脉冲识别与提取方法,尝试解决真实地震动缺乏纯净脉冲标签的难题。首先,利用Dickinson & Gavin模型合成带噪信号作为训练集,构建U-Net模型通过大尺寸卷积核与镜像填充策略,以数据驱动的方式自适应滤除高频噪声,提取出平滑的低频脉冲。其次,在该平滑脉冲上应用峰值点法精准定位脉冲的起止时间,并计算该时段内的相对累积能量作为脉冲指标()。通过对人工标注数据集的统计分析,确立了>0.375作为脉冲型地震动的经验分类阈值,并验证了该方法在多方位角空间脉冲识别中的适用性。与经典小波变换方法的对比分析表明,U-Net在提取形态不对称等复杂脉冲时具有更高的保真度,能够有效克服小波变换因高频噪声引起的局部能量聚集与误报问题,并在应对不规则多脉冲形态时展现出更为突出的数据驱动自适应能力。此外,本研究的脉冲周期计算方法,有效避免了小波伪周期引起的系统性高估问题。本研究为海量地震动记录中速度脉冲的自动化、定量化识别提供了一种高效可靠的新途径。
Abstract:
Traditional pulse identification methods based on fixed basis functions have inherent limitations when dealing with complex pulses and are easily disturbed by high-frequency noise. To address this issue, this study proposes a new velocity pulse identification and extraction method combining the deep learning U-Net model and relative cumulative energy, attempting to solve the challenge of lacking pure pulse labels for real ground motions. First, synthetic noisy signals generated by the Dickinson & Gavin model are used as the training set, and a U-Net model is constructed to adaptively filter out high-frequency noise in a data-driven manner using large convolutional kernels and a reflect padding strategy, thereby extracting smooth low-frequency pulses. Second, the peak point method (PPM) is applied to this smooth pulse to accurately locate the start and end times, and the relative cumulative energy within this period is calculated as the pulse indicator (). Through statistical analysis of the manually labeled dataset, >0.375 is established as the empirical classification threshold for pulse-like ground motions, and the applicability of this method in multi-directional spatial pulse identification is verified. Comparative analysis with the classical wavelet transform method shows that the U-Net has higher fidelity when extracting complex pulses with asymmetric shapes, effectively overcomes the problems of local energy accumulation and false alarms caused by high-frequency noise in the wavelet transform, and exhibits a more prominent data-driven adaptive capability when dealing with irregular multi-pulse shapes. In addition, the pulse period calculation method in this study effectively avoids the systematic overestimation problem caused by the wavelet pseudo-period. This study provides a new, efficient, and reliable approach for the automated and quantitative identification of velocity pulses from massive ground motion records.