浅地表环境下ESPAC微动成像方法影响因素分析
Factors influencing the application of ESPAC-based microtremor survey in shallow surface environments
-
摘要: 扩展空间自相关(ESPAC)微动探测(天然源面波勘探)技术由于其简便快捷、效果精确等优势, 在浅部地层探测方面得到广泛应用。然而在实际应用中会出现基于ESPAC法提取的频散能量成像效果不尽人意的现象, 特别是不同的观测台阵布置情况会对采集的频散曲线提取结果造成一定的影响。通过对ESPAC法成像原理的分析研究, 利用背景噪声模拟的方法进行了天然源微动记录模拟实验, 比较了不同子波主频分布情况下频散能量的差异, 定量分析了不同台站布置情况和采集时间长度对频散能量成像质量的影响, 经过对比研究得到了ESPAC法在浅地表勘探时的成像规律, 在兼顾效率和探测成本的条件下最大程度提高基阶模式下的频散能量成像质量。将研究结果应用到工程实例中, 取得了不错的实际勘探效果, 验证了模拟结果的实用性。Abstract: The extended spatial autocorrelation (ESPAC)-based microtremor exploration(natural-source surface wave exploration) technology has been extensively used in shallow formation exploration owing to its simplicity, efficiency, and accuracy.However, the imaging effect of dispersion energy extracted based on the ESPAC method is unsatisfactory in practical applications.In particular, different observation array arrangements influence the extraction of dispersion curves from collected data.By investigating the imaging principle of the ESPAC method, this study conducted the simulation experiment of natural-source microtremor recording through ambient noise simulation.It compared the differences in dispersion energy under various dominant frequency distributions of wavelets.Moreover, it quantitatively analyzed the influence of different station arrangements and acquisition durations on the imaging quality of dispersion energy.The comparative study reveals the imaging patterns of the ESPAC method in shallow surface exploration.The ESPAC method can maximize the imaging quality of dispersion energy in the fundamental mode while considering both efficiency and exploration costs.The results of this study were applied to engineering application cases to further verify the simulation results.
下载: