Geotechnical Site Characterization with 3D Ambient Noise Tomography: Field Data Applications
Geotechnical Site Characterization with 3D Ambient Noise Tomography: Field Data Applications
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DOI：
10.1061/9780784484678.021
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发表时间：
2023-03
期刊：
影响因子：
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通讯作者：
Yao Wang;K. Tran;B. Cox;J. Vantassel
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文献类型：
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作者：
Yao Wang;K. Tran;B. Cox;J. Vantassel
我们开发了一种新的 3D 环境噪声断层扫描 (3D ANT) 方法，用于岩土工程场地表征。它需要使用地震检波器的二维表面阵列记录环境噪声场，然后从中提取实验互相关函数 (CCF) 并直接反演以获得横波速度 (VS) 结构。该方法包括使用 3D P-SV 弹性波方程计算合成 CCF 的正向模拟和将合成 CCF 与实验 CCF 相匹配以提取 VS 的伴随状态反演。与利用格林函数（GF）特性的传统被动源地震方法相比，该方法的主要优点是不需要每个接收器对两侧或远场波场具有相等的能量来恢复真实的GF。相反，源功率谱密度在分析过程中被反转，并纳入合成 CCF 的正向模拟中，以解释源能量分布。对合成数据进行测试后，将 3D ANT 方法应用于加利福尼亚州加纳谷井下阵列 (GVDA) 现场 3 小时的环境噪声记录，使用放置在 14 × 14 网格、间距为 5 m 的 196 个地震检波器的表面阵列。研究发现，倒置 3D VS 模型与 GVDA 现场之前的侵入性和非侵入性岩土工程表征工作一致。
We develop a new 3D ambient noise tomography (3D ANT) method for geotechnical site characterization. It requires recording ambient noise fields using a 2D surface array of geophones, from which experimental crosscorrelation functions (CCFs) are then extracted and directly inverted to obtain an S-wave velocity ( VS) structure. The method consists of a forward simulation using 3D P-SV elastic wave equations to compute the synthetic CCF and an adjoint-state inversion to match the synthetic CCFs to the experimental CCFs for extraction of VS. The main advantage of the presented method, as compared with conventional passive-source seismic methods using characteristics of Green’s function (GF), is that it does not require equal energy on both sides of each receiver pair or far-field wavefields to retrieve the true GF. Instead, the source power spectrum density is inverted during the analysis and incorporated into the forward simulation of the synthetic CCFs to account for source energy distribution. After testing on synthetic data, the 3D ANT method was applied to 3 h of ambient noise recordings at the Garner Valley Downhole Array (GVDA) site in California, using a surface array of 196 geophones placed on a 14 × 14 grid with 5 m spacing. The inverted 3D VS model is found to be consistent with previous invasive and noninvasive geotechnical characterization efforts at the GVDA site.