Coupling of SPT and 3D full waveform inversion for deep site characterization
Coupling of SPT and 3D full waveform inversion for deep site characterization
复制标题
DOI：
10.1016/j.soildyn.2020.106196
复制
发表时间：
2020-09
影响因子：
4
通讯作者：
Majid Mirzanejad;K. Tran;M. McVay;D. Horhota;Scott J. Wasman
中科院分区：
文献类型：
--
作者：
Majid Mirzanejad;K. Tran;M. McVay;D. Horhota;Scott J. Wasman
对于深基础的成功设计和施工来说，完整的支护材料的土壤/岩石变异性和特性的详细信息至关重要。传统的侵入式测试方法，如标准贯入试验（SPT）和锥形贯入试验（CPT），仅对设备尖端附近的少量土壤/岩石特性进行采样。基于地面的地震方法可以提供总体地下条件，但由于表面波的主导作用而限于浅深度。为了解决这个问题，我们提出了一种新的SPT-地震测试方法的深场地表征。在不同深度处由SPT冲击产生的地震波场由地面上的地震检波器的2D网格记录，并且由3D全波形反演（3D FWI）分析以提取地下材料性质。与由在地表面附近传播的表面波主导的基于表面的波场不同，SPT地震波场富含从大深度传播的体波，其允许提取深度处的详细材料性质。用深源合成资料和标准贯入源野外资料对该方法进行了检验。综合实验结果表明，该方法能够成功地对具有隐伏异常的土壤分层进行成像。现场实验结果提供了新的见解，其效用作为一个可行的地球物理工具，深站点特性。三维地下S波和P波速度在9米的SPT钻孔周围的特点，包括两个深空在14-18米的深度。通过与基于表面的三维FWI方法的对比，证明了该方法在深部构造成像方面的优越性。最后反演结果的S波速度值也与SPT N值进行了比较，在整个深度上观察到了良好的总体一致性。
Detailed information of soil/rock variability and properties for the entire volume of supporting materials is crucial for the successful design and construction of deep foundations. Traditional invasive testing methods such as the standard penetration test (SPT) and the cone penetrometer test (CPT) only sample a small volume of soil/rock properties near the device's tip. Surface-based seismic methods can provide overall subsurface conditions but are limited to shallow depths due to the dominancy of surface waves. To address this issue, we present a novel SPT-seismic testing method for deep site characterization. Seismic wavefields generated by SPT blows at various depths are recorded by a 2D grid of geophones on the ground surface, and analyzed by a 3D full-waveform inversion (3D FWI) to extract subsurface material properties. Unlike surface-based wavefields dominated by surface waves propagating near the ground surface, the SPT-seismic wavefields are rich in body waves propagating from great depths that allow extracting detailed material properties at depths. The method is tested on in-depth source synthetic data and SPT-source field data. The results of the synthetic experiment indicate that the method successfully images soil layering with a buried anomaly. Field experiment results provide new insights into its utility as a viable geophysical tool for deep site characterization. 3D subsurface S-wave and P-wave velocities within 9 m around the SPT boring are well characterized, including two deep voids at 14–18 m depth. Comparison with the surface-based 3D FWI method proves the superiority of the presented method in imaging deep structures. S-wave velocity values of the final inverted result are also compared with SPT N-values and a good overall agreement over the whole depth is observed.