The excavation process in mechanized tunneling can be improved by reconnaissance of the geology ahead. A nondestructive exploration can be achieved in means of seismic imaging. A full waveform inversion approach, which works in the frequency domain, is investigated for the application in tunneling. The approach tries to minimize the difference of seismic records from field observations and from a discretized ground model by changing the ground properties. The final ground model might be a representation of the geology. The used elastic wave modeling approach is described as well as the application of convolutional perfectly matched layers. The proposed inversion scheme uses the discrete adjoint gradient method, a multi-scale approach as well as the L-BFGS method. Numerical parameters are identified as well as a validation of the forward wave modeling approach is performed in advance to the inversion of every example. Two-dimensional blind tests with two different ground scenarios and with two different source and receiver station configurations are performed and analyzed, where only the seismic records, the source functions and the ambient ground properties are provided. Finally, an inversion for a three-dimensional tunnel model is performed and analyzed for three different source and receiver station configurations.
翻译:机械化隧道的挖掘过程可以通过对前面地质学的勘察加以改进。在地震成像手段中可以实现非破坏性的勘探。在频域中使用的全波形反向方法,将调查用于隧道应用;该方法试图通过改变地面特性,将地震记录与实地观测和离散地面模型的差别降到最低。最后的地面模型可能是地质学的表示。使用的弹性波模型方法以及脉冲完全匹配的层的应用都得到了描述。拟议的反向方案使用离散连接梯度法、多尺度法以及L-BFGS方法。数字参数得到确定,对前波模型方法的验证工作在转换每个例子之前进行。用两种不同的地面假设和两种不同的源和接收站配置进行二维盲试验和分析,其中仅提供地震记录、源函数和周围地面特性。最后,为三个不同源和接收站配置进行三维隧道模型的反向分析。