Non-gradient full waveform inversion approaches for exploration during mechanized tunneling applied to surrogate laboratory measurements

摘要

Drilling into unknown soil during mechanized tunneling may cause damage of the tunnel boring machine or delays in the construction process. A full waveform inversion can prevent these issues supplying a detailed image of the subsoil, but claims several challenges like the need for an adequate method or the need for an appropriate utilization of seismic sources and receivers. In this research, a small-scale surrogate model is constructed in order to create representative tunneling field data in a laser laboratory. With the experimental model, ultrasonic data is generated. After constructing an adequate forward model, two non-gradient full waveform inversion methods based on parameter identification are applied to the measurement data in order to determine the inner structure of the model out of seismic waveforms. Furthermore, the positioning of seismic sources and receivers is investigated. The algorithms are found to perform well on the acquired measurement data, with different precisions dependent on the utilized method and on the source-receiver configuration. The comparability of the ultrasonic data to tunneling field data is analyzed.