Three-dimensional seismic ahead-prospecting method and application in TBM tunneling

摘要

The tunnel seismic ahead-prospecting method is used to estimate adverse geology ahead of the tunnel face. Accurately realizing this geology helps to guarantee safety during construction using a tunnel boring machine (TBM). The paper proposes a three-dimensional (3D) seismic ahead-prospecting method by optimizing a filtering method and an imaging algorithm. In this paper, a united filtering method based on f-k and t-p filtering is introduced. First, the waves from the interfaces behind the tunnel face are removed and P- and S-waves are separated. Then the interference waves are further eliminated by t-p filtering. Mirrored artifacts resulting from the equitravel time plane algorithm are suppressed by the directional weighting integrated into the algorithm. Imaging results indicate that the new method suppresses mirrored artifacts better and produces accurate results. Moreover, the improved algorithm produces reflections that are more consistent with the interfaces than those produced by the original algorithm without directional weighting. Field studies using the 3D seismic aheadprospecting method have accurately identified and located the main fractured zones, proving the reliability and superiority of the method.