Chronicles and prospects of tunnel seismic prognosis

Abstract This paper provides a systematic review and envisions of the development of seismic techniques for forward prognosis ahead of a tunnel face. Early seismic exploration in tunnels began with the use of the active source. Seismic techniques such as tunnel seismic prediction, horizontal sound probing, tunnel reflector tracing, and seismic ahead prospecting were developed. In contrast to the vertical seismic profiling in classic seismic exploration, these tunnel seismic methods using an active source can be collectively called horizontal seismic profiling (HSP). Over recent decades, the tunnel boring machine (TBM) has been widely used as the primary method for tunnel excavation due to its high efficiency. The noise generated by TBM operation can be used as a seismic source to illuminate the earth for geological characterization with the significant advantage of least interruption to the tunneling process. This approach, known as tunnel seismic while drilling (TSWD), is inherited from seismic while drilling (SWD) in exploration seismics. After reviewing all pertinent seismic techniques and discussing the respective pros and cons of HSP, SWD, and TSWD, we propose a more comprehensive approach for seismic formation prognosis in front of the tunnel face acronymized as tunnel seismic prognosis while drilling (TSPWD) to emphasize prognosis (comprehensive diagnosis and treatment) of the geological averseness. TSPWD aims to generate better imaging based on all kinds of information from arrays inside and outside of the tunnel, generated from all kinds of seismic sources, other geophysical surveys, and the TBM operation parameter via AI deep-learning.