Seismic Characterization of Tunnel Boring Machine Activity

Acoustic Resonances in the Tunnel?

Organ pipe modes in tunnel: nv/4l ; n = 1, 3, 5,...
Interval between modes: v/2l = 0.025 hz
(v = sound speed in air, .3km/s; l = distance from head of tunnel to shaft = 6.06 km)

Introduction | Spectrograms | Signal and Noise Spectra | TBM Signal Attentuation
Frequency-Wavenumber Analysis of the Mini-Array | Acoustic Resonances | Conclusions