A Staggered-Grid High-Order Finite Difference Numerical Simulation for Tunnel Seismic Prediction Ahead of Construction

For safe tunnel excavation, it is important to predict litho-logic and structural heterogeneities ahead of construction. To study generation mechanism and propagation rules of body wave that are directly generated on tunnel sidewalls or face, based on the one-order velocity-stress elastic wave equation, we deduced the staggered grid high order finite difference format. After constructing the tunneling conceptual models with such geological disasters as fault and gradient weak intercalation in underground engineering, we simulated the wave propagation with absorbing and impedance boundary conditions on external boundary, and free boundary on tunnel region boundary. By excitation-time imaging conditions we also implement reverse-time migration. The numerical simulation results show that the method was very simple, and can acquire the wave field characters and migration sections effectively and directly, which can offer logical proofs for tunnel seismic prediction ahead of construction.