Abstract
The accurate prediction of the geological conditions ahead of a tunnel plays an important role in tunnel construction. Among all forward geological prospecting methods, the seismic detection method is widely applied. However, due to the characteristics of the tunnel and the complexity of the geological conditions, the seismic wavefield is complicated. Carrying out a more realistic forward modeling method is vital for fully understanding the law of seismic wave propagation and the characteristics of seismic wavefield in the tunnel. In this paper, the 3D staggered-grid finite-difference scheme in the cylindrical coordinate system based on the decoupled nonconversion elastic wave equation is used to carry out the numerical simulation. This method can avoid the diffraction interferences produced at the edges of the tunnel face in the Cartesian coordinate system. Based on this forward modeling method, the characteristics of wavefield and propagation laws of seismic waves under three kinds of common typical unfavorable geological models were explored, which can provide theoretical guidance to seismic data interpretation of tunnel seismic forward prospecting in practice.
Highlights
Published: 24 June 2021The accurate prediction of the geological conditions in front of the tunnel during construction is critical
Due to the geological interfaces caused by excavation between the tunnel cavity and the surrounding rock, and the complex geological conditions in front of the tunnel, the seismic wavefield is complex, which leads to difficulty of the interpretation of seismic data
To better the propagation of the seismic wave and the characteristics of its wavefield, we carried out numerical experiments on the typical unfavorable geological models based on the decoupled nonconversion elastic wave equation
Summary
The accurate prediction of the geological conditions in front of the tunnel during construction is critical. The tunnel seismic forward prospecting is one of the mainstream methods in the current tunnel forward geological prospecting [1]. At the geological interfaces, which are subsequently received by the receivers arranged on the tunnel. By data processing methods, such as migration and inversion methods, the geological conditions in front of the tunnel can be obtained. Due to the geological interfaces caused by excavation between the tunnel cavity and the surrounding rock, and the complex geological conditions in front of the tunnel, the seismic wavefield is complex, which leads to difficulty of the interpretation of seismic data. It is of great significance to study the characteristics of seismic wavefield and propagation laws under different unfavorable geological conditions
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