STUDY ON SIMULATION OF SEISMIC WAVE TRAVEL TIME IN TUNNEL ADVANCED GEOLOGICAL PREDICTION USING REFLECTION WAVE METHOD

Tunnel construction safety often faces enormous challenges due to complex geological conditions. Reflection wave seismic exploration has the advantages of a large detection depth and strong anti-interference ability, making it an important advanced geological prediction method to ensure tunnel construction safety. The calculation of reflected seismic wave travel time is closely related to multiple steps in seismic data processing, such as the separation of longitudinal and transverse waves, velocity modeling, and migration imaging, which directly affect the results of tunnel geological prediction. This article will simulate the actual construction area of advanced geological prediction for tunnels using the reflected wave method for velocity modeling. Based on solving the functional equation, combined with the upwind finite difference method and narrowband expansion technology in the Fast Moving Method(FMM), the first break seismic wave travel time simulation for the tunnel model will be achieved. By extracting the location information of the reflection interface in the tunnel model, an initial narrow band of the reflection wave is constructed, and, combined with narrowband expansion technology, the calculation of the travel time of the reflection wave in the tunnel model is achieved. Through numerical analysis and complex tunnel model calculations, it is shown that the reflected wave method proposed in the article has good computational accuracy and strong adaptability in predicting seismic wave travel time in the advanced geological prediction of tunnels.