The Research of Seismic Elastic Wave Reverse-time Migration Imaging Based on Tunnel Space

摘要

This paper provides a full 2-D elastic reverse time migration algorithm to predict unfavorable geological structures in front of the tunnel face in advance,in which we start from 2D velocity-stress equation and then use P wave and S wave decoupling staggered grid reverse time migration operator without converted wave and exciting time imaging condition.The migration of geological models shows ①Using pre-stack reverse time migration,we can obtain great migration images of the geological tunnel-based models,②When considering a vertical (the angle between interface and tunnel face) geological interface or a cave model,sidewall system with shots on the tunnel face contributes to migration imaging.③ In sidewall system,with the decreasing of the dip of geology interface,the energy of P wave migration increases while the energy of S wave migration decreases.Large dip contributes to S wave migration while small dip contributes to P wave migration.