High-Precision Forward Analysis and Field Test of Boulder Detection on Zero-Offset Elastic Wave Method in Shield Tunnel

Abstract

Efficient and accurate boulder detection technology is essential for shield tunneling safely under complex floodplain geological conditions. The traditional seismic reflection method is not suitable for complex geological conditions and small targets near the surface, the elastic wave reflection method based on zero-offset observation is proposed in this article. Forward is the basis of inversion, a high-order staggered grid finite difference algorithm based on least-squares optimization (LS-SGFD) is established, which has the advantages of higher accuracy and smaller dispersion. Three typical geological models are designed, and the elastic wave reflection characteristics of the method proposed in this paper and the traditional method are systematically analyzed. From the dual perspectives of field experiment and engineering application, the effectiveness of zero-offset observation for the detection of boulders is discussed, and the basic criteria for boulder identification are given. Research shows that this method has good results in detecting boulders on the surface, and it has certain reference significance for similar projects.