Application of High-energy Cosmic Ray Muon Imaging Technology in Shield Tunnels

Aiming at the technical challenges of detecting geological anomalies in the overburden strata and early warning of geological hazards during shield tunnel construction, a field test study of muon imaging technology is carried out in a typical shield tunnel project in Shenzhen. By deploying multiple muon detector arrays and applying an improved iterative density reconstruction algorithm, a high-resolution three-dimensional density structure model of the test area is established, enabling accurate localization of density anomalies in the strata. The results show that: (1) this technology can effectively identify density anomalies in geological bodies with a scale of 1-3 m; (2) in the shield-ahead detection mode, the density inversion sensitivity reaches 2%, allowing clear distinction of the physical boundary between moderately weathered and strongly weathered rock; (3) for a tunnel with a burial depth of 18 m, underground cavities with a width of approximately 4 m located 2-4 m above the tunnel crown can be accurately detected (positioning error <2 m), and the enhanced compactness after grouting reinforcement can be verified.