Abstract: Compared with Rayleigh waves, Love waves exhibit a higher degree of frequency-dispersion curve identification, are free from P-wave interference, and present an easily recognizable dispersion curve shape. Applying Love waves to the detection of adverse geological conditions improves the accuracy of geological investigations. In this study, surface seismic source-induced Love waves are introduced into shallow surface geological exploration. First, the seismic records and dispersion curves of surface waves in front of a tunnel are analyzed to reveal the characteristics of Love wave signals in tunnel geological detection, and an extraction method for Love waves under complex urban environmental conditions is examined. Second, the inversion method for the Love wave dispersion curve is investigated, and a simulation example demonstrates the effectiveness of the damping least-squares method in fitting the Love wave dispersion curve. Based on this approach, a detailed detection method for tunnel construction in adverse geological conditions using Love waves is developed. Finally, a typical numerical model of adverse geological conditions in tunnel construction is established, and numerical experiments for Love wave detection are conducted. The imaging results show that face wave detection based on Love waves can accurately reflect changes in geological strata, enabling imaging and identification of typical formations such as layered strata with low-velocity interlayers and layered strata with low-velocity anomaly zones. A field test conducted in an urban area of Jinan verifies the effectiveness of the proposed method.

Key words: tunnel, unfavorable geology, Love surface wave, seismic record, dispersion curve characteristics, geological detection