Analysis of Propagation Characteristics of SH Waves in Upper Soil and Lower Rock Strata

In order to study the propagation law of blasting seismic waves in general strata induced by underground engineering constructions, shear horizontal (SH) waves were selected as the research object and the stiffness matrix and dynamic balance equation of general layered strata were established based on elastic wave theory. The propagation law of plane SH waves in the soil-rock stratum was studied, and the influence of soil-rock impedance ratio, thickness of soil layers, frequency and incident angle of incident waves on the ratio of ground velocity to soil-rock interface velocity |u₁/u₂| was analyzed. Results show that the peak |u₁/u₂| decreases with the increase of the frequency of incident waves, and the secondary peak is obviously smaller than the first peak. In practical engineering, the focus is on the first predominant frequency of the soil layer; as the impedance of the soil layer increases, the high-frequency response becomes stronger and stronger, and it is also increasingly affected by the incident angle. When the soil layer is thin, the high-frequency response of |u₁/u₂| is more obvious, but it becomes smaller and smaller as the thickness increases. This indicates that the high frequency filtering effect of the soil layer increases with the increase of the thickness.