关键词: 地震波, 围岩, 各向异性, 动参数, 结构面

Abstract: Based on the advanced geology forecast by seismic reflection method at Tingzhou Tunnel in Ganzhou-Longyan Railway, fifty-seven selected seismic records are used for investigation. Within the segments of excited seismic wave in the surrounding rock, the differences of the shear wave velocity in horizontal and vertical directions are analyzed statistically, separately. Additionally, the anisotropy of surrounding rock is also considered. It can be seen from the results that when the shear wave velocities in horizontal direction vary from in vertical direction, shear wave anisotropy presences in different degrees in the surrounding rock. Vertical shear wave velocities are generally higher than the horizontal ones, and the most of shear wave anisotropy coefficients are within ±10%. It is found that the anisotropy coefficients of dynamic elastic modulus, dynamic shear modulus and dynamic Poisson ratio are in the ranges from -15% to 15%, from -20% to 20%, from -20% to 15%, respectively. The anisotropy degree of surrounding rock depends on the grade of surrounding rock, seismic longitudinal wave velocity and the buried depth of tunnel. The anisotropy coefficient of shear wave and its discrete degree are relatively higher, when the seismic longitudinal wave velocities are between 3 800 and 5 000 meters per second or when the buried depth of tunnel is between 60 and 100 meters. Among the tests conducted on the surrounding rock of grades Ⅱ-Ⅴ, it is noted that the shear wave anisotropy and its discrete degree is the highest in surrounding rock of grade Ⅳ, but is the lowest in the surrounding rock of gradeⅡ.

Key words: seismic wave, surrounding rock, anisotropy, dynamic parameters, structure surface