面波产生的地震动转动分量的试验验证

EXPERIMENTAL VERIFICATION OF ROTATIONAL COMPONENTS OF EARTHQUAKE MOTIONS DERIVED FROM SURFACE WAVES

迄今为止,地面运动转动分量主要是通过弹性波动理论方法间接由平动分量获得,但并未得到证实。首次运用面波试验验证了这种求取转动分量的方法的合理性。重锤击落地面,在半无限空间弹性介质的地表附近,可产生面波(瑞利波和乐夫波),合理布置拾振器位置,测得产生面波的时程,利用两点差原理可以测得地面近似转动分量;将实测转动分量和用理论方法求得的转动分量的时程曲线以及傅立叶谱进行对比,由两种方法得到的转动分量加速度时程在振动持续时间内的开始阶段、强震阶段和衰减阶段基本一致;Fourier谱峰值、峰值点个数、峰值出现的位置以及谱曲线的形状走向是接近的。

At present, the rotational components of earthquake motions are mainly obtained from the translational components based on the theory of elastic wave propagation. However, this method has not been confirmed by strong motion observations. Surface wave experiment was used to verify the theoretical method. The results show that the method to calculate the rotational components is rational and effective. The experiment was conducted using ground hammering. The ground was assumed to be elastic semi-infinite space. The surface waves （Rayleigh wave and Love wave） were derived at the ground surface using measuring equipments at different locations. The rotational components could then be obtained approximately using deferential method. Comparing between the experimental results and the theoretical ones using the time histories and Fourier spectra, it is concluded that the acceleration time histories in the two approaches were consistent in the full range of earthquake motion, and the amplitudes, the number of peak and the shapes of the spectra are also close to each other for the Fourier spectra.