盆地构造地震地面运动速度和加速度分布特征的数值模拟

本文用错格实数傅里叶变换的拟谱法的数值模拟方法分析了地震波在冲积扇、盆地等不均匀地震构造体区域的传播过程和地面运动分布. 结果表明, 地震波由岩石区进入盆地结构后，在盆地内上下多次反射振荡，对地面建筑物可能形成多次连续的振动和破坏，仅有极少量地震波能量返回岩石区域中，这是防灾研究中值得注意的地面运动特征；地震波在盆地边界地质构造条件下，形成的地震波体波与次生面波动的叠加干涉形成了大振幅的地面运动，它可能导致建筑物的极大破坏；破坏峰值的空间位置可能远离岩石和盆地沉积层的边界或者地震断层的位置.

Velocity and acceleration characteristics of seismic ground motions related to basin structure

In present analysis distributions of seismic wave propagation and amplitude related to basin structure and alluvial fan in heterogeneous medium are digitally simulated by using the pseudospectral method with the staggered grid RFFT differentiation. The results show that the seismic energy transmitting into sediments in the basin from the bedrock region can not penetrate the bottom of basin back into the bedrock region. The seismic waves oscillating up_down within the basin may result in large damages for buildings above the basin structure. It is a notable characteristic for the aseismic research and engineering. Interferences due to the secondary surface wave from the bedrock to sedimentary basin and the upward body wave probably result in peak ground accelerations and peak collapse ratios of buildings away from the earthquake fault. Analyses of the interference process show that seismic velocity structure and geologic structure strongly influence the distribution of the maximum amplitudes of acceleration and velocity waveforms.