【摘要】 本文在总结前人研究成果的基础上着重描述了通过密集强震台阵观测到的地震动空间变化的特征,阐明了工程方法在研究地震动场时所面临的困难和其自身的缺陷。随后从震源和地震波在真实介质中传播这两方面考虑,提出了用参考点地震动和表示台阵内各台点几何关系、介质特性以及震源影响的Fourier谱矩阵所描述的地震动随机场理论。这一理论的核心在于一方面用参考点的地震动近似表示整个震源大小和传播介质在大范围的地质构造背景下对整个地震动场的影响、控制;另一方面用地震波的衰减、频散、地震波的入射方向以及等效相速度的随机涨落来刻画小范围内各个台点由于地震波的传播路径不同、各台点所处的场地条件不同而在地震动上产生的差异。最后利用SMART—1台阵的部分强震记录检验了本文方法的合理性。更多还原

【Abstract】 The paper first describes the space variation characteristics of seismic motion observed at dense arrays,then illuminates the difficulties and faults of engineering method in studying and modelling seismic motion field. A new physical framework for estimation of ground motion field is presented in the paper. It consists of two links: (1)estimating the ground motion at the referential point,which can be used to express the average effects of seismic source and regional geological background on the seismic motion field; (2)estimating the ground motion variation in a small area on the basis of the random disturbance of equivalent phase velocity and small -dimension Q value structure. Five earthquake data recorded at SMART-1 dense array are applied to test the physical model. The results show that the model is reasonable.更多还原