高阶交错网格和PML吸收边界在横向各向同性介质地震波场模拟中的应用  

THE APPLICATION OF PML BOUNDARY CODITIONS IN THE SIMULATION OF SEISMIC WAVE BY THE HIGH-ORDER STAGGERED-GRID FINITE DIFFERENCES AT THE TRANSVERSELY ISOTROPIC MEDIA

作　　者：陈洁 朱守彪[1] CHEN Jie;ZHU Shou-biao(Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China)

机构地区：[1]中国地震局地壳应力研究所,地壳动力学重点实验室,北京100085

出　　处：《地震地质》2020年第3期654-669,共16页Seismology and Geology

基　　金：国家自然科学基金(41874060);国家重点研发计划项目(2017YFC1500104);中国地震局地壳应力研究所基本科研业务专项(ZDJ2020-15)共同资助。

摘　　要：完全匹配层吸收边界条件通常可以很好地吸收模型边界的地震反射波,但对于横向各向同性介质的模拟效果欠佳,且尚在发展阶段。为此,文中推导了横向各向同性介质中弹性动力学波动方程,给出了施加完全匹配层(PML)吸收边界条件下时间域二阶、空间域十阶精度的高阶交错网格的有限差分形式,并分别建立了均匀的垂直向对称轴的横向各向同性介质(VTI介质)和倾斜向对称轴的横向各向同性介质(TTI介质)模型。计算结果表明,对于对称轴为任意角度的横向各向同性介质,当PML边界层厚度达到一定的数值时,可以很好地抑制人工边界所产生的地震波反射效应,且PML的吸收效果不会被入射角与入射波频率影响。In the realm of the numerical simulation,finite difference method and finite element method are more intuitive and effective than other simulation methods.In the process of simulating seismic wave propagation,the finite differences method is widely used because of its high computational efficiency and the advantage of the algorithm is more efficient.With the demand of precision,more and more researchers have proposed more effective methods of finite differences,such as the high-order staggered-grid finite differences method,which can restore the actual process of wave propagation on the premise of ensuring accuracy and improving the efficiency of operation.In the past numerical simulation of seismic wave field,different models of isotropic medium are mostly used,but it is difficult to reflect the true layer situation.With the research demand of natural seismology and seismic exploration,the research on anisotropic media is more and more extensive.Transversely isotropic(TI)media can well simulate the seismic wave propagation in the formation medium,such as gas-bearing sandstone,mudstone,shale et al.,the character of TI media is reflected by introducing the Thomsen parameters to reflect its weak anisotropy of vertical direction by using Thomson parameter.Therefore,studying the process of seismic wave propagation in TI media can restore the true information of the formation to the greatest extent,and provide a more reliable simulation basis for the numerical simulation of seismic wave propagation.In the geodynamic simulation and the numerical simulation of the seismic wave field,under the limited influence of the calculation area,if no boundary conditions are added,a strong artificial boundary reflection will be generated,which greatly reduces the validity of the simulation.In order to minimize the influence of model boundaries on the reflection of seismic waves,it is often necessary to introduce absorbing boundary conditions.At present,there are three types of absorption boundary conditions:one-way wave absorption

关 键 词：完全匹配层 吸收边界条件 横向各向同性介质 高阶交错网格 有限差分 

分 类 号：P315.31[天文地球—地震学]