摘要
自由表面边界条件是决定瑞雷波数值模拟效果的关键因素。本文基于标准交错网格高阶有限差分法,在二维各向同性弹性介质背景下,针对应力镜像法(SIM)、改进应力镜像法(MSIM)、横向各向同性介质替换法(MS)和声学—弹性边界近似法(AEA)等四种最具代表性的自由表面边界条件进行了数值模拟,并在均匀半空间模型中从波场快照、波形曲线和频散曲线三个角度进行了对比分析。在相同条件下,上述四种方法均能生成符合勘探地球物理规律的波场快照,各自对应的数值解与解析解的拟合误差都随网格剖分精度的提高而减小,SIM和AEA数值模拟的稳定性和精度都明显高于MSIM和MS。基于层状介质模型的进一步研究表明:对于简单模型,SIM和AEA都能得到比MSIM和MS更高精度的数值模拟结果;对于复杂模型,AEA的精度最高,是最适合瑞雷波数值模拟的自由表面边界条件。
The free-surface boundary condition is a key factor of Rayleigh waves modeling.Under the condition of two-dimensional isotropic elastic medium and based on standard staggered-grid high-order finite difference algorithm,we simulate numerically the four most used free-surface boundary conditions:the stress image method(SIM),the modified stress image method(MSIM),the transversely isotropic medium substitution approach(MS),and the acoustic-elastic boundary approach(AEA).We compare their snapshot,waveform curves,and dispersion curves in a homogeneous half-space model.Under the same conditions,snapshots generated by four methods obey laws of physics.Their fit errors of analytical solutions and numerical solutions decrease with the increase of the grid subdivision.The stability and the numerical simulation accuracy of the SIM and AEA are significantly higher than that of MSIM and MS.For simple models,SIM and AEA achieve results with higher precision than the other two.However,AEA obtains the best results,which means it is the most suitable for the Rayleigh waves modeling.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2017年第6期1156-1169,共14页
Oil Geophysical Prospecting
基金
国家自然科学基金项目(41574114
41174113)
中国地质大学(武汉)教学实验室开放基金项目(SKJ2016098)联合资助
关键词
瑞雷波
有限差分模拟
自由表面边界条件
应力镜像法
声学—弹性边界近似法
Rayleigh wave
finite-difference modeling
free-surface boundary condition
stress image method
acoustic-elastic boundary approach
