【作者】 朱辉；

【导师】 李忠生；

【作者基本信息】 长安大学 ， 固体地球物理学， 2010， 硕士

【摘要】 近年来,随着城市建设进程加快,促进了工程勘探的应用和快速发展。工程勘探中的目标体一般较浅,地质情况较复杂,因此要求有精确的方法来模拟真实地下波场的传播规律,以便更好地了解浅层地质体的特征。为了提高地震波数值模拟精度,在前人工作的基础上,本文采用了时间二阶、空间十阶的高阶有限差分方法,来进行数值模拟及波场特征分析。在工程勘探中,地下介质可以近似看成是完全弹性和各向同性的。文中首先介绍了地震波数值模拟的理论方法及高阶有限差分法在其中的应用,然后针对完全弹性和各向同性介质中的声波和弹性波的一阶速度—应力方程,利用交错网格技术,通过Taylor展开和有限差分,详细推导出了它们的高阶差分格式；对工程上常遇到的地质模型,分别用声波和弹性波进行数值模拟,从模拟得到的波场快照和炮记录中分析地震波在地下介质中的反射、折射、透射、绕射以及能量的衰减等运动学和动力学的各种特征。结果表明：交错网格高阶有限差分波场数值模拟具有较高的精度,计算速度快,基本能满足工程上的需要。在文章的最后部分,结合实际地质情况,建立理论模型,利用文中推导的模拟方法对该模型进行正演,得出地震波在地下地质体中的传播情况,与采集资料作对比分析,了解折射波、反射波、绕射波等的概况,再对实际资料进行处理,以达到提高解释精度的目的。更多还原

【Abstract】 Recently, as the rapid development of city construction, the application of engineering exploration has developed rapidly. In engineering exploration, the objects are shallow and the geological condition is complex, so it is necessary to develop an accurate method to simulate the seismic wave propagation in real media of subsurface in order to research the characteristics of shallow geological body. To increase the accuracy of seismic wave modeling, this paper uses high-order finite-difference of second-order in time and tenth-order in space to simulate and then analyze seismic wave characteristics based on the previous study.In engineering exploration, subsurface media are regarded as perfectly elastic and isotropy. Firstly, the theory of seismic wave numerical simulation and its application using high-order finite-difference method are introduced. Then the high-order finite-difference schemes of acoustic and elastic velocity-stress equation in perfectly elastic and isotropy media are derived using staggered-grid method. The paper simulates the geological models which will be encountered in engineering exploration using the acoustic wave equation and elastic wave equation respectively, and analyzes the characteristic of kinematics and dynamics such as reflection, refraction, transmission, diffraction and the attenuation of energy of seismic wave from the snapshots and shot-records produced from the simulation. The results show that the staggered-grid high-order finite-difference method can satisfy the demands of engineering with high accuracy and rapid computation.In the last part of paper, the models with real geological condition are created and then are simulated using the modeling method derived in the paper above to research the seismic wave propagation of subsurface. Then I analyze the seismic wave propagation characteristics of refraction, reflection and diffraction comparing with the collected data in order to increase the accuracy of interpretation.更多还原