Topography and Anisotropy Adaptation of a Modified Discrete Element Method in Elastic Seismic Wave Modeling

Abstract:

Discrete element method (DEM) is a useful technique in dealing with discontinuum. By calculating the behavior of the particle system, DEM can simulate behavior of the object such as faulting and creeping. On the other hand, topography and anisotropy adaptation, which can be challenging for numerical algorithms, is of great significance in seismic wave modeling. During our research on DEM, we discovered that due to its special scheme of discretization, DEM is a highly flexible numerical method which can realize this adaptation. In our study, we conduct a proper modification to traditional discrete element method and apply this modified DEM to elastic seismic wave modeling. The accuracy of this numerical method is proven by comparing the displacement field obtained by our DEM and that from a finite difference method. Besides, we manage to develop a theory which enables us to simulate wave propagation in transverse isotropy (TI) media using our DEM. In addition, a simple mechanism is also established, making the modified DEM much more convenient to adapt complex free surface topography than other numerical methods, such as finite difference. Therefore, our research provides a new numerical method in seismic wave modeling that can handle both anisotropy and irregular topography.