Advancements in 3D Subsurface Modeling Using Seismic Refraction Data
Publisher – EEGS, 2006. Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP) proceedings.
Phil Sirles*, Zonge Engineering and Research Organization, Inc., Denver, Colorado, U.S.A.
Alan Rock, Summit Peak Technologies, LLC.,
Khamis Haramy, Federal Highway Administration – Central Federal Lands Highway Division. U.S.A.
Paper – [pdf] INFR_Sirles_2006_Advancement in 3D subsurface modeling using seismic refraction data
Standard subsurface imaging using seismic refraction data produces two-dimensional (2D) images of the subsurface. Engineers and geologists (i.e., the end users) typically must integrate other subsurface data with results from a seismic investigation. Advancements in refraction data analysis have increased the ability to image geologic features and provide better 2D graphical presentation of refraction results. As refraction tomography increases the ability to meet project objectives and present 2D color images more representative of the subsurface, we begin to approach the end users’ needs. That is, the end product from a refraction survey can be either a 2D image or a full 3D model. Full 3D earth models can be used for many purposes after the geophysical survey is complete. Subsurface physical property data in 3D model space permits assessment of a site from a whole new perspective. For example: structural loading, seismic loading, or construction excavation requirements can be uniquely handled using 3D model results.
This paper presents an advanced approach to
refraction data processing, presentation, and visualization, using the “Geostructural Analysis Package” (GAP). GAP incorporates several numerical modeling processes: discrete element method, particle flow code, finite differencing, and the material point method. These four numerical modeling methods have been combined and optimized for seismic applications. GAP is an innovative tool that allows better data analysis and presentation that can be used to produce 3D volumetric models for further analysis. For example, mapping top-of-rock may be the objective of a geophysical investigation, but it is not the engineering purpose of the survey (e.g., construction of critical structures – a dam or a bridge foundation).
3D model results from two case histories are presented to demonstrate the benefit of processing and presenting seismic refraction data using a new perspective – GAP modeling. GAP represents the newest advancement in subsurface modeling using refraction data.