Example Cost of 3-D FEM for Underground Openings

The use of three-dimensional finite element methods for the analysis of underground structures has been limited in practice, partially because of their supposed high costs. A more quantitative perspective on this issue is gained by examining the actual costs from one particular but typical study for the Peachtree Center Station cavern in Atlanta. The analysis simulated three excavation steps in high quality gneissic rock, which was modeled as a homogeneous, isotropic, elastic material. The cost of the analysis was approximately $18,000 for computer time and $20,000 for manpower, for a total of $38,000 or approximately 0.1% of the total project cost. Comments on the suitability of 3-D finite element analysis in the design process are also given.