DR - Large-Scale Geotechnical Model
Computations of stress changes due to uranium ore mining in the depth up to 1200 meters at the mine GEAM Dolni Rozinka (DR) in the Bohemian - Moravian Highlands (the Czech Republic). The computed stress changes are used for comparison of different mining methods in relation to a risk of dangerous rockbursts.
![](javascript:openpic("other/problem/dr-01.jpg", "en",
"DR - Situation and mesh", 500, 347 ))
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![](javascript:openpic("other/problem/dr-02.jpg", "en",
"DR - Results", 500, 398 ))
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The whole modelling simulates four stages of mining, represented by a four-step sequence of problems with different material distributions. The last situation is used as a benchmark problem for comparison of different linear system solvers.
Description
Elasticity problem in a domain of 1430 x 550 x 600 meters located 800 meters bellow the surface, loading by weight of overburden on the top domain face, symmetry plane boundary conditions on the other faces, weight of rocks, initial stress.
Discretization
Regular grid of 124 x 137 x 76 nodes, each brick is divided into six tetrahedra by Kuhn's type division. Linear tetrahedral finite elements results in a linear system with 3 873 264 DOF.
Times of parallel computing
Solution of the FEM system by two-level overlapping Schwarz method with minimal overlap, replacing of subdomain problems by incomplete factorization, creating of coarse grid problem by aggregation, approximate solution of the coarse grid problem by inner PCG iterations with relative accuracy eps=0.1. The FEM system is solved from the zero initial guess up to relative residual accuracy eps=0.0001.
The best computing times
| Computer | # Processors | Computing time [s] |
|---|---|---|
| Lomond | 8 | 251 |
| Simba | 20 | 70 |
| Thea | 8 | 103 |
| Termit | 20 | 40 |