MESH DEPENDENCY IN NUMERIC MODELING FOR DETERMINATION OF THE FAILURE ZONE THICKNESS AROUND THE TUNNEL BASED ON HOEK BROWN CRITERIA
The crush zone is an important component that can be used to assess and treat opening holes. The thickness of such crushed zones can be modeled using the finite element method in RS2 software. The modeling results obtained depend on the mesh used. Modeling was carried out on fair and very poor ro...
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| Format: | Final Project |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/66466 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | The crush zone is an important component that can be used to assess and treat opening holes. The thickness of such crushed zones can be modeled using the finite element method in RS2 software. The modeling results obtained depend on the mesh used.
Modeling was carried out on fair and very poor rock masses with a depth of 500 m with factor values k 1 and 2 in tunnels 4 m in diameter. The analysis is carried out by varying the number of points around the tunnel with the shape of the selected element in the form of a triangle with the number of points 3. The number of points around the tunnel is 25 to 400 in multiples of 25. From the number of points, it produces the total number of points and the number of elements in different modeling – the difference that the greater the number of points around the tunnel the greater the number of points of the whole and the number of elements in the modeling.
The value of the crush zone in the tunnel depends on the number of elements and the number of points (nodes) used in the tunnel modeling. The relationship between the average and mesh crush zones fluctuates and does not continue to rise as the number of elements and points increases, but there is a tendency for the crush zone to increase as the number of elements and the number of points increase. The weaker the rock the greater the value of the crushed zone that will be produced. This can be seen from the mass of very poor rocks that have a large hacur zone compared to the fair rock mass, both at k=1 and k=2, the most massive crushed zone is found on the roof and floor. The relationship between the crush zone and the number of elements is best in modeling the mass of fair rocks with a factor value k = 2 resulting in a correlation coefficient of 0.928. |
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