Unformatted text preview: CEG 4012 ‐ Extra Credit Project (4 pts) Due on Mon, Dec. 5th 2011 An old mine was recently reopened and will start to produce ore soon. There is an existing tailings dam on the property but it is already full 1 m below the crest. The existing dam will need to be raised to accommodate the new production of ore. The height will be raised in three stages as shown in the table: STAGE CREST ELEVATION (m) 1 241 2 244 3 247 The dam will be raised using the downstream method of construction as shown on the figure. The current crest elevation is 239 m. The crest should maintain a width of 8 m for each stage. The initial project design requires a 3:1 upstream slopes and 2.5:1 downstream slopes. Each stage will be built with the same material as the original dam (coarse rockfill). The material properties for the dam, tailings and the soil underneath the dam are shown in the table: Material Name Unit Weight
(kN/m3) c Phi (kPa) (degrees) Coarse Rockfill 19 0 45 Tailings 16 0 27 Sandy Silt 21 0 31 Bedrock 27 1000 45 Clayey Silt 19.5 0 29 The engineering design criteria requires a minimum factor of safety of 1.5. Analyze the stability of each stage using SLOPE/W (because of the number of materials, you will need use the full version that is available in the computer lab.) and verify if each is safe. If they are not safe, improve the stability. For economic considerations, minimum slope angle is requested. *Remember: Tailings are saturated materials so a phreatic surface should be used on the models. The tailings level should be kept 1 m below the crest for each stage. Assume the dam has a toe drain to collect the seepage through the dam. The collection ditch on the DS side of the dam will collect any seepage that comes out of the dam. Turn in the output files from your analyses (print on landscape layout) with a brief report describing the project and your analyses and solutions Be aware: There are infinite numbers of solutions, so it’s almost impossible to get two identical! ...
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- Fall '08
- Harshad number, Prime number, clayey silt, Sandy Silt, Tailings Dam