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5 Cards in this Set
- Front
- Back
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Why underground powerhouse? |
* No proper site on the ground to place the hydropower station * Good geological condition * Requirement of the National defense |
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Advantages & Disadvantage of underground |
Advantages * Benefit the layout of other hydraulic structures. * Avoid the threat of landslide * May decrease the economic investment. * Avoid the influence of rain, temperature and other factors during construction * Keep the ground landscape Disadvantages * Large amount excavation * Not good in ventilation, dehumidification * Additional investment on support structure |
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Types of diversion underground powerhouse |
1. Head type * Integral rock in the head part *Limestone in the tail part (karst cave) *Short pressure tunnel * long tail water tunnel *No surge chamber in upstream
*Near the reservoir, the seepage control *High head condition, , wire outlet, and ventilation,
*the depth is too large * hard for construction and operation *expensive in traffic
2. Tailtype- Popular type *Long pressure tunnel *short tail water tunnel *Surge chamber in upstream *Traffic and construction of power house is easy *Fit for high water head Disadvantage: low elevation, not good for the pressure trunnel
70% of underground power house in China are this type.
3.Middle type * Long pressure tunnel and long tail water tunnel * Usually have surge chambers in upstream and downstream |
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Caverns in underground powerhouse |
1. Traffic cavern: * usually horizontal, in special condition vertical, * connected with the assembly place * Besides the traffic cavern, there must be the other outlet cavern for the safety.
2.Main cavern *Avoid longitude axis in line with the major dislocation *Vertical to the strike of the rock layers * In line with the direction of the maximum principle stress( if not, angle < 30 degree)
3. Assembly place * In the longitude side of the main cavern or in the middle * The rock under the assembly place could be kept for the safety of the cavern
4. Auxiliary cavern * Usually in the longitude side of the main cavern, in one cavern with the main cavern * Some rooms on the ground to decrease the size of the cavern
5.Main transformer *Usually underground, for short busbar *Ventilation, smoke discharge, fire prevention, anti-explosion
6. Two choices *Unique cavern, parallel to the main cavern * In the longitude side of the main cavern
7. High voltage switchyard Usually on the ground, connected with the main transformer cavern by vertical well or oblique well
8. Valve cavern: * in the main cavern, or above the valve when outside
9. Tail water gate cavern, and tail water tunnel * Design a well connect the gate cavern and the draft tube
10. Ventilation cavern *Including intake cavern, outlet cavern, and fan room * The fan room must be far away from other rooms (noise)Usually the traffic cavern are used as ventilation cavern |
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Layout of caverns |
*Minimum depth 1.5-3.0 times to the width of the cavern
*Horizontal distance between caverns 1.0-1.5 times to the larger width of two caverns *Cross of caverns Perpendicular
*Vertical distance between caverns 1-2 times to the width of the cavern -The layout of different caverns should be together - The rock between draft tube, between draft tube and the busbar cavern should be thick enough, using narrow and high draft tube |
