What are the steps for foundation treatment in gravity dams?
In order to prevent seepage through foundation, trenches may be excavated near heal of the dam and filled with cement concrete. Holes are drilled covering whole of the foundation and filled with cement grout. If the foundation is to be treated for large depths, the holes are also drilled for large depth.
Which foundation is not fit for concrete gravity dam?
Which foundation is not fit for concrete gravity dam or for rock-fill dams? Explanation: Due to enormous settlement, unconsolidated and high moisture clays are not fit for concrete gravity dams or for rock-fill dams. It can be accepted for earthen dams but only after special treatment.
What is the foundation of a dam?
DAM FOUNDATIONS. Concrete dams are constructed on rock foundations because of their enormous weight. Rock foundations have a very large load bearing capacity, resist erosion, and reduce permeability. A soil with a high permeability allows water to flow underneath the dam.
What is the maximum height suitable for silt and fine sand foundation for gravity dam?
Silt and Fine Sand Foundation: Silt and fine sand foundation is suitable for earth dams or very low gravity dams(up to height of 8 m).
What are the advantages of gravity dam?
Advantages of gravity dams.
- Gravity dams are relatively more strong and stable than earth dams.
- Gravity dams are well adapted for use as an overflow spillway crest.
- They can be constructed of any height, provided suitable foundations are available to bear the stresses.
How does a gravity dam work?
A concrete gravity dam has a triangular cross section with the base much wider than the crest. The dam is configured to provide enough mass and a sufficiently wide base to resist sliding and overturning in response to the force of water pushing against it.
What is highest gravity dam?
The Grande Dixence Dam
The Grande Dixence Dam, at a height of 285 metres, is the highest gravity dam in the world. Construction took 10 years, from 1951 to 1961.
What is the advantage of gravity dam?
Advantages of Gravity Dams The gravity dams possess the following advantages: These are more suitable in steep valleys where earth dams may tend to slip. In these dams, surplus water may be discharged through the sluices provided in the body of the dam or over spillway built in a suitable location of the dam.
Do dams have foundations?
A dam is built on a soil or rock foundation, depending on the type of dam. The foundation must be strong enough to carry the weight of the dam, and the water pressures acting on the dam. The dam foundation is below the original ground level. Some rock foundations have cracks and fissures in them.
Which dam has strong foundation?
Gravity dams generally require stiff rock foundations of high bearing strength (slightly weathered to fresh), although in rare cases, they have been built on soil foundations. The bearing strength of the foundation limits the allowable position of the resultant force, influencing the overall stability.
What are the disadvantages of gravity dam?
Disadvantages of Gravity Dams
- Their initial cost of construction is high.
- Their construction period is comparatively more.
- These require a strong and sound foundation.
- Dams once constructed, cannot be raised further.
- For the supervision of concrete dams, skilled labor is required.
How do you build a gravity dam?
Design. Gravity dams are built by first cutting away a large part of the land in one section of a river, allowing water to fill the space and be stored. Once the land has been cut away, the soil has to be tested to make sure it can support the weight of the dam and the water.
Where is the best place to build a gravity dam?
They can be constructed with ease on any dam site, where a natural foundation strong enough to bear the enormous weight of the dam is available. A suitable foundation for a gravity dam such as a sound rock foundation should be available. The river-valley at the dam site should preferably have a narrow gorge to reduce the dam.
What are the assumptions for a gravity dam?
In the case of gravity Dams on rock founda tions, a failure plane shall be assumed between the dam and the foundation. In addi tion, the potential for failure planes in the rock below the dam must be considered. Staff review of assumptions concerni ng uplift reduction should always be conservative.
What kind of foundation is needed for RCC dams?
This paper describes the foundation preparation work carried for two RCC Dams—one with a traditional gravity section and one with symmetrical section where the rock was judged to be of such quality that the traditional gravity section is deemed unsuitable.
How are deep set sluices used in gravity dams?
Deep-set sluices can be used in gravity dam, to retard the sedimentation or silt deposit in the reservoir. Gravity dams can be built only on a sound rock foundation.