Big Construction Project: Three Gorges Dam - Discussions

hey super😁
It's wonderful to discuss the constructions of such big projects.hoping to learn more through the discussions in here 😁

ok here are some points i just learned

That area is a typical weak-earthquake area geologically.Even if an earthquake occurred, that earthquake would be a very weak quake with low frequency.this is because the base is a hard surface made of frequent magma flows in the centuries back.it has high mechanical strength(100 MPa).

The rock bodies at the dam site of the Three Gorges Project are of extremely weak hydraulic conductivity. so the base is water proof and prevents any seepage of water.

The TGP dam is a concrete gravity one, made of 14.86 million m3 concrete, the biggest amount in the world. The maximum flood discharge capacity of the dam is 116 ,110 m3/s, biggest in the world.it used 463,000 tonnes of steel, enough to build 63 Eiffel Towers.

and here is a video i found to be quite useful in understanding the history of the dam.

[video=youtube;-NUycoFY_00]https://www.youtube.com/watch?v=-NUycoFY_00[/video]

waiting for more points and interesting facts 😁

Alrighty, good information. Can anyone here list out the most important factors civil engineers consider before designing the dam?

yeah. i can list a few.but mind you i'm just in my second year and can make a lot of mistakes.just trying to put forth some points learnt last semester in my applied geology.

1.the dam should be built in the course of the river at a point where it's width is less.

2.the site should be as sturdy as possible and should be made of strong, impermeable rocks

3.the materials should be available close by.it will reduce the cost to some extent.but this is not the most important factor.

4.all dams do cause the environmental hazards like loss of cultivable land, loss of forests,etc. but a dam should be designed to reduce the impacts on environment.

5.the dip of the surface should also be studied.

6.and the dam should never be built on a area where there are folds.(shown in the figure below. the anticlines and synclines are folds).it leads to the movement of the structure

7.the dam should not be built on the area of fault.fault is the breaking of the earth surface.it will lead to the seepage of water into the earth.
there should also be no joints.
the four main faults are shown in the figure below.
the dam should not be built on these area.but if it is absolutely necessary to build a dam in that spot.we have to build it only in a reverse fault region with the fault along downstream direction .



that's all i could recollect.will get back with more points😁

all the information provided by CP is right. the main criteria for dam construction is the strength of foundation. it should be strong, hard and impervious. For any major civil engineering construction, we should consider the geological structures.
They are:
1. folds
2. faults
3. joints
4. unconformities
these play a major role in constructions.
(correct me if I'm wrong)

hey madugula 😀

what do you mean by unconfirmities. :?:
i have not studied that term. is it something like the faults 😕

These "extreme" engineering projects are quite interesting. Can't wait until engineers construct the Bering Straight crossing, or the underground Atlantic super train tunnel.

As with a majority of dam projects, there are impacts to people and environment. Its unfortunate that people will still have to be relocated and farms destroyed. Hopefully they are compensated justly. Aside from the electrical production, the future flood control would be welcoming.

CIVILPRINCESShey madugula 😀

what do you mean by unconfirmities. :?:
i have not studied that term. is it something like the faults 😕

it is totally different from folds, faults and joints. if a major break occurs in a sedimentary rock, then the chronological sequence of the sedimentation gets disturbed.
so unconformity means a period of 'non deposition' and acts as a plane of contact between two sets of conformable beds.
Unconformities in rocks occur due to upliftment and subsidence of land mass.
however these dont show much effect on dams and other civil projects.

oh ok i get it.
Thanks😁

Interesting. Thank you Biggie for starting this thread and to Civil Princess and Madugula for widening our knowledge.