Hoover dam: How it’s work and the engineering secrets of Hoover dam

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Hoover Dam: How it’s work

The magnificent Hoover dam: How it’s work which was constructed 80 years ago still stands strong and serves the u.s and the fields of irrigation flood control and power production

Hoover Dam: How it's work
Hoover Dam: How it’s work

 Even during a torrential rainfall you won’t see Hoover dam overflowing like this causing destruction welcome to the engineering secrets of Hoover dam: How it’s work.

Designer engineer Mr. John savage:

Hoover Dam: How it's work
Designer engineer Mr. John savage:
  • Colorado River
  • Black Canyon Mountains

You’re going to assume the role of Hoover dam designer engineer Mr. John savage and design and construct a gigantic dam in Arizona’s Colorado River Mr. John savage’s surveying team zeroed in on the black canyon mountains beside the Colorado River.

 the reason the mountains have a decent height and narrow gaps between them allowing for huge savings on construction materials however many design challenges were still ahead of the project’s chief engineer.

Hoover Dam: How it's work
black canyon mountains beside the Colorado River.
  • Straight concrete
  • Outer fibers and inner fibers
  • Downstream side and upstream side
Downstream side and upstream side
Downstream side and upstream side

let’s start with the design of a straight concrete wall of uniform width the strong water pressure obviously causes the wall to deform and bend you can observe that due to this bending the outer fibers become elongated and the inner fibers are compressed this scenario results in tension on the walls downstream side and compression on its upstream side when tensile stress is applied to concrete it easily develops cracks generally modern buildings use steel bars to overcome this issue as steel rods can readily carry a large tensile load.

The arch dam technology:

Points of paragraph:

  • A length reduction
  • Strong compression forces
  • Toppling due to the water pressure
The arch dam technology:
The arch dam technology:
Strong compression forces
Strong compression forces

 however Mr. john savage had a much simpler solution one that does not require steel rods the arch dam technology when you give curvature to a dam it becomes an arch dam as shown this arch dam deforms under the water loading now if you compare this dam’s deformed shape with its original shape you’ll notice that both the upstream and downstream fibers are undergoing a length reduction which means the whole damn body will be under compressive loading concrete can withstand strong compression forces this is the simple beauty of arch dam technology.

Lower the center of gravity the higher an object’s stability:

Points of paragraph:

  • A gravity arch dam
  • Tensile stress and stability
  • Resist sheer forces of water
  • Triangular in shape
A gravity arch dam
A gravity arch dam

 however if we put the dam under service it still has a good chance of toppling due to the water pressure we can solve this issue by increasing the dam’s width gradually toward the base the approach will lower the dam body’s center of gravity the lower the center of gravity the higher an object’s stability the design we achieved just now is called a gravity arch dam and this design can overcome the issues of tensile stress and stability this increasing width design can also resist sheer forces the water pressure diagram on the dam body is not uniform but is triangular in shape and increases toward the base however since the area of the dam increases toward the base the shear stress value at every cross section is nearly identical.

Big challenge for Mr. John savage is the Height of Hoover dam:

Advantages of Height increases and some problems:

  • Electricity generation.               
  • Flood control.
  • Maximum flood discharge ( P )
  • The dam’s lifespan    ( P )
  • River flow during rainfall.
  • More materials drastically increasing its construction cost.
ig challenge for Mr. John savage is the Height of Hoover dam:

the next big challenge savage faced was the height of the dam the higher the dam the greater its water storage capacity this is obviously an advantage for electricity generation and flood control but is it possible to construct a dam that is the same height as the mountain walls first we need to analyze the maximum flood discharge that can occur during the dam’s lifespan which depends on the regional rainfall data and catchment area after constructing such a tall dam even during a torrential river flow if the dam is not getting filled to its capacity then it has obviously been over designed moreover building a taller dam requires significantly more materials drastically increasing its construction cost therefore.

The height of effective in the water demand in cities and flood control:

  • The height was cost effective.
  •  The height he chose was 726 feet.
The height of effective in the water demand in cities and flood control:

 Mr. savage selected a height that was cost effective meets the water demand of nearby cities and also does flood control the height he chose was 726 feet the main design part of this dam is now complete now for the most interesting part executing its construction.

CONSTRUCTION DETAILS

  • Strong mountain walls
  • Weathered rock
  • Drilled holes using jackhammers
  • Blasted them using dynamite

 being an arch-gravity dam it needs strong mountain walls to transfer the load let’s take a cross-section of the mountains you can see the rocks on the surface are weathered and quite weak therefore the first task during the Hoover’s construction was to remove all those weathered rocks until only the virgin ones remained to reach the virgin rocks the workmen drilled holes using jackhammers.

Making deep holes the mountain wall

ep holes the mountain wall
ep holes the mountain wall

 and blasted them using dynamite after blasting acrobatic workmen were sent with ropes to clear loose rock from walls and the excavated material was transferred away via trucks this dam should have a strong joint with the sidewalls for this purpose they excavated the mountain wall in the shape of an arch again using dynamite explosion the dam body takes form from these deep holes making the mountain wall dam connection really strong.

Hard strata strong layer of soil

 The next big question is how the ground will bear the weight of such a massive dam when excavating it is crucial to reach a strong layer of soil called hard strata to find the hard strata the workers used power shovels and excavated the riverbed till a depth of a whopping 135 feet they excavated the riverbed in the same width as the base width of the dam.

  • Flow of river during construction:
  • Constructed temporary coffer dams.
  • diversion tunnels .

 one detail we didn’t mention yet is that before they began all this work they had to first divert the river flow in another direction to do so they constructed temporary coffer dams and diversion tunnels now it’s time for the concreting for this.

The formwork of Hoover dam:

  • Pouring the concrete.
  • Produces heat in concrete.
  • Material expansion and thermal cracks in the concrete.
The formwork of Hoover dam:
The formwork of Hoover dam:

 We must first arrange the formwork which is made up of wood for the concreting once the formwork or mold is done we’ll start pouring the concrete however the main issue here is that when cement reacts with water it produces heat considering the scale of the project pouring all the concrete at once will create an enormous store of heat which will result in material expansion and thermal cracks in the concrete making the project a failure.

The engineers divided the entire dam area into blocks system:

  • Each blocks approximately 50 by 50 feet.
  • Concrete blocks took much less time to cool.
  • Embedded two inch diameter steel pipes for cooling these blocks.

 Here is a construction innovation to solve this issue the engineers cleverly divided the entire dam area into a number of blocks each approximately 50 by 50 feet and poured concrete into each block mold work one by one these small quantities of concrete took much less time to cool in addition they embedded two inch diameter steel pipes into these blocks the pipes carried cool water which controlled the temperature in the concrete and set it quickly and easily once the concrete hardened workers filled these steel pipes with a grout cement slurry this technique proved so effective that the Hoover dam hasn’t shown any cracks to date now.

ELECTRICITY PRODUCTION:

  • Four huge towers inside the dam’s water.
  • These towers regulate water flow.
  • 500 foot long pen stocks.
Four huge towers inside the dam’s water.

 let’s explore the details of Hoover dam’s biggest application electricity production you might have observed four huge towers inside the dam’s water body these are intake towers several gates along the height of these towers regulate water flow rate the intake tower is then connected to these 500 foot long pen stocks that carry water to the turbines to generate power.

U-shaped power plant:

  • 17 Francis type vertical turbines.
  • Enough electricity to serve 100 000 people.
U-shaped power plant:

 Mr. savage designed a u-shaped power plant at the base of the dam downstream water from the pen stocks turns 17 Francis type vertical turbines which rotate a series of electric generators each of these generators produces enough electricity to serve 100 000 people later.

IRRIGATION PURPOSES

  • One million acres of land.
  • The largest man-made lake in the world.
  • Increasing the water level in land.
IRRIGATION PURPOSES

 This water is released through outlets downstream for irrigation purposes the Hoover dam irrigates more than one million acres of land interestingly the dam also creates one of the largest man-made lakes in the world Lake Mead this huge water storage facility helps groundwater recharge thus increasing the water level in nearby wells.

FLOOD CONTROL

  • When the dam is over flowed it can easily damage the system.
  • Spillways on either sides of dam.
  • These Spillways located 27 feet below top of the dam.
When the dam is over flowed it can easily damage the system.
When the dam is over flowed it can easily damage the system.

the next obvious application of Hoover dam is flood control in case of flood or heavy rains the dam stores the water in the reservoir and prevents its flow from threatening the lives and structures in the downstream area now let’s consider a small design challenge what if the dam overflows it can easily damage the structures constructed downstream to solve this potential problem they constructed passageways called spillways on either side of the dam upstream so that water can be spilled downstream these spills are located 27 feet below the top of the dam if water reaches that level it starts flowing into spillways.

WATER SEEPAGE:

  • Liquid under pressure
  • Tunnel that collects all seepage water from the dam body.

did you know that you can actually walk inside the Hoover dam body several tunnels are hidden inside the dam body they have to construct these tunnels because of a simple phenomenon with which we’re all familiar water seepage a liquid under pressure always wants to escape through porous material.

SEEPAGE EFFECT:

  • Generates a high uplift pressure.
  • Drastically reducing its stability of dam.
  • Tunnel that collects all seepage water.
  • The Hoover dam is still standing strong and serving the nation.
WATER SEEPAGE:
WATER SEEPAGE:

 Here the water molecules flow through the soil below the dam body due to the seepage effect the issue is that this flow generates a high uplift pressure on the base of the dam drastically reducing its stability this is why Mr. savage designed a gallery a tunnel that collects all seepage water from the dam body and base this action reduces the uplift pressure considerably the collected water is then discharged safely the galleries also provide passageways for leak or crack inspections such detailed engineering plants with a future focused vision are the reason why the Hoover dam is still standing strong and serving the nation.

  • Lessen would like to pay homage to all 96 workers who sacrificed their lives to make this gigantic dam.

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