The Colorado river was a line of failures of political forces near the 1920’s, as the seven states of its basin continued to grow in the population. A compact compact of 1922 allocated river water rights, but farmers in the Imperial Valley of California suffered unpredictable flows and requested a dam that provided flood control and a constant supply of irrigation water. Los Angeles officials sought additional water for their expanding city, while politicians and business interests had the potential for energy generation. All this marked the stage for Congress, passing a plan in 1928 to take the river.
This is the highest prey in the world at 729 feet, surpassing the then 417 foot Record Dam in Oregon, Hoover’s Dam was an unprecedented project, with the Claim Office that conducted research on physics, mechanics, elasticity, hydraulics, chemistry, seisism and structural geology.
He developed “new mathematical equations, new stress analysis methods, new methods of model test test, new specifications for cement and new determinations for concrete thermal properties”, according to a 1932 article by Elwood Mead, the office curator.
Enlightened Illustration of Archives
Once it was decided that an arc-gravity dam be built, an accuracy of the test load analysis method should be established. Thus, “ it was necessary to accurately determine the effects of the tangential shear, the rotation, the relation of Poisson, the flow, the variations of the internal temperature, the sides of radial cantilever, the deformations of foundation and the buttress, the shocks of the earthquake, the propagation of walls of the barrel due to the pressure of the water of the tank, the pressure of the porus of the conconimon ”.
The office received three offers and awarded the contract to Six Companies Inc., a joint company in 1931. The chosen site, Black Canyon, was 30 kilometers from Las Vegas, 9,000 inhabitants. It was the height of the Great Depression, and more than 10,000 unemployed people converged on Las Vegas in the hope of hiring -even before the contract was granted. A campfire camp near the prey was soon surrounded by a Escatters camp known as McKeversville. Another camp near the river was known as Ragetown. Fifty-nine miles of railway were established, with an intense classification, five tunnels and a wooden disorder across the river. A 225 mile transmission line was erected to provide energy to the site. A planned city of modest houses was built for 5,000 workers, called Boulder City. Alcohol and gambling was banned and workers had to enter through a gateway.
COVER OF THE FILE ENR
A 150 -ton capacity cable was installed and it was used to transport 46,000 tonnes of pipe sections to four platforms of the cannon, as well as doors, valves, center gears, machinery and even trucks. The cement came from four floors in California, delivered by rail and mixed to the site. An aggregate plant in the site produced 500 tonnes per hour.
The first important task was the excavation of four massive deviation tunnels, each of 4,000 feet long and 56 feet a day. The ads were led to the barrel walls at the mid -tunnel points, providing, with portals, four attack points in each tunnel. The workers used pneumatic diamond tip exercises for holes in the nucleus, which were filled with dynamite and explosed. Mobile perforation platforms, which consist of three -level platforms mounted on flat trucks, let a dozen or more perforators drill simultaneously on the tunnel faces, while 100 tonnes electric blades eliminated the rubble.
When rock conditions were ideal and no supports were needed, the tunnels were covered with 3 feet of concrete for durability and smooth water flow. The continuous convoys of trucks handed over 2 batch concrete buckets. Rolled lifts were used to place the concrete for inverted and sides. A coiled platform called the side wall jumbo – a huge shape of metal metal with dozens of metal chutes – a concrete that decreased for the tunnel walls. The men continued behind the way to work the concrete against the rock. The concrete for the sections of the upper tunnel arch was piled through hoses in tire concrete cannons. Finally, Group was injected into the surrounding rock.
The drainage process began after the riverbed in the tunnels in November 1932. The rubble rushed to the river and water was pumped, exposing the riverbed. Cofferdams were built up and downstream of the dam. The largest upstream was impressive in itself, 98 feet high, containing 568,000 c. The excavated filling and gravel filling were transported to both cofferdams by rail. Cofferdams were completed in the spring of 1933, in advance of the flood season.
Perhaps the most spectacular workers were the “high stairs”: a hundred men, suspended by ropes, the non -loose rock of the barrel walls with pneumatic jackhammers, followed by perforation and explosion. This was done for the places of the four water entry towers, the downstream, as well as the main buttresses of the dam. The abutment excavation took a year and was completed in mid -1933. The river excavation meant the elimination of the ardes, sand and rock over 100 feet down before hitting the bed.
The designer of the dam was John L. Savage, chief design engineer of the Claim Office. He oversaw the design of 60 major prey and consulted hundreds of other countries.
The shape of the dam wedge consists of hundreds of concrete columns intertwined, which vary from 55 feet x 60 feet on the face up to 25 feet x 30 feet on the face downstream. Fallen edges like the block of the blocks help them to nest and resist the movement under pressure. As the casting progressed, the blocks increased on average 30 feet a month. The circumference and radial joints helped the blocks to resist and distribute pressure from the side. The concrete was supplied in 20-tonous buckets, 8-cu-yd by cable and was thrown into 5-foot elevators for each block. It took up to 100 buckets to fill each lift.
The main technical challenge was to dissipate the tremendous heat emitted by the concrete as it was cured, which if it did not go a few cracked. A 300 -mile day pipe system were installed. A retention with perforated pipes was placed on all vertical and horizontal joints, and a three rows curtain was installed throughout the buttress, from the edge to the barrel. The concrete placement began in June 1933 and was constantly, with an average of 6,000 Cu per day, with a rejunta completed in June 1935.
The dam has networks of internal galleries for inspection, drainage of water and rejunt. With a maximum width of 660 feet at the base, tilting 45 feet on the 1,180 feet ridge of Longi
The four entrances to the dam are the reinforced concrete towers of 380 feet high that houses axes of 32 feet of day that feed on two of the deviation tunnels. They adjust the flow to supply generators downstream to a constant and precalculated water pressure. Design calculations requested that the entrance pipes be 30 feet a day, so 30 -foot steel pledges were installed inside the deviation tunnels. Babcock & Wilcox Co., the Penstock sections were made at the site and transported to the deviation tunnels through the ads on the barrel walls. Two types of valves maintain the pressure and flow of water through the sorrows and generators. 14 -foot butterfly valves in day control water that goes to the turbines. Two sets of six giant needle valves in each valve house could leave up to 15,500 gallons per second, shooting 450 feet to hit the opposite walls. Two slopes, one on both sides of the dam, have 650 feet -long basins and were equipped with four drum doors of 100 feet X 16 feet. They feed on the diversion tunnels and each can pass 200,000 feet of water per second, double the maximum flow of the Niagara falls.
The work was completed two years before the calendar of 1936. A total of 21,000 workers were used during the five years of construction, with 112 deaths, including 16 who succumbed to the exhaustion of the heat during a strong heat wave of 1931, where the temperatures reached 119.9 ° F. When the ninth of a possible 17 generators settled in 1939, the prey was the greatest capacity of the central hydroelectric capacity. world. The sale of electricity generated by the dam paid for its cost of construction in 1987.
