Earth Embankment Dam Filters
Introduction
The embankment dam is a massive man-made water barrier. It is created for the purpose of compaction and emplacement of semi plastic mounds having the composition of various components such as soil, clay and rock etc. Nature provides a pseudo permanent waterproof covering for the surface and waterproof core of such dams. The principle of working of such dams is, the force of impoundment creates a downward thrust upon the mass of dam which increase the weight of dam on its foundation. This added force effectively seals and makes waterproof the underlying foundation of the dam, at the interface between dam and stream bed.
The earth embankment dam use filters. Filters in embankment dams are constructed specifically using designed entities (zones) of coarser grained soils placed at specific locations within or adjacent to the dam structure. Filters are designed and constructed to meet specific goals like preventing internal soil movement and controlling drainage, and are typically implemented during new dam construction. Filters have also been added to improve the performance of existing dams to meet specific requirements.
Purpose and functions of filters
Filters are the means of controlling and directing the flow of seepage water through dams for hundreds of years. Filters are used to prevent movement of soil particles from or between various zones and foundations of embankment dams. Such movement, if not controlled, can result in the development of concentrated leaks that can lead to serious consequences and, in extreme cases, failure of an embankment dam. In fact, approximately 50% of all dam failures are attributed to excess seepage. These sort of failures are progressive in nature and begi...
... middle of paper ...
...itical zones in the embankment and the foundation. Economical design requires the use of materials that protect against failure yet are easily constructed. Since filter materials are some of the costliest materials used in a dam, effort is placed in minimizing the amount of material used. Therefore, the balance of cost, constructability, and reliability go hand-in-hand in providing an economically safe structure.
The main function of filters is to prevent movement of soil particles due to water flow within and beneath embankment dams or other water retaining structures. Soil particle movement can occur through two basic mechanisms: backward erosion piping and internal erosion. Filters provide protection against these two anomalies progressing toward development of a concentrated leak that could cause excessive loss of water or eventual failure of the structure.
The Oroville dam is a rock fill embankment dam, which means, a water barrier that is made with certain materials so that it isn’t prone to erosion or deterioration. Because the material is so heavy due to the need for a secure dam, , it creates a much stronger barrier and base to its foundation. A study was done to see if a rock fill dam is the most stable type of dam to hold the amount of water it is expected to. The study tested different types of dams stability compared to the stability of a rock fill, and ultimately found that the rock fill is completely acceptable and safe (Lei). The Feather River is the only river to feed into the dam, filling it to its total capacity of 3,507,977 acre/ft.
Dams made from dirt are very weak and the South Fork dam was built entirely with dirt. From an engineering standpoint dams made with dirt needed to be built ...
Darcy’s law provides an accurate description of the flow of ground water in almost all hydrogeological environments. Henri Darcy established empirically that the flux of water through a permeable formation is proportional to the distance between top and bottom of the soil column.
Flood control is the main reason for building the Three Gorges Dam. Since Han Dynasty (300BC), flood has been killed millions of lives, and destroyed millions of acres of farmland and homes every ten years. Billions of money has been spent on recovering the damage. The Three Gorges Dam is meant to be responsible for controlling the flood by changing the water height of the reservoir upstream from the dam according to season. It was planned to allow the water level to reach 185 meters above the sea level during the dry season, from November to April, and reduce to 135 meters during flooding months in order to attempt to contain flood waters. ("Biggest flood control,")
Since the 1920's, when the dam was first proposed, the Three Gorges Dam has been a topic for debate in the People's Republic of China. The construction of the world's largest hydro-electric project on the Yangtze River would be a detriment to the native flora and fauna, submerge rich farmlands, destroy archaeological sites, and force the evacuation of millions of people. Faced with international, as well as domestic, criticism about the ecological and social havoc the Three Gorges Dam would cause, the government of China has remained unnerved and has started construction on this highly questionable project. In December of 1995, Chinese Premier Li Peng officially launched the project at a construction site at Sandouping. However, the fight is not over yet since it will take close to twenty years to finish this massive water project.
According to Dams as Aid author Ann Usher (1997), “a man-made dam is a cement wall that blocks the natural flow of a river” (p. 3).
Dams operate by using water as its main source of power. They produce power from fast volumes of moving water that turns a generator. This falling water at one gallon of water per second, can create one kilowatt of electrical power if it falls one hundred feed. When water behind a dam is released, it runs through a pipe called a penstock, which then delivers it to the turbine. Different shapes are used on these turbines, but are generally created to harness kinetic force of the moving water as well as the water pressure.
The dam could not be poured in a single pour due to its size, so the engineers had to think of a different method. They decided to pour the concrete in five foot high forms of varying widths, which were stacked together. Each form had multiple 1 inch steel pipes in it, totaling to 582 miles of pipe. These pipes had cool water pumped through them to speed up the curing process. The base of the dam alone needed 230 individual blocks of concrete. The blocks were stacked with alternating schemes to add to the strength. Once the block of concrete was poured and cured, the pipes were filled with grout to add extra support. Grout was also poured in between the blocks of concrete.
contaminate the groundwater when fertilizers, pesticides, and septic tanks leak. If they are not installed properly and leak, the bacteria and the human waste goes into the groundwater and contaminates it.
IYER, R.I. (19X9) "Large Dams: The Right Perspective.' Economic and Political Weekly, 14, 107- 116.
Rubber Dam, hydraulic structure made of rubber fabric used for controlling the stream at different heights of flow is a stimulating concept for research as mo...
Moreover, the irrigation systems are designed considering steady and uniform flow however, these can barely find in irrigation systems nowadays. The irrigation systems have become more demand driven with frequent change in flow requiring frequent operation of flow control structures. This canal operation leads to unsteady and non-uniform flow which opposes the assumptions made thus these schemes require high maintenance cost because of the unwanted erosion or sedimentation in the
These facilities are: impounded, diversion, and pumped storage. Some of these facilities use dams and some don’t.
Basically, after a screen filter had removed the larger debris, media filter such as rapid sand filter will be further filtering out organic material like algae and bacterial slimes as well as fine sediments such as silt and clay (Bartok, 2009). However, this treatment requires a large area. It may be different from the other media filter which is slow sand filter. (Figure 1.5) As the slow sand filtration used much finer sand compared to the rapid sand filter where the sand used is larger than 1 mm in
“Water purification is removing undesired chemicals, biological contaminants, suspended solids and gases from contaminated water” (www.science.howstuffworks.com). The first experiments for water purification and filtration were in the seventeenth century. Sir Francis Bacon attempted to remove salts from seawater by passing through a filter made up of sand, charcoal, and rocks (www.science.howstuffworks.com). Water filtration has grown and become more advanced in technology over the past centuries (www.a...