IF the downstream toe of dam gets saturated by piping or any seepage action, it will get eroded and forms small slide or small slump. The slump will create steeper face which again gets eroded due to seepage and form slump again. This progressive removal of saturated soil is called sloughing.
What is sloughing in excavation?
Soil sloughing is soil falling off banks and slopes due to a loss in cohesion. Soil sloughs off for the same reasons as landslides in general, with very wet soil being among the leading factors. Sloughing is a relatively shallow phenomenon involving the uppermost layers of the soil.
What is piping and how will you control piping in case of earthen dam?
Seepage flow which is muddy and carrying sediment (soil particles) is evidence of “piping,” and is a serious condition that if left untreated can cause failure of the dam. Piping can most often occur along a spillway or other conduit through the embankment, and these areas should be closely inspected.
What is piping failure in dam?
Internal erosion (called “piping” by dam engineers) of an earth dam takes place when water that seeps through the dam carries soil particles away from the embankment, filters, drains, foundation or abutments of the dam.
What is sloughing in biology?
Sloughing, in biology, shedding or casting off dead tissue. Skin sloughing, shedding dead surface cells off the skin.
What are the 3 types of excavation?
10 Types of Excavation
- Bridge Excavation. Whether you’re building arch, beam or suspension bridges, you need a strong foundation to build on.
- Borrow Excavation.
- Channel Excavation.
- Drainage Excavation.
- Dredge Excavation.
- Stripping.
- Earth Excavation.
- Muck Excavation.
How can we prevent earthen dam sloughing?
(a) Quantity of seepage water through the dam section and foundation should be limited. (b) The seepage line should be well within the downstream face of the dam to prevent sloughing.
What is seepage loss?
1 Estimation of Seepage Loss. Seepage may be defined as the infiltration downward and lateral movement of water into soil or substrata from a source of supply such as reservoir or irrigation canal. Such water may reappear, depending upon the topographic contours and water table rise due to seepage.
What is exit gradient in dam?
For the soil grain to remain stable, the submerged weight of soil grain should be more than this upward force. This force at any point is proportional to the gradient of the pressure of water at that point. This gradient of the pressure of water at the exit end is called the exit gradient.
What are the types of piping?
Most Common Types Of Plumbing Pipes. There are five plumbing pipe materials that are — or were in the case of galvanized steel — most common: copper, galvanized steel, polyvinyl chloride (PVC), chlorinated polyvinyl chloride (CPVC) and cross-linked polyethylene (PEX).
What causes piping failure?
The common causes of pipe failure are corrosion, water velocity, clogging, movement, and extreme temperatures. To prolong its use, ensure that the appropriate class, grade, and material are used before installation. Also, consider the environmental elements present on the site to prevent problems in the future.
What is piping and exit gradient?
Hydraulic structure becomes unstable and may fail. This type of Piping is called backward erosion piping. Generally, backward erosion piping failure occurs when the exit gradient becomes greater than the critical hydraulic gradient. The hydraulic gradient near the exit point of the water is called the exit gradient.
What is overturning failure in dam?
If the resultant of all the forces acting on a dam at any of its sections, passes through toe, the dam will rotate and overturn about the toe. This is called overturning failure of gravity dam.
How does a slough form?
Formation. A slough can form when a meander gets cut off from the main river channel creating an oxbow lake that accumulates with fine overbank sediment and organic material such as peat. This creates a wetland or swamp environment.
What is a synonym for slough?
Some common synonyms of slough are cast, discard, junk, scrap, and shed.
What is the 5 foot rule excavation?
Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required.
What are the two methods of digging?
Digging may be simple digging, double digging or deep trenching.
What are the types of shoring?
Here are several different shoring types that construction professionals use:
- H and I-beam shoring.
- Secant pile shoring.
- Contiguous pile shoring.
- Sheet piles.
- Diaphragm walls.
- Raking shoring.
- Hydraulic shoring.
- Soil nail shoring.
How do you stop a leaking dam?
There are seven main solutions that are most often employed to fix leaking dams:
- compacted earth clay lining.
- bentonite dry blanket.
- bentonite wet blanket.
- concrete linings.
- bituminous sprays or coatings.
- pre-fabricated lining membranes.
- polymer plugs.
What is seepage control?
Groundwater control (also known as seepage control) involves the creation of barriers in soil, rock, or below-grade structures to restrict the movement of water.
What is rip rap in dam construction?
Rock riprap consists of a heterogeneous mixture of irregular shaped rocks placed over gravel bedding and a sand filter or geotextile fabric. The smaller rocks help to fill the spaces between the larger pieces forming an interlocking mass.