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Internal Erosion
Internal erosion is the formation of voids within a soil caused by the removal of material by seepage. It is the second most common cause of failure in levees and one of the leading causes of failures in earth dams, responsible for about half of embankment dam failures. Internal erosion occurs when the hydraulic forces exerted by water seeping through the pores and cracks of the material in the dam and/or foundation are sufficient to detach particles and transport them out of the dam structure. Internal erosion is especially dangerous because there may be no external evidence, or only subtle evidence, that it is taking place. Usually a sand boil can be found, but the boil might be hidden under water. A dam may breach within a few hours after evidence of internal erosion becomes obvious. Piping is a related phenomenon and is defined as the progressive development of internal erosion by seepage, appearing downstream as a hole discharging water. Piping is induced by regressive ero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seepage
In soil mechanics, seepage is the movement of water through soil. If fluid pressures in a soil deposit are uniformly increasing with depth according to u = \rho_w g z_w, where z_w is the depth below the water table, then hydrostatic conditions will prevail and the fluids will be flowing through the soil. However, if the water table is sloping or there is a perched water table as indicated in the accompanying sketch, then seepage will occur. For steady state seepage, the seepage velocities are not varying with time. If the water tables are changing levels with time, or if the soil is in the process of consolidation, then steady state conditions do not apply. Darcy's law Darcy's law states that the volume of flow of the pore fluid through a porous medium per unit time is proportional to the rate of change of excess fluid pressure with distance. The constant of proportionality includes the viscosity of the fluid and the intrinsic permeability of the soil. For the simple case of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shear Stress
Shear stress (often denoted by , Greek alphabet, Greek: tau) is the component of stress (physics), stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress or force per unit area is: \tau = ,where is the force applied and is the cross-sectional area. The area involved corresponds to the material face (geometry), face parallel to the applied force vector, i.e., with surface normal vector perpendicular to the force. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as:\tau_w := \mu\left.\frac\_,where is the dynamic viscosity, is the flow velocity, and is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cementation (geology)
Minerals bond grains of sediment together by growing around them. This process is called cementation and is a part of the rock cycle. Cementation involves ions carried in groundwater chemically precipitating to form new crystalline material between sedimentary grains. The new pore-filling minerals form "bridges" between original sediment grains, thereby binding them together. In this way, ''sand'' becomes sandstone, and ''gravel'' becomes conglomerate or breccia. Cementation occurs as part of the diagenesis or lithification of sediments. Cementation occurs primarily below the water table regardless of sedimentary grain sizes present. Large volumes of pore water must pass through sediment pores for new mineral cements to crystallize and so millions of years are generally required to complete the cementation process. Common mineral cements include calcite, quartz, and silica phases like cristobalite, iron oxides, and clay minerals; other mineral cements also occur. Cement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granular Filter
Granularity (also called graininess) is the degree to which a material or system is composed of distinguishable pieces, "granules" or "grains" (metaphorically). It can either refer to the extent to which a larger entity is subdivided, or the extent to which groups of smaller indistinguishable entities have joined together to become larger distinguishable entities. Precision and ambiguity Coarse-grained materials or systems have fewer, larger discrete components than fine-grained materials or systems. * A coarse-grained description of a system regards large subcomponents. * A fine-grained description regards smaller components of which the larger ones are composed. The concepts granularity, coarseness, and fineness are relative; and are used when comparing systems or descriptions of systems. An example of increasingly fine granularity: a list of nations in the United Nations, a list of all states/provinces in those nations, a list of all cities in those states, etc. Physics A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Particle Segregation
In particle segregation, particulate solids, and also quasi-solids such as foams, tend to segregate by virtue of differences in the size, and also physical properties such as volume, density, shape and other properties of particles of which they are composed. Segregation occurs mainly during the powder handling and it is pronounced in free-flowing powders. One of the effective methods to control granular segregation is to make mixture's constituents sticky using a coating agent. This is especially useful when a highly active ingredient, like an enzyme, is present in the mixture. Powders that are inherently not free flowing and exhibit high levels of cohesion/adhesion between the compositions are sometimes difficult to mix as they tend to form agglomerates. The clumps of particles can be broken down in such cases by the use of mixtures that generate high shear force In solid mechanics, shearing forces are unaligned forces acting on one part of a Rigid body, body in a specifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Gradation
In soil science, soil gradation is a classification of a coarse-grained soil that ranks the soil based on the different particle sizes contained in the soil.Holtz, R. and Kovacs, W. (1981), ''An Introduction to Geotechnical Engineering'', Prentice-Hall, Inc. Soil gradation is an important aspect of soil mechanics and geotechnical engineering because it is an indicator of other engineering properties such as compressibility, shear strength, and hydraulic conductivity. In a design, the gradation of the ''in situ'' (on site) soil often controls the design and ground water drainage of the site. A poorly graded soil will have better drainage than a well graded soil, 4 & 1 < Cc < 3 If both of these criteria are not met, the gravel is classified as poorly graded or GP. If both of these criteria are met, the gravel is classified as well graded or GW. For a sand to be classified as well graded, the following criteria must be met: Cu ≥ 6 & 1 < Cc < 3 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surrey
Surrey () is a Ceremonial counties of England, ceremonial county in South East England. It is bordered by Greater London to the northeast, Kent to the east, East Sussex, East and West Sussex to the south, and Hampshire and Berkshire to the west. The largest settlement is Woking. The county has an area of and a population of 1,214,540. Much of the north of the county forms part of the Greater London Built-up Area, which includes the Suburb, suburbs within the M25 motorway as well as Woking (103,900), Guildford (77,057), and Leatherhead (32,522). The west of the county contains part of Farnborough/Aldershot built-up area, built-up area which includes Camberley, Farnham, and Frimley and which extends into Hampshire and Berkshire. The south of the county is rural, and its largest settlements are Horley (22,693) and Godalming (22,689). For Local government in England, local government purposes Surrey is a non-metropolitan county with eleven districts. The county historically includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delft
Delft () is a List of cities in the Netherlands by province, city and Municipalities of the Netherlands, municipality in the Provinces of the Netherlands, province of South Holland, Netherlands. It is located between Rotterdam, to the southeast, and The Hague, to the northwest. Together with them, it is a part of both the Rotterdam–The Hague metropolitan area and the Randstad. Delft is a popular tourist destination in the Netherlands, famous for its historical connections with the reigning House of Orange-Nassau, for its Delftware, blue pottery, for being home to the painter Johannes Vermeer, Jan Vermeer, and for hosting Delft University of Technology (TU Delft). Historically, Delft played a highly influential role in the Dutch Golden Age. In terms of science and technology, thanks to the pioneering contributions of Antonie van Leeuwenhoek and Martinus Beijerinck, Delft can be considered to be the birthplace of microbiology. History Early history The city of Delft came int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delft University Of Technology
The Delft University of Technology (TU Delft; ) is the oldest and largest Dutch public university, public Institute of technology, technical university, located in Delft, Netherlands. It specializes in engineering, technology, computing, design, and natural sciences. It is considered one of the leading technical universities in Europe and is consistently ranked as one of the best schools for architecture and engineering in the world. According to the QS World University Rankings it ranked 3rd worldwide for architecture and 13th for Engineering, Engineering & Technology in 2024. It also ranked 3rd best worldwide for Mechanical engineering, mechanical and aerospace engineering, 3rd for Civil engineering, civil and structural engineering, 11th for chemical engineering, and 12th for design. With eight Faculty (division), faculties and multiple research institutes, TU Delft educates around 27,000 students (undergraduate and postgraduate), and employs more than 3,500 doctoral candidates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand. One such example of this is aragonite, which has been created over the past 500million years by various forms of life, such as coral and shellfish. It is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years, as in the Caribbean. Somewhat more rarely, sand may be composed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hanging Valley - Geograph
Hanging is killing a person by suspending them from the neck with a noose or ligature strangulation, ligature. Hanging has been a standard method of capital punishment since the Middle Ages, and has been the primary execution method in numerous countries and regions. The first known account of execution by hanging is in Homer's ''Odyssey''. Hanging is also a Suicide by hanging, method of suicide. Methods of judicial hanging There are numerous methods of hanging in execution that instigate death either by cervical fracture or by Strangling, strangulation. Short drop The short drop is a method of hanging in which the condemned prisoner stands on a raised support, such as a stool, ladder, cart, horse, or other vehicle, with the noose around the neck. The support is then moved away, leaving the person dangling from the rope. Suspended by the neck, the weight of the body tightens the noose around the neck, effecting strangulation and death. Loss of consciousness is typically rapid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jet Erosion Test
The jet erosion test (JET), or jet index test, is a method used in geotechnical engineering to quantify the resistance of a soil to erosion. The test can be applied in-situ after preparing a field site, or it can be applied in a laboratory on either an intact or a remolded soil sample. A quantitative measure of erodibility allows for the prediction of erosion, assisting with the design of structures such as vegetated channels, road embankments, dams, levees, and spillways.ASTM D5852-00. Procedure The test consists of mounting a jet tube inside of an enclosed cylinder and releasing a turbulent downpour of water onto a soil specimen at a constant hydraulic head. If the shear stress applied by the jet stream exceeds the critical shear stress for erosion of the soil, the jet will erode soil particles, causing a scour Scour may refer to: Hydrodynamic processes * Hydrodynamic scour, the removal of sediment such as sand and silt from around an object by water flow ** Bridge s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
