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Pore Fluid Pressure
Pore water pressure (sometimes abbreviated to pwp) refers to the pressure of groundwater held within a soil or rock, in gaps between particles ( pores). Pore water pressures below the phreatic level of the groundwater are measured with piezometers. The vertical pore water pressure distribution in aquifers can generally be assumed to be close to hydrostatic. In the unsaturated ("vadose") zone, the pore pressure is determined by capillarity and is also referred to as tension, suction, or matric pressure. Pore water pressures under unsaturated conditions are measured with tensiometers, which operate by allowing the pore water to come into equilibrium with a reference pressure indicator through a permeable ceramic cup placed in contact with the soil. Pore water pressure is vital in calculating the stress state in the ground soil mechanics, from Terzaghi's expression for the effective stress of the soil. General principles Pressure develops due to: *''Water elevation differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the "gauge" spelling. is the pressure relative to the ambient pressure. Various #Units, units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the International System of Units, SI unit of pressure, the Pascal (unit), pascal (Pa), for example, is one newton (unit), newton per square metre (N/m2); similarly, the Pound (force), pound-force per square inch (Pound per square inch, psi, symbol lbf/in2) is the traditional unit of pressure in the imperial units, imperial and United States customary units, US customary systems. Pressure ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effective Stress
Effective stress is a fundamental concept in soil mechanics and geotechnical engineering that describes the portion of total stress in a soil mass that is carried by the solid soil skeleton, rather than the pore water. It is crucial for understanding the mechanical behaviour of soils, as effective stress governs both the strength and volume change (deformation) of soil. More formally, effective stress is defined as the stress that, for any given pore pressure p, produces the same strain or strength response in a porous material (such as soil or rock) as would be observed in a dry sample where p = 0. In other words, it is the stress that controls the mechanical behaviour of a porous body regardless of pore pressure present. This concept applies broadly to granular media like sand, silt, and clay, as well as to porous materials such as rock, concrete, metal powders and biological tissues. History Karl von Terzaghi first proposed the relationship for effective stress in 1925. For ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension (chemistry), suspension with water. Silt usually has a floury feel when dry, and lacks Plasticity (physics), plasticity when wet. Silt can also be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles). Silt is a common material, making up 45% of average modern mud. It is found in many river deltas and as wind-deposited accumulations, particularly in central Asia, north China, and North America. It is produced in both very hot climates (through such processes as collisions of quartz grains in dust storms) and very cold climates (through such processes as glacial grinding of quartz grains.) Loess is soil rich in silt which makes up some of the most fertile agricultural land on Earth. However, silt is very vulnerable to erosion, and it has poo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clay
Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite, ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide. Clays develop plasticity (physics), plasticity when wet but can be hardened through Pottery#Firing, firing. Clay is the longest-known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery. Some of the earliest pottery shards have been radiocarbon dating, dated to around 14,000 BCE, and Clay tablet, clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtration, filtering. Between one-half and two-thirds of the world's population live or work in buildings made with clay, often baked into brick, as an essenti ... [...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] |
Terzaghi's Principle
Terzaghi's Principle states that when stress is applied to a porous material, it is opposed by the fluid pressure filling the pores in the material. Karl von Terzaghi introduced the idea in a series of papers in the 1920s based on his examination of building Soil consolidation, consolidation on soil. The principle states that all quantifiable changes in Stress (physics), stress to a porous medium are a direct result of a change in effective stress. The ''effective stress,'' \boldsymbol_, is related to ''total stress,'' \boldsymbol , and the ''pore pressure,'' P, by :\boldsymbol_ = \boldsymbol - P\mathbb , where \mathbb I is the Identity Matrix, identity matrix. The negative sign is there because the pore pressure serves to lessen the volume-changing stress; physically this is because there is fluid in the pores which bears a part of the total stress, so partially unloading the solid matrix from normal stresses. Terzaghi's principle applies well to porous materials whose solid con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tensiometer
Tensiometer may refer to one of a number of devices. The two most common are: * Tensiometer (surface tension) an instrument used to measure the surface tension of liquids * Tensiometer (soil science) an instrument to determine matric water potential {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ASTM International
ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and services. Some 12,575 apply globally. The headquarters is in West Conshohocken, Pennsylvania, about northwest of Philadelphia. It was founded in 1902 as the American Section of the International Association for Testing Materials. In addition to its traditional standards work, ASTM operates several global initiatives advancing additive manufacturing, advanced manufacturing, and emerging technologies, including the Additive Manufacturing Center of Excellence (AM CoE), the acquisition oWohlers Associatesfor market intelligence and advisory services, and the National Institute of Standards and Technology, NIST-funded Standardization Center of Excellence (SCOE). History In 1898, a group of scientists and engineers, led by chemist, industry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Bureau Of Reclamation
The Bureau of Reclamation, formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and operation of the diversion, delivery, and storage projects that it has built throughout the western United States for irrigation, water supply, and attendant hydroelectric power generation. It is currently the U.S.'s largest wholesaler of water, bringing water to more than 31 million people, and providing one in five Western farmers with irrigation water for 10 million acres of farmland, which produce 60% of the nation's vegetables and 25% of its fruits and nuts. The Bureau is also the second largest producer of hydroelectric power in the western U.S. On June 17, 1902, in accordance with the Reclamation Act, Secretary of the Interior Ethan Allen Hitchcock established the U.S. Reclamation Service within the U.S. Geological Survey (USGS). The n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transducer
A transducer is a device that Energy transformation, converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, Measuring instrument, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.). The process of converting one form of energy to another is known as transduction. Types * Mechanical transducers convert physical quantities into mechanical outputs or vice versa; * Electrical transducers convert physical quantities into electrical outputs or signals. Examples of these are: ** a thermocouple that changes temperature differences into a small voltage; ** a linear variable differential transformer (LVDT), used to measure displacement (position) changes by means of electrical signals. Sensors, actuators and transceivers Transducers can be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piezometric Head
Hydraulic head or piezometric head is a measurement related to Fluid pressure#Hydrostatic pressure, liquid pressure (normalized by specific weight) and the liquid elevation above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22, eq.3.2a. It is usually measured as an equivalent liquid surface elevation, expressed in units of length, at the entrance (or bottom) of a piezometer. In an aquifer, it can be calculated from the depth to water in a piezometric well (a specialized water well), and given information of the piezometer's elevation and screen depth. Hydraulic head can similarly be measured in a column of water using a standpipe piezometer by measuring the height of the water surface in the tube relative to a common datum. The hydraulic head can be used to determine a ''hydraulic gradient'' between two or more points. Definition In fluid dynamics, the ''head'' at some point in an Incompressible flow, incompressible (constant density) flow is equal to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity
In physics, gravity (), also known as gravitation or a gravitational interaction, is a fundamental interaction, a mutual attraction between all massive particles. On Earth, gravity takes a slightly different meaning: the observed force between objects and the Earth. This force is dominated by the combined gravitational interactions of particles but also includes effect of the Earth's rotation. Gravity gives weight to physical objects and is essential to understanding the mechanisms responsible for surface water waves and lunar tides. Gravity also has many important biological functions, helping to guide the growth of plants through the process of gravitropism and influencing the circulation of fluids in multicellular organisms. The gravitational attraction between primordial hydrogen and clumps of dark matter in the early universe caused the hydrogen gas to coalesce, eventually condensing and fusing to form stars. At larger scales this results in galaxies and clust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
