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  2. Rankine theory - Wikipedia

    en.wikipedia.org/wiki/Rankine_theory

    Rankine's theory (maximum-normal stress theory), developed in 1857 by William John Macquorn Rankine, [1] is a stress field solution that predicts active and passive earth pressure. It assumes that the soil is cohesionless, the wall is frictionless, the soil-wall interface is vertical, the failure surface on which the soil moves is planar , and ...

  3. Lateral earth pressure - Wikipedia

    en.wikipedia.org/wiki/Lateral_earth_pressure

    The coefficient of lateral earth pressure, K, is defined as the ratio of the horizontal effective stress, σ’ h, to the vertical effective stress, σ’ v.The effective stress is the intergranular stress calculated by subtracting the pore water pressure from the total stress as described in soil mechanics.

  4. Pressure coefficient - Wikipedia

    en.wikipedia.org/wiki/Pressure_coefficient

    All the three aerodynamic coefficients are integrals of the pressure coefficient curve along the chord. The coefficient of lift for a two-dimensional airfoil section with strictly horizontal surfaces can be calculated from the coefficient of pressure distribution by integration, or calculating the area between the lines on the distribution.

  5. Thermodynamic activity - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_activity

    The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.

  6. Water activity - Wikipedia

    en.wikipedia.org/wiki/Water_activity

    The definition of a w is where p is the partial water vapor pressure in equilibrium with the solution, and p* is the (partial) vapor pressure of pure water at the same temperature. An alternate definition can be a w ≡ l w x w {\displaystyle a_{w}\equiv l_{w}x_{w}} where l w is the activity coefficient of water and x w is the mole fraction of ...

  7. Soil mechanics - Wikipedia

    en.wikipedia.org/wiki/Soil_mechanics

    A lateral earth stress coefficient, K, is defined as the ratio of lateral (horizontal) effective stress to vertical effective stress for cohesionless soils (K=σ' h /σ' v). There are three coefficients: at-rest, active, and passive. At-rest stress is the lateral stress in the ground before any disturbance takes place.

  8. Pore water pressure - Wikipedia

    en.wikipedia.org/wiki/Pore_water_pressure

    An ISO standard, "Soil quality — Determination of pore water pressure — Tensiometer method", ISO 11276:1995, "describes methods for the determination of pore water pressure (point measurements) in unsaturated and saturated soil using tensiometers. Applicable for in situ measurements in the field and, e. g. soil cores, used in experimental ...

  9. Specific storage - Wikipedia

    en.wikipedia.org/wiki/Specific_storage

    The specific storage is the amount of water that a portion of an aquifer releases from storage, per unit mass or volume of the aquifer, per unit change in hydraulic head, while remaining fully saturated. Mass specific storage is the mass of water that an aquifer releases from storage, per mass of aquifer, per unit decline in hydraulic head: