Soil mechanics

right|thumb|upright=1.5|An illustration showing groundwater in aquifers (in blue) (1, 5 and 6) below the [[water table (4), and three different wells (7, 8 and 9) dug to reach it.]]

thumb|right|Quicksand and a warning sign about it at a gravel quarry in England thumb|Quicksand on the River Thames|Thames Quicksand, also known as sinking sand, is a colloid consisting of fine granular material (such as sand, silt or clay) and water. It forms in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape, it creates a liquefied soil that loses strength and cannot support weight. Quicksand can form in standing water or in upward flowing water (as from an artesian spring). In the case of upward-flowing water, forces oppose the force of gravity

weight per volume of a material

Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure the "accessible void", the total amount of void space accessible from the surface (cf. closed-cell foam).

branch of soil physics and applied mechanics that describes the behavior of soils

geological phenomenon when soil material that is ordinarily a solid behaves like a liquid

equation describing the flow of a fluid through a porous medium

thumb|Mānuka honey is an example of a thixotropic material. Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow (become thinner, less viscous) over time when shaken, agitated, shear-stressed, or otherwise stressed (time-dependent viscosity). They then take a fixed time to return to a more viscous state. Some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite tim

thumb|300px|Subsided house, called The Crooked House, the result of 19th-century mining subsidence in [[Staffordshire, England]] thumb|A625 road#Mam Tor road|Mam Tor road destroyed by subsidence and shear, near Castleton, [[Derbyshire]]

(of a granular material) steepest angle of descent or dip relative to the horizontal plane to which a material can be piled without slumping. At this angle, the material on the slope face is on the verge of sliding

measure of the ability of a porous material to allow fluids to pass through it

process by which soils decrease in volume

the unsaturated aquifer above the water table

quantity of water contained in a material

geomorphic process by which soil, sand, regolith, and rock move downslope

theoretical and applied science of the mechanical behavior of rock and rock masses; compared to geology

measure of the ability of a porous material to allow water to pass through it

results from ice forming beneath the surface of soil during freezing conditions

gas produced naturally within marshes, swamps and bogs

process of infiltration and percolation of water in the ground and aquifers

unit of permeability

mathematical model describing the response of a brittle material to mechanical stresses and to define shear strength of soils and rocks

type of glaciomarine clay

pressure of soil in horizontal direction

pressure of groundwater held within a soil or rock, in gaps between particles

volume occupied by liquid and gas phases in a soil

capacity of soil to support loads

cone of sand formed by the ejection of sand onto a surface from a central point by water under pressure

Physical quantity in soil

liquids that were trapped in the pores of sedimentary rocks

volume change of a granular material under shearing

dimensionless quantity related to porosity

part of shear strength that is independent of the normal effective stress in mass movements

Magnitude of the shear stress that a soil can sustain

stress imposed on soil or rock by overlying material

Type of graph

Sinking of land due to groundwater extraction

thin layer of water surrounding mineral surfaces

depth to which the groundwater in soil is expected to freeze

conjectural soil type probably not found in nature

consists of the interaction between soil and a structure built upon it

soil type

concept in physics

the amount of water that a portion of an aquifer releases from storage, per unit mass or volume of aquifer, per unit change in hydraulic head