Quicksand

quicksand

State in which water-saturated sand loses its supporting capacity and acquires the characteristics of a liquid. Quicksand is usually found in a hollow at the mouth of a large river or along a flat stretch of stream or beach where pools of water become partly filled with sand and an underlying layer of stiff clay or other dense material prevents drainage. Mixtures of sand, mud, and vegetation in bogs often act like true quicksands. Any sand may become “quick” if its effective weight is being carried by water between the grains. In that case, even a footstep may collapse the loose structure. The sand-water suspension is denser than an animal or human body, so the body cannot sink below the surface, but struggling may lead to loss of balance and drowning.

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quicksand

a deep mass of loose wet sand that submerges anything on top of it

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quicksand [′kwik‚sand]

(geology)

A highly mobile mass of fine sand consisting of smooth, rounded grains with little tendency to mutual adherence, usually thoroughly saturated with upward-flowing water; tends to yield under pressure and to readily swallow heavy objects on the surface. Also known as running sand.

(materials)

A loose sand mixture with a high proportion of water, thus having a low bearing pressure.

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quicksand

Fine sand, sometimes with an admixture of clay, which is saturated with water so that it has no bearing capacity at its surface; fine sand in a quick condition.

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Quicksand 

sand saturated with water from anabatic sources and capable, consequently, of sucking down objects, animals, and humans falling into it. There are many kinds of quicksand, but all types lack an admixture of silt. Owing to the thin film of water enveloping the grains of sand, adhesion between them is sharply reduced, and quicksand behaves almost like a liquid: submersion of a foreign body continues until the weight of the sand displaced by it is equal to the weight of the body itself. Quicksand is generally confined to the shores of seas, lakes, and rivers (where anabatic sources are usually found), but may occur far from shores in both plains and mountains.

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Quicksand 

water-saturated earth that is able to flow and shift.

Quicksand may be loose or fairly loose sandy loam, finegrained and powdery loose sand, or soil containing colloidal particles less than 0.001 mm in size that act as a lubricant. Quicksand containing colloidal particles is termed true quicksand, according to the classification of the Soviet scientist A. F. Lebedev (1935). The properties of false quicksand, on the other hand, are manifested only under considerable hydrodynamic pressure of the water filtering through it. True quicksand expands greatly when frozen, has low filterability, and becomes cohesive when it dries; microorganisms play a major role in its formation.

Quicksand is controlled by drainage. True quicksand is slow to yield water and therefore vacuuming and electrical drainage are used in draining it. For draining false quicksands, needle filters and tubular wells are used. A soil’s “quick” condition becomes revealed under dynamic stress and with the development of hydrodynamic pressure in the water saturating the soil. The properties of quicksand are taken into consideration in construction and mining projects that make use of shields and caissons and the method of freezing the soil.

M. V. MALYSHEV