Quicksand is not a kind of sand, this is a hydraulic condition.Ī sand soil becomes a ‘quicksand’ when this flow is upward under the hydraulic gradient that reduces the effective stress down to zero. The Boiling condition is quite common at the time when a previous sand stratum that underlies the clay soil is in an artesian pressure condition. Quick Sand condition is prevented by lowering the water table at the site before excavation or by alternatively, increasing the length of the upward flow of water. The excavations in the granular materials behind the cofferdams alongside the rivers.Īny place where the artesian pressures exist i.e., where the head of water is greater than the usual static of the water pressure.īehind the river embankments also in order to protect the floods. The construction sites are very much susceptible to the quicksand type conditions: The person should try to catch some tree on the bank and then try to pull himself out of it. This is to be kept in mind, if a person is caught in this kind of quicksand conditions, he should keep his head high above the soil surface and then move slowly towards the bank. A person might end up dying by drowning, getting suffocated if he gets tired and then let his head fall into this quicksand in a fit of panic. However, the quicksand is very viscous and movement in this would require a high amount of energy. A person can easily float in this with about one-third of his body out of the quicksand. Quicksand fails to support the weight of a man or an animal and thus it behaves like a liquid that has a unit weight that is about twice that of the water. The soil for this phenomenon behaves like a liquid that has no shear strength. If there is a weight being placed on the surface of the soil, it eventually sinks. The discharge then suddenly increases for the increase in the coefficient of the permeability that occurred in the process. At this stage, a violent and visible agitation of these particles occurs. This quick condition in the sand is also known as the boiling condition. When the critical gradient exceeds, the soil here moves upward gradually, and then the soil surface appears to be boiling. This results in the formation of quicksand which cannot support a load on this sand. Quicksand condition occurs when there is a seepage pressure, this acts in the upward direction, while overcoming the downward direction pressure, this is due to the submerged weight of the soil, and here the sand grains are forced out apart. In this situation, the boiling occurs when the excavations are made which is below the water table and at this time the water is pumped out from the excavation pit to keep the area around there free from water. Quicksand condition is actually not a type of soil rather this is a flow condition of the soil that occurs in cohesion less soils. Here the sand boiling occurs, and the bearing capacity and the shear strength of this type of soil decreases, and the agitations of the soil particles are then apparent. Quicksand condition is for the floatation of particles of the cohesion less soil, like the fine gravel and the sand particles, this is due to the vertical upward seepage flow. We will further know about this typical sand situation, the condition of quicksand, its occurrence, and other amazing facts about this sand. Quick Sand is a mixture of sand, mud, and vegetation. Quicksand is found at the mouths of large rivers or along the flat streams or beaches where the pools of water are partly filled with sand with an underlying layer of clay or any kind of dense material that prevents drainage. Quicksand is such a state where the saturated sand loses the capacity to support eventually acquiring the character of a liquid.
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