Effect of Fines on Liquefaction Resistance in Fine Sand and Silty Sand

It is required to recognize the conditions that exist in a soil deposit before an earthquake in order to identify\ud liquefaction. Soil is basically an assemblage of many soil particles which stay in contact with many neighboring\ud soil. The contact forces produced by the weight of the overlying particles holds individual soil particle in its\ud place and provide strength. Occurrence of liquefaction is the result of rapid load application and break down of\ud the loose and saturated sand and the loosely-packed individual soil particles tries to move into a denser\ud configuration. However, there is not enough time for the pore-water of the soil to be squeezed out in case of\ud earthquake. Instead, the water is trapped and prevents the soil particles from moving closer together. Thus, there\ud is an increase in water pressure which reduces the contact forces between the individual soil particles causing\ud softening and weakening of soil deposit. In extreme conditions, the soil particles may lose contact with each\ud other due to the increased pore-water pressure. In such cases, the soil will have very little strength, and will\ud behave more like a liquid than a solid - hence, the name "liquefaction"