Permeability of Stratified Soils for Flow Normal to Bedding Plane

Abstract Permeability of porous media is an important property which depends upon various properties of soil mass such as porosity, size and shape of soil particles, initial moisture content and compaction etc. As in natural condition, the soil mass exists in layers/ strata, thus represents a stratified soil. The flow through stratified soil may be perpendicular, inclined or parallel to the bedding plane. In this paper an attempt has been made to study the behavior of double layered stratified soil samples of equal thickness subjected to a flow perpendicular to the bedding plane in terms of its permeability. The materials used in the study were sand, fly ash, silt and clay. The observed values of permeability under several arrangements of layers were determined. In all the considered arrangements, observed permeability was found to be less than the corresponding theoretical values by 20 to 50 percent. A comparison was also made between the results obtained in the present study and that available in literature, a good agreement has been observed. It was further noticed that if exit layer is less pervious than the top layer, the observed permeability of the stratified soil has been found to be more as compared to the permeability of isolated exit layer by 33% to 54%. If exit layer is more pervious than the top layer, the permeability of the stratified soil has been observed to be less as compared to the isolated permeability of exit layer by 87% to 100%.