Estimation of Soil Permeability using Soil Index Properties

Permeability is a very important engineering property of soils and finds utility in a number of soil engineering problems such as yield of wells and seepage through and below the earth structures. It controls the hydraulic stability of soil masses. The permeability of soils is also required in the design of filters required to prevent piping in hydraulic structures. However, the determination of soil permeability is a cumbersome and time consuming process, especially in the case of fine grained soils. The permeability of soils depend upon the particle size, structure of soil mass, shape of soil particles, void ratio and properties of permeate. However, the major factors which determines the value of permeability are particle size and void ratio. Several models are available in literature which relate permeability to particle size only. In the present study, an attempt has been made to estimate permeability of soils as a function of soil grain size and void ratio. Soil samples were collected from different Indian hydropower projects. The collected samples were subjected to laboratory investigations for the determination of geotechnical parameters namely specific gravity, maximum dry density, void ratio, grain size distribution and coefficient of permeability. An empirical model was developed for the determination of soil permeability as function of soil grain sizes and void ratios, using regression analysis. The model results were compared with the actual permeability values, as determined by laboratory tests. The results indicate that the present model can predict the soil permeability better than the existing models and the mean absolute percentage errors and root mean square errors are less than the present models.