Predictive Mode for Unconsolidated Undrained Shear Strength of Clays Using Artificial Neural Network

Abstract

The shear strength of cohesive soils forms an important engineering property in the design of numerous geotechnical and geo-environmental structures such as earth dams, retaining walls, pavements, liners etc. According to Mohr-Coulomb theory, the shear strength, and#964; of soils varies linearly with the applied stress, and#963; through two shear strength parameters namely cohesion, c and the angle of shearing resistance, and#61542; . In equation form, the shear strength is expressed as: newlineand#964; = c + and#963; tanand#61542;. newlineAccording to the value of applied stress and#963; , as total stress or effective stress, the parameters c and and#61542; may be total stress parameters or the effective stress parameters. The total stress values are used in the situations where short term stability is important and the drainage during the shear is not appreciable. In case of clays unconsolidated undrained shear strength, UU is mostly needed as they have very low permeability and is preferably determined in the laboratory using the triaxial compression test. newlineMany times when the natural soils are poor in some of the properties, they are modified by mixing other types of soils to them. For example, the strength and stability of highly compressible clayey soils can be enhanced by mixing coarse materials like sands and/ or stone dust in different proportions. These mixed soils are known as artificial soils. The components of shear strength namely cohesion and angle of shearing resistance are affected by mixing of coarse particles in to the soils. The other factors such as variation in water content, compaction energy also influences them. Hence, determination of shear strength parameters for artificial soils prepared by mixing different quantity of coarse materials under changing moisture and compaction energy requires testing of huge quantity of samples and thus becomes arduous and time-consuming task and is not always possible on every new situation. Alternate methods have then to be adopted for estimation of the shear strength. newline