Influence of Initial Conditions on Undrained Response of Soft Clays

Soft soils are found along east and west coast of Kerala. They exhibit unusual engineering properties like high natural water content, high compressibility, low permeability and low shear strength. Availability of land for the development of commercial, housing, industrial and transportation, infrastructure, etc., is getting scarce nowadays. This necessitated the use of land, which has weak strata, wherein the geotechnical engineers are challenged by the presence of different problematic soils with varied engineering characteristics. Not much work has been done to understand the behaviour of these soils. Hence, it is necessary to study the geotechnical behaviour of such soils including the effect of various parameters. As far as Kerala is considered, soft clays are predominant in Kuttanad and greater parts of Cochin. Research works carried on Kuttanad clay and Cochin marine clay mainly focused on compaction, compressibility and UCC strength. Clayey soils are impervious and do not permit drainage of water. There will be a cumulative build-up of pore water leading to increase in pore water pressure and reduction in shear strength, finally leading to increase in settlement and deformation. Not much works have been done on laboratory modelling of the soft clays of Kerala and its behaviour under the influence of varying parameters. Soil properties vary from point to point due to the variations of field parameters. The objective of this paper is to investigate the effect of various parameters influencing undrained behaviour of Kuttanad clay. Confining stress and density were studied. For this purpose, consolidated undrained triaxial test was performed with pore pressure measurements. Typical deviator stress-strain graphs, pore pressure versus strain graphs, and stress paths were drawn for all the tests conducted.