An Interpretation of Experimental Data of Routine Field Investigation in Regional Soils to Predict the Undrained Shear Behaviour

Urban conglomerations are leading to enhanced building activity in soils of less competent nature. Further infrastructure projects encompassing commercial centers, bridges, flyovers , water supply and irrigation structures, air ways and road ways are planned in quick succession to enable smooth flow of commercial operations needed to make pace with global economy. The situation is prompting geotechnical engineer to devise means and methods to understand rapidly the mechanical response of the soils in a unified and comprehensive manner, based on testing done on miniature representation of the whole system of soil. Routine geotechnical investigations are taken up to conduct filed and laboratory testing in order to interpret the data to propose design parameters for making necessary stability and strength computations in order to facilitate design calculations for the field engineers.An experimental investigation is taken up on field soil samples obtained from 16 different depths at different locations from Tirupati surroundings. Tests are conducted to obtain basic properties of soils apart from undrained shear tests to evaluate shear parameters. A common way of determining the shear strength of clayey soil is to extract undisturbed samples and subject them to undrained compression without allowing to consolidate in triaxial compression. Shear strength is expressed in terms of cu and ϕu for partly saturated samples. A field penetration test is used for evaluating and interpreting the field characteristics. The data of soil samples obtained from different location are used for prediction purposes. The interpretation based on analysis of the data using state parameter approach and field penetration data provides a framework to evaluate design parameters