Geotechnical properties of fine-grained soils in Ankara/Turkey: an assessment of the existing empirical equations

摘要

The primary purpose of this study is to determine the geotechnical properties of fine-grained soils of Ankara. The secondary purpose is to determine the statistical relationships among swelling potential, swelling pressure and geotechnical parameters of these fine-grained soils. 440 data sets were used. Standard penetration tests, swelling tests and index tests were performed in this study. Fine-grained soils of Ankara are mainly medium-high plastic inorganic clays. They are mainly moderately active and stiff. Ankara soils may be considered as medium to high expanding soils and may be risky for lightweight structures. The simple regression analyses between swelling pressure and plasticity index resulted in a high coefficient of determination. The simple regression analysis among swelling potential and activity, swelling pressure and fine-grained percentage also resulted in an acceptable coefficient of determination. Two input parameters were used for the multiple nonlinear regression analysis. The prediction performance of the derived equations was tested with RMSE indices and VAF values. The best predictions were determined with the equation derived with the corrected SPT blow count-activity as an input parameter for determination of the swelling potential and the corrected SPT blow count-fine-grained percentage for determination of the swelling pressure with the multiple nonlinear regression analysis. Prediction error analysis of empirical equations proposed in this study and empirical equations collected from literature were performed. Both the equations proposed in this study and several equations from literature showed good performance. However most of the equations from literature gave negative results. The empirical equations developed in this study should be tested with other studies.