Thesis (PhD) - Cyprus International University. Institute of Graduate Studies and Research Civil Engineering

This dissertation focuses on the investigation of clayey soils of Cyprus to derive a
statistical model describing degree of plasticity and to determine correlations between
soil properties as well as the geological formations. Physical properties data from 211
different soils from the geotechnical literature of Cyprus within highly plastic range
have been utilized to create a model to predict the degree of plasticity of soils by using
mainly factor and regression analyses. Collected soil properties were integrated into
the study, which include liquid and plastic limits, clay fraction, montmorillonite and
calcium carbonate contents. Based on these properties a comprehensive statistical
study was conducted by utilizing different statistical concepts. These are the measures
of central tendency, variability, position, and distribution shapes. Frequency
distribution of the soils was also examined. Various findings were noted, and
discussions have been made based on this investigation. Some of these properties have
an increasing influence on soil plasticity while others have an indirect effect. The
differences in plasticity characteristics of clayey soils were identified and discussed by
using factor analysis. The statistical model was created to predict the degree of
plasticity simply by using plasticity index which is constituted of a single expression
with six ranges of the degree of plasticity for easy and broader application. The
relationships between the soil properties were studied and empirical equations were
proposed. Similarities and differences of clayey soils of Cyprus were discussed and
geological formations of the investigated soils were characterized.