Prediction of some geotechnical properties of deltaic clays: using regression analysis models

Abstract

Establishment of any engineering structure on a compressible clay leads to settlement and/or failure through this clay. The amount of this settlement is controlled mainly by the compressibility parameters, while the failure by the undrained strength. The measuring of compressibility parameters and undrained strength are expensive, cumbersome, and time-consuming; therefore several attempts have been made to predict these geotechnical parameters by using simple, cheap, and time-saving index properties of the soil. In this study, the performance of applying empirical equations for the estimation of these critical geotechnical parameters was assessed by using a database including 551 undisturbed samples of the Nile Delta clay. The regression analysis results depict statistically moderate to strong correlations exist between both compression index and recompression index and the bulk density, Atterberg limits, initial void ratio, and effective overburden pressure. The precompression stress, overconsolidation ratio, and undrained shear strength parameters have no remarkable correlations with these index properties, except the effective overburden pressure parameter that has moderate to strong correlations with these properties. The compressibility and strength parameters depend on the in-situ effective stress, stress during geological history, diagenesis and cementation process, mineralogy, microstructure, and texture of clay, therefore they provide meaningful relationships. The developed empirical equations in this study, which derived from various linear and multi-variables regression models, are reliable and capable to predict the geotechnical design parameters with high prediction performance.