Predicting Soil Compressive Strength of Sulaimani Governorate, Iraq

Abstract

Soils shear strength is one of the significant properties for geotechnical engineering purposes. Shear strength components, cohesion and angle of internal friction, are used in soil’s bearing capacity determination, which is the key factor in construction developments. Unconfined compression test is a common type of soil shear testing to obtain the unconfined compressive strength (UCS) and cohesion (C). UCS is a widely-used soil’s geotechnical characteristic for design and practice of soil foundation of construction projects. The laboratory determination of UCS is tiresome, which requires very-accurately prepared field sample and in some way a time-consuming, the purpose of this study is established. This study is aimed to establish a prediction model for Sulaimani soils UCS determination via using multiple linear regression methods. Models were created from undisturbed fine-grained soil samples collected from three different locations at Sulaimani Governorate in Kurdistan Region of Iraq. The precision of the established equations is tested by utilizing three different versions of coefficient of determinations namely R², adjusted-R² and predicted-R². Box-Cox statistical transformation of data enhanced the performance of the regression models.  The results showed a reliability of the transformed-data regression model to predict UCS with R² of 0.80, R²_-adjusted of 0.80 and R²_-predicted of 0.77.