Water Saturation Influences on Engineering Properties of Selected Sedimentary Rocks of Pakistan

Abstract

This study is focused on the evaluation of water saturation influence on the mechanical and physical properties of 34 sedimentary rock units selected from different geological formations in Pakistan. The laboratory testing program comprised the determination of physico-mechanical rock properties of both air-dry as well as fully water saturated rock specimens. Further thin section analyses of all rock samples were also performed to explain their petrography. According to the statistical analyses overall reductions of around 40 and 50% were found in UCS_sat and BTS_sat values, respectively, measured on saturated rock samples in comparison to their corresponding dry strength values, i.e. UCS_dry and BTS_dry. Linear correlations were found between ultrasonic wave velocities as well as density of both dry and saturated rock samples. In addition, the dry and saturated UCS values were exponentially related with the rock porosity. Multiple regression technique was also utilized to develop a predictive linear model of UCS_sat with geotechnical rock properties in the dry condition and petrographical characteristics of rock samples. Finally the validity of multiple regression model developed in this study and an existing correlation for the conversion of UCS_dry into UCS_sat was statistically assessed.