Correlation Between Uniaxial Compressive Strength and Brazilian Tensile Strength Using Different Rock Types
Pâmmela Caroline Pinazzi da Silva Ribeiro1; Michel Melo Oliveira1; Priscilla P. Nelson2
1 Centro Federal de Educação Tecnológica de Minas Gerais; 2 Colorado School of Mines
Resumo
The Uniaxial Compressive Strength (UCS) is widely used for professionals who work in designing surface or underground excavations. This parameter is used to determine rock properties and characteristics. Moreover, it is important not only to analyze but also to study the rock in geological and geotechnical perspectives. The Uniaxial Compressive Strength of intact rock is a necessary input for the estimation of rock mass strength criterion. However, the UCS test is very expensive and also it involves some issues as demanding high quality samples. Thus, this parameter is often determined based on other parameters as Brazilian Tensile Strength (BTS) and Point Load (PL). Previous scientific studies indicated that the BTS relates better with UCS than PL. Thus, this study is being carried out to figure out a linear equation that better correlates UCS and BTS for each rock type and a general equation for all of them. Also, it analyzes the previous studies of this correlation and compares them. This study was developed based on bibliography reviewing and analyzing the database of Earth Mechanics Institute (EMI) at Colorado School of Mines (CSM). These data have been collected in the last 40 years; it came from laboratory experiments conducted at EMI. It was chosen 30 values of UCS and 30 values of BTS tests. A linear regression was used to analyze this data. From that, the rocks chosen were granite, gneiss, and sandstone, which are igneous, metamorphic, and sedimentary rocks, respectively. Another parameter analyzed in this paper was the ratio between BTS and UCS, which is another way of relating these parameters. The average ratio between UCS and BTS found was about 13, for the three types of rocks. Analyzing separately, this ratio for igneous, metamorphic, and sedimentary rocks, were 15, 12, and 12, respectively. Also, a comparison between the UCS determined in the laboratory and the UCS predicted by the equations found was made. After analyzing these many data, it was found a linear correlation between UCS and BTS. T
Palavras-chave: Uniaxial Compressive Strength; Brazilian Tensile Strength; Linear Correlation