Estimating of uniaxial compressive strength by using point load index for travertine rock of Mahallat

Document Type : Original Research


1 Department of Mining Engineering, Islamic Azad University - Mahallat Branch, Mahallat, Iran

2 Department of Mining Engineering, Faculty of Graduate Studies, Islamic Azad University of South Tehran, Tehran, Iran


The uniaxial compressive strength (UCS) is one of the most important parameters that is needed and determined for studying rock mechanics of intact rock in most rock engineering projects. In spite of simple appearance of this test, the careful performance is very difficult. Therefore, scientists have made many attempts for indirect estimation of this parameter using simple tests (such as point load index (Is)) and they generated some relations between these parameters. This paper presents the new relationship between UCS and Is by using laboratory tests on Travertine samples of Mahallat. To determine the relations between parameters, the mathematical modeling has been used. Statistical analyses show that the nonlinear equation has a higher correlation coefficient than the linear; also, by estimating another effective parameter, porosity, and by adding it to the last equation, the correlation coefficient between actual and predicted data was improved in multiple non-linear equations. The comparison between actual and predicted results has proved acceptably accurate.