Estimation of uniaxial compressive and indirect tensile strengths of intact rock from Schmidt hammer rebound number

Abstract

Abstract A number of destructive and non-destructive tests were conducted on rock samples collected from various zones in northern Iraq. So far, for Iraqi rocks, few studies have correlated Schmidt hammer rebound (R) with both unconfined compressive strength (UCS) and Brazilian tensile strength (BTS). In this study, the objective is to develop a relationship between the rebound number of Schmidt hammer surface hardness (rebound number) and both the BTS and the unconfined compressive strength (UCS) of different types of northern Iraqi rocks. The required relationship should be based on measured values of the UCS, BT, and Schmidt hammer hardness. To determine the relationship between R and both the UCS and BTS, 120 intact rock samples were prepared and tested using a uniaxial compressive test machine, a Brazilian test apparatus, and an L-type Schmidt hammer test (BTS). Three different types of rock samples (sandstone, claystone, and limestone) were collected from several locations in northern Iraq (Domeez, Baadra, and Zawita). For the three types of rocks, a new linear correlation with a high value of the regression coefficient R 2 is presented, linking the UCS and BTS separately versus R. For the three types of rocks studied, the correlation between UCS and R is better than the correlation between Brazilian tensile strength (BTS) and R.