The Role Of Ultrasonic Velocity And Schmidt Hammer Hardness - The Simple And Economical Non-Destructive Test For The Evaluation Of Mechanical Properties Of Weathered Granite

摘要

One of the most significant techniques for evaluation of rock strength is by using the simple and economical non-destructive test (NDT). Previous literatures confirm that there were good correlations between NDTs to the strength properties of granite rocks. The present work deals with the use of Ultrasonic Pulse Velocity and Schmidt Hammer Hardness test to predict the mechanical properties of weathered granite. Cylindrical specimens with the length to diameter ratio of two were prepared for this study and were characterized based on different weathering states. Each of the rock specimens was tested under non-destructive test and then followed by uniaxial compression test to assess the mechanical properties. It was found that good correlations established between the NDTs and the uniaxial compressive strength. The correlation between uniaxial compressive strength and rebound hardness number was demonstrated by exponential form; UCS= 6.31e~(0 .057N), while linear correlations was obtained between the uniaxial compressive strength and the ultrasonic pulse velocity; UCS= 0.023Vp - 21.43. It was also noticed that the increase of uniaxial compression strength was parallel to the increase of elastic modulus and can be presented by a linear equation; UCS= 1.039Et50 + 4.252. Based on the reported results, it is clear that the mechanical properties or weathered granite can be estimated by means of non-destructive test.