Standardized Process for Filed Estimation of Unconfined Compressive Strength Using Leeb Hardness

Abstract

An investigation of the statistical relationship between Leeb Hardness (“D” type) values (HLD) and unconfined compressive strength values (UCS) for different rock types was conducted. The Leeb hardness test (LHT) procedure was evaluated by investigating the sample size effect on HLD values and the optimum number of impacts that are required to get a reasonable measure of the hardness of the rock specimen. For improving the UCS- HLD correlation, the laboratory testing was carried out on rock specimens and combined with other literature values to develop a database with a total of 311 UCS and HLD results. Statistical analysis was carried out on the database. The predictions of the results of correlation analysis from the tests are presented. A reasonable correlation was found to exist between HLD and UCS. The findings from these evaluations will improve the UCS prediction and the LHT procedure.