STATISTICAL STUDY OF INTACT ROCK’S PHYSICAL AND MECHANICAL PROPERTIES IN INDONESIA

• Main Author: Sailendra, Ahmad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/57834
• Institution: Institut Teknologi Bandung

An engineer will always face all possible uncertainties in physical and mechanical properties of the rocks that arise due to the unavailability of the required data and data variations. The physical and mechanical properties of the rocks can be estimated by the theory of probability distribution functions and statistical correlations and the results can help to subdue the existing uncertainties. In this study, a study was conducted in the form of the best statistical distribution of random variables in which we can obtain the estimated parameter values.. Then, the relationship between physical properties and mechanical properties of the rocks will be determined by regression analysis and the estimated parameter values will be obtained through the obtained regression equation. The results of the estimated parameters that will be found for geotechnical applications on the Safety Factor (SF) and Probability of Failure (PoF). The results from determining the best distribution show that the dominant distribution in igneous rocks is a normal distribution with a percentage by 54.54%, in metamorphic rocks a triangular distribution with a percentage by 38.46%, and in sedimentary rocks a beta distribution with a percentage by 42.10 %. From the results of correlation analysis, the parameters of rock physical properties that most influence the mechanical property parameters of rock are bulk density, porosity, and degree of saturation with a correlation level by 0.459 - 0.989 and a coefficient of determination by 0.21 - 0.978 and mechanical properties that are closely correlated are UCS and Young's modulus with a correlation level by 0.897 – 0.961 and a coefficient of determination by 0.806 – 0.924. Then, in the geotechnical application there is a percentage difference from the results of the calculation of SF and PoF with the assumption of a normal distribution and the results of the study with the percentage difference in SF by 0,95% - 4,13% and PK by 32,48% - 87,5% and there is a percentage difference in SF deterministic and statistical by 3,08% - 6,93%. This can affect the accuracy of the calculation results of the Safety Factor (SF) and the Probability of Failure (PoF) which results in mining safety.