Estimation of rock mass rating values with geostatistical analysis

Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Graduate School of Natural and Applied Sciences, Maden Mühendisliği, Turkey

Approval Date: 2019

Thesis Language: English


Supervisor: Mustafa Erkayaoğlu


The raw material of many goods, products, and equipment used by humankind on earth or even in space are obtained from extracted and enriched minerals from the surface or underground mines. A large proportion of the energy produced and used worldwide are derived from carbon-containing materials that are extracted from mining operations. This points out that the demand for these materials is not expected to decrease for human beings to sustain their existence on earth and may be in space. As this requirement continues and increases, underground mines will be continued to be operated. The geological properties of rock material are taken as the basis of exploration for a mine deposit. After that, drillings are made in order to find out the answers to the following questions: “What is the grade of the deposit?”, “How economic and appropriate is the deposit for the extraction?”, and “Is it suitable for mineral processing?”. Drilling costs are one of the major investment expenses of a mining project. Depending on the depth and extension of the mineral source, these drilling costs might increase as well. This thesis study aims to provide an estimation of Rock Mass Rating values with the minimum number of drill holes in a mine site in order to decrease the drilling costs. The sub-objectives of this study are: i) acquisition and preparation of the data from Sivişli and Şelale project, ii) modeling semivariogram and kriging, iii) evaluating and analyzing the estimation results with cross-validation. In order to accomplish these objectives, semivariogram and Kriging estimations of RMR data were carried out in Micromine software. The comparison of the mean values was selected for the major evaluation factor of RMR estimation. According to the comparison of means, the OK estimation method gives more realistic results than IDW estimation in two regions, and the mean of OK estimation using estimated range value was closer than other OK estimation in the same region. This study does not propose an alternative to rock mass quality determination methodology but introduces an implementation that can be utilized for cases where geotechnical drilling is limited. The main contribution of this study is that the information gained from kriging can be used in accordance with the grade estimation block model for mine planning purposes.