| Summary: | The core justification of this thesis was to delay expected failures by means of studying different sequencing patterns. This thesis reviews, analyzes and compares some of extraction methods and sequences used in steep orebodies. The subject of the research was proposed and supported by Boliden Mines and was conducted as a Master thesis in Luleå University of Technology.Models were calibrated using data from observed failures on levels 880, 896 and 926 in Lappberget orebody. Hoek-Brown criterion with modified parameters for brittle rock and Stacey’s extension criterion were used in the process of analysis.One major objective of the thesis is to decide the size of the stopes. For the purpose of comparison an index for crack propagation depth was introduced, the origin of the index is ELRD (equivalent linear relaxation depth) which was proposed as a tool to quantify the relaxation zone around excavations. Some modification was done on ELRD so it can be used for the goals of the project. Six variation of stope dimension was modeled in an isolated model. The comparison of stope dimension was studied in different sequencing patterns as well.Finally, seven different sequencing methods were suggested and studied for exploiting the ore. The sequencing methods include primary-secondary patterns with three alterations of stope size, tertiary patterns with two variations of stope size, a pillarless pattern and a twoway pattern (top-down and bottom-up). Validerat; 20121024 (anonymous)
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