Geotechnical risk assessment in the Pyhäsalmi mine with a focus on seismic risk

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Insinööritieteiden korkeakoulu | Master's thesis
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Date

2014-08-25

Department

Major/Subject

European Mining Course (EMC)

Mcode

R3008

Degree programme

Master’s Degree Programme in Minerals and Environmental Engineering

Language

en

Pages

79+37

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Abstract

Due to a constant depletion of shallower deposits underground mining is pushing production to larger depths resulting in more difficult ground conditions and an increase of rock stresses. Mining at larger depth effects in an increase in seismic activity, therefore seismic risk is becoming more important and requires special attention. This necessitates development of frameworks and guidelines to tackle those risks more efficiently. The scope of this study was to apply and test the Geotechnical Risk Assessment guideline for underground mines developed at Aalto University as part of the project: Innovative Technologies and Concepts for the Intelligent Deep Mine of the Future (I2mine), work package 3 - “Rock mechanics and ground control”, under the 7th framework of the European Union. The goal was to use seismic monitoring data from the Pyhäsalmi mine in order to quantify the seismic risk, using proposed guideline as a framework for evaluation. Furthermore, the research was aimed to give answers on: what is the applicability of the guideline, what are the main issues encountered during its usage and how to improve it. Geotechnical Hazard Potential was evaluated using a proposed methodology. Next, seismic risk in the Pyhäsalmi mine was assessed. Seismic events from the database were clustered into logical groups in order to speed up the analysis. Then, the maximum predicted size of a seismic event was found for each cluster group. Seismic risk was assessed based on the largest possible seismic event attributable with a particular damage that is expected. The final risk was evaluated using two methodologies: one that is currently used in the mining industry and second under the development. The level of seismic risk in the Pyhäsalmi mine was found to be low. The biggest risk was found in areas located at the northern ore-waste contact zone. Installation of additional ground support was recommended in order to lower the risk. The Geotechnical Risk Assessment guideline was found to be suitable framework for risk assessment purposes, which supports in selection of appropriate assessment approach and aids in selection of tools that are used throughout the evaluation. Its applicability was found to be high, however minor changes were recommended in order to use its full functionality.

Description

Supervisor

Rinne, Mikael

Thesis advisor

Wen, Zhijie

Keywords

mining, risk assessment, seismic hazard, Pyhäsalmi mine

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https://urn.fi/URN:NBN:fi:aalto-201408292548

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[dipl] Insinööritieteiden korkeakoulu / ENG