Effects of Jointing on Fragmentation Design and Influence of Joints in Small Scale Testing Jonas Hyldahl Civil Engineering, master's level (120 credits) 2018 Luleå University of Technology Department of Civil, Environmental and Natural Resources Engineering Abstract This thesis has been conducted for the Luleå University of Technology (LTU), Sweden as part of an inter-university collaboration between LTU and the Montanuniversität Leoben (MUL), Austria. The project has included three master thesis works, all investigating some aspects of the effects of jointing on fragmentation through small scale tests. The topic of this thesis has been to develop a method for representing/introducing artificial joint planes into concrete blocks and subsequently manufacture a number of specimens with different joint sets for testing, using block dimensions previously used at MUL. The method for manufacturing the jointed test specimens, developed by the author at LTU, has been evaluated through blasting and fragmentation analysis. Comparison of the different produced joint sets has been done to assess the influence of jointing on fragmentation. A total of 10 magnetic concrete blocks were produced and evaluated. The 10 blocks had an average density of 2485 ± 41 kg/m3 (mean ± standard deviation). Eight of the 10 blocks contained joint sets (JS) with different characteristics, while two blocks were un-jointed reference blocks. A total of four different joint sets were developed. The four joint sets had the following properties; JS1: joint spacing 95 mm, strike/dip equal to 0/90°, JS2: joint spacing 47.5 mm, strike/dip equal to 0/90°, JS3: joint spacing 47.5 mm, strike/dip equal to 60°/90° and JS4: joint spacing 89 mm, strike/dip equal to 0/70°. The produced joints have proven to behave as desired, i.e. being able to reflect incident waves and to stop some incident cracks. It has been found that there is a strong indication of jointed blocks producing a finer median fragmentation size (x50) than that of the reference blocks. This means that by introducing joint sets into the test specimens the degree of fragmentation by blasting has been increased. This was predicted by the Kuz-Ram model. Each of the 28 blasted rows has been sieved and analysed. All the data has been fitted to the three parameter Swebrec function, producing an average coefficient of determination (an R- square value) of 0.9946 ± 0.0064. i Preface The mining industry has always fascinated something in me, perhaps the size of the equipment, or the sheer amount of materials moved, but mostly, I think, it is the childish fascination of searching for something in the ground; the feeling of going into the earth, to see and to stand where humanity has never stood before. I fully understand people who, for instance, hate going underground into a tunnel or a mine, but for me, there is something deeply exciting about having hundreds or even thousands of metres of (more or less) solid rock above my head. And thus I have chosen to take, on top of my bachelor degree in civil engineering, a master degree in civil engineering with specialization in mining. So here, 7 years later, this thesis marks the eclipse of my educational journey, a journey which has taken me from Greenland in North to Australia in South, and though this work might mark the end of my academic career, it doesn’t mean that I’m done learning. I would like to thank Nikolaos Petropoulos, my supervisor, and Assistant Professor and Director of Swebrec Daniel Johansson for all their help and support, physically as well as mentally, during my work. Thank you so very much! Also, I would like to thank my fellow students and good friends, especially Patrik Hagström. I doubt, I would have made it through my studies without them. I know it hasn’t always been easy, but thank you for listening and letting me use you for brainstorming and testing ideas as well as a vent for the occasional frustration. Finally, my deepest gratitude to my family and my girlfriend for all their support and love, and for keeping up with me, having lived and studied in four different countries on three different continents, not always being as easy to get a hold of, or see, as they might have preferred. Jonas Hyldahl, September 2015 iii Acknowledgement The author would like to thank Atlas Copco for supplying the financial foundation on which the work for this thesis was build. This was done through the Rock Engineering Price awarded to Professor Finn Ouchterlony. Likewise the author would like to thank Luleå University of Technology (LTU) and Montanuniversität Leoben (MUL) for support and access to facilities. This work was carried out as a joint thesis project between the two universities and, besides the author, also included the two master thesis students Orhan Altürk and Ilke Alp Özer, both writing their theses for Montanuniversität Leoben. The author acknowledges their work with blasting and sieving all the remaining samples after a collective start-up, along with performing P- and S-wave measurements. The author also would like to acknowledge the considerable help from Gerold “Geri” Wölfler, the blast technician at Montanuniversität Leoben, for all his work at the blasting site, as well as Radoslava Ivanova and Peter Schimek for their help and guidance in the early stages of the work with blasting and sieving. Finally the author would like to thank Professor Finn Ouchterlony of the Montanuniversität Leoben for making the project a collaboration between the two universities, thereby making it possible for the author to work with this topic. v List of content Abstract........................................................................................................................................ i Preface ....................................................................................................................................... iii Acknowledgement ...................................................................................................................... v 1 Introduction ........................................................................................................................ 1 2 Literature study ................................................................................................................... 3 2.1 Geology; Joints and Rock Mass Qualification ............................................................. 3 2.2 Fragmentation mechanics ........................................................................................... 5 2.3 Evaluation of fragmentation ........................................................................................ 7 2.3.1 The Kuz-Ram model ............................................................................................. 7 2.3.2 The Swebrec function .......................................................................................... 11 2.4 Previous work; modelling joints in small scale testing .............................................. 13 3 Small scale testing ............................................................................................................. 16 3.1 Model development and preparation ........................................................................ 16 3.2 Cubes .......................................................................................................................... 17 3.2.1 Pull-out times ..................................................................................................... 19 3.3 Magnetic Concrete Blocks.......................................................................................... 20 3.3.1 Reference block design ....................................................................................... 22 3.3.2 Joint set 1 (JS1) ................................................................................................... 24 3.3.3 Joint set 2 (JS2) .................................................................................................. 25 3.3.4 Joint set 3 (JS3) .................................................................................................. 26 3.3.5 Joint set 4 (JS4) .................................................................................................. 28 3.3.6 Joints .................................................................................................................. 29 3.3.7 Potential failures and difficulties ....................................................................... 33 3.4 Magnetic concrete ...................................................................................................... 35 3.4.1 Recipe ................................................................................................................. 35 3.4.2 Density ................................................................................................................ 36 3.4.3 Wave velocity ...................................................................................................... 37 3.5 Expected rock factor (A) according to the Kuz-Ram-model...................................... 41 vii 3.6 Quick guide for making blocks containing joint sets ................................................ 43 3.7 Blasting ...................................................................................................................... 44 3.7.1 Test site Erzberg ................................................................................................. 44 3.7.2 Explosives .........................................................................................................