TY - THES

T1 - A New Drop Test Rig for Kiirunavaara Mine

AU - Ungerer, Karin

N1 - embargoed until 11-05-2026

PY - 2021

Y1 - 2021

N2 - In order to optimize the energy absorption capabilities of the surface support system, Kiirunavaara mine, owned by LKAB, has constructed a drop test rig. A literature review was done to find out the strengths and weaknesses of previous test rigs and their results. The Kiirunavaara test rig is contextualized using this knowledge. The thinking behind the design is explained, the theory behind the analysis of an experiment is shown. The Kiirunavaara test rig has a drop height of up to 4 m and a maximum drop weight of 1000 kg. Load cells, laser distance measurements, high speed camera footage and multiple accelerometers ensured comprehensive data collection. It is capable of testing round discrete concrete samples with a diameter of 0,8 m and square concrete samples with an edge length of 1,3 m. The square samples are cast on top of large concrete slabs to simulate the adhesion between shotcrete and rock. The impact energy can be varied from 0 to 40 kJ. It is possible to test different types of mesh with varying boundary stiffness and rate of pretension as well as different types of lacing and straps. Concrete, mesh, straps and lacing can be freely combined, therefore it is possible to test various surface support concepts. Single impact and multi impact test were run using both sample types and the response of the samples was recorded. The results of the conducted experiments are shown and analysed. The important findings are that concrete thickness has some influence on its energy absorption potential. Thin spray-on liner appears to perform poorly and that chain-link mesh outperforms welded mesh. Fibre reinforced shotcrete supports chain-link mesh and drastically increases its energy absorption capabilities. Lastly future modification that could be done to make the rig more comprehensive are discussed, for example, being able to conduct dynamic tests on bolts, quasistatic tests on surface support or dynamic tests on complete support systems.

AB - In order to optimize the energy absorption capabilities of the surface support system, Kiirunavaara mine, owned by LKAB, has constructed a drop test rig. A literature review was done to find out the strengths and weaknesses of previous test rigs and their results. The Kiirunavaara test rig is contextualized using this knowledge. The thinking behind the design is explained, the theory behind the analysis of an experiment is shown. The Kiirunavaara test rig has a drop height of up to 4 m and a maximum drop weight of 1000 kg. Load cells, laser distance measurements, high speed camera footage and multiple accelerometers ensured comprehensive data collection. It is capable of testing round discrete concrete samples with a diameter of 0,8 m and square concrete samples with an edge length of 1,3 m. The square samples are cast on top of large concrete slabs to simulate the adhesion between shotcrete and rock. The impact energy can be varied from 0 to 40 kJ. It is possible to test different types of mesh with varying boundary stiffness and rate of pretension as well as different types of lacing and straps. Concrete, mesh, straps and lacing can be freely combined, therefore it is possible to test various surface support concepts. Single impact and multi impact test were run using both sample types and the response of the samples was recorded. The results of the conducted experiments are shown and analysed. The important findings are that concrete thickness has some influence on its energy absorption potential. Thin spray-on liner appears to perform poorly and that chain-link mesh outperforms welded mesh. Fibre reinforced shotcrete supports chain-link mesh and drastically increases its energy absorption capabilities. Lastly future modification that could be done to make the rig more comprehensive are discussed, for example, being able to conduct dynamic tests on bolts, quasistatic tests on surface support or dynamic tests on complete support systems.

KW - drop test

KW - surface support

KW - kiruna

KW - rock burst

KW - shotcrete

KW - dynamic

KW - seismic event

KW - TSL

KW - thin spray-on liner

KW - welded mesh

KW - chain-link mesh

KW - FRS

KW - fibre-reinforced concrete

KW - FPS

KW - frames pre second

KW - high speed camera

KW - lacing

KW - lace

KW - lashing

KW - dynamic loading : dynamic testing

KW - ausbau

KW - gebirgsschlag

KW - kiruna

KW - maschendraht

KW - lacing

KW - baustahl

KW - spritzbeton

KW - fallversuche

KW - dynamisch

KW - dynamische Belastungen

KW - Kiruna

KW - TSL

KW - hochgeschwindigkeitskamera

KW - FPS

M3 - Master's Thesis

ER -