TY - THES

T1 - Development of a blasting area and blasting tests with concrete blocks in half scale to research different fragmentation phenomena

AU - Maierhofer, Erhard

N1 - embargoed until null

PY - 2011

Y1 - 2011

N2 - To better understand blast fragmentation, a new experimental blast site at the “Styrian Erzberg” was realized by the University of Leoben. The goal of this work was to get a better understanding of the fragmentation of concrete blocks through blasting in laboratory scale and half scale. For this reason, a blasting area was established, which allows blasting of concrete blocks in half scale, collecting the resulting excavated material without secondary mechanical crushing and subjecting it to a variety of analysis. A blasting enclosure was built consisting of steel uprights, a wire mesh fence and multiple layers of blasting mats. The following tests attempted to achieve a "good" blasting result, by varying the geometrical factors like burden, spacing, drill hole diameter and amount of explosives. Before that, the material properties of the concrete blocks in half scale were analyzed, by means of test explosions of concrete blocks in laboratory scale, which consisted of the same concrete mixture. For this purpose, cubes with varying edge lengths were detonated and a sieve analysis was carried out. In the subsequent experiments half scale concrete blocks with a size of 2 m³ were blasted. The burden and spacing was varied and the excavated material was subjected to sieve and graphical analysis. As result of the work sieving curves were established for each experiment. Further, the influence of the geometry in the half scale tests was studied. In these first tests it could be seen that there is a good relation between energy input and fragmentation. For further blasting tests, smaller test blocks which are in a solid bond to the blast site, are recommended.

AB - To better understand blast fragmentation, a new experimental blast site at the “Styrian Erzberg” was realized by the University of Leoben. The goal of this work was to get a better understanding of the fragmentation of concrete blocks through blasting in laboratory scale and half scale. For this reason, a blasting area was established, which allows blasting of concrete blocks in half scale, collecting the resulting excavated material without secondary mechanical crushing and subjecting it to a variety of analysis. A blasting enclosure was built consisting of steel uprights, a wire mesh fence and multiple layers of blasting mats. The following tests attempted to achieve a "good" blasting result, by varying the geometrical factors like burden, spacing, drill hole diameter and amount of explosives. Before that, the material properties of the concrete blocks in half scale were analyzed, by means of test explosions of concrete blocks in laboratory scale, which consisted of the same concrete mixture. For this purpose, cubes with varying edge lengths were detonated and a sieve analysis was carried out. In the subsequent experiments half scale concrete blocks with a size of 2 m³ were blasted. The burden and spacing was varied and the excavated material was subjected to sieve and graphical analysis. As result of the work sieving curves were established for each experiment. Further, the influence of the geometry in the half scale tests was studied. In these first tests it could be seen that there is a good relation between energy input and fragmentation. For further blasting tests, smaller test blocks which are in a solid bond to the blast site, are recommended.

KW - blasting

KW - laboratory scale

KW - half scale

KW - influence of the geometry

KW - fragmentation

KW - Sprengen

KW - Halbmaßstab

KW - Labormaßstab

KW - Sprenggeometrie

KW - Zerkleinerung

M3 - Master's Thesis

ER -