Experimental and numerical investigations of impact splitting of naturally bedded layered slate rock

In this thesis investigation, experimental and numerical studies were carried out to determine the axial impact splitting loads and the splitting process of naturally bedded layered slate rocks. This effort was undertaken to examine an alternate slate mining procedure so that the wastage in slate can be reduced from the present-day 95%. This was the first effort made in the use of this procedure for slate excavation.; Experimental impact forces were determined by carrying out splitting tests on different sizes of slate blocks from small to intermediate scales, using a hydraulic actuator with a wedge-shaped indenter in the laboratory. Generally the slate blocks split parallel to their natural bedding planes, exhibiting clean and even split faces. Thus the use of this procedure for slate mining will minimize the damage produced by the use of optimum explosives; this reduction in wastage has been approximately estimated to be nearly 20% to 25% less than the present-day 95%. It has been observed in some cases that breaking loads were not consistent with the sizes of blocks (probably due to the presence of pre-existing flaws within the block). Some of the larger blocks needed lesser loads to break than those found for relatively smaller blocks.; Numerical analyses were carried out to predict the impact splitting loads required to split a finite sized layered slate rock based on the observed mechanism of plane crack propagation in plane strain and three-dimensional slate blocks, obtained from impact splitting of slate blocks in the laboratory. In order to characterize the material for numerical analysis, properties of the slate material, such as elastic moduli, Poisson's ratio, compressive and tensile strengths, coefficient of friction (between slate and steel), plane strain fracture toughness, hardness, crack propagation velocity etc., were determined after carrying out extensive experimental investigations. The experimental values obtained in this study were generally within the ranges specified for slates of other origins. It must also be mentioned here that the results presented in this thesis on the physical and mechanical properties of slate are the first study carried out on slates of Newfoundland origin.; ABAQUS finite element software was used to simulate the entire wedge impact splitting process during numerical analysis. Mode I (plane strain opening mode) dynamic crack propagation was simulated numerically by the sequential releasing of the restraining node on the symmetric plane of the analyzed specimen. (Abstract shortened by UMI.)...