Academic literature on the topic 'Mining engineering Rock mechanics. Rock excavation. Mineral industries'

The open-pit mining slopes continue to become higher and steeper with the continuous exploitation of near-surface mineral resources. The blasting excavation exerts a significance influence on the slope stability. In fact, intact rock slopes do not exist and slope stability is controlled by the geological defects. In this paper, the stability of a rock slope imbedded with a fault is considered. The P-wave component of blasting seismic waves is focused on and the fault is simplified as a semi-infinite crack. In background of Daye iron mine, the peak particle velocity (PPV) threshold is determined based on the linear elastic fracture dynamics. The influence of frequency, Young's modulus, and Poisson's ratio is studied to modify the PPV threshold. Results show that (1) the PPV threshold decreases with the increasing Young's modulus and Poisson's ratio, but increases with the increasing frequency; (2) the initiation angle is immune to Young's modulus and the frequency, and only depends on the Poisson's ratio; (3) the PPV criterion is finally determined as 1.47 cm/s when the frequency f ≤ 10 Hz, 1.47 cm/s–3.30 cm/s when 10 Hz < f ≤ 50 Hz and 3.37 cm/s–6.59 cm/s when f > 50 Hz, which are far less than that of intact rock slopes; (4) The north slope is quite safe if the proposed PPV threshold is not violated due to the variation range of the initiation angle θ0.

Recently, engineering blasting is widely applied in projects such as rock mineral mining, construction of underground cavities and field-leveling excavation. Dynamic mechanical performance of rocks has been gradually attached importance both in China and abroad. Concrete and rock are two kinds of the most frequently used engineering materials and also frequently used as experimental objects currently. To compare dynamic mechanical performance of these two materials, this study performed dynamic compression test with five different strain rates on concrete and rock using Split Hopkinson Pressure Bar (SHPB) to obtain basic dynamic mechanical parameters of them and then summarized the relationship of dynamic compressive strength, peak strain and strain rate of two materials. Moreover, specific energy absorption is introduced to confirm dynamic damage mechanisms of concrete and rock materials. This work can not only help to improve working efficiency to the largest extent but also ensure the smooth development of engineering, providing rich theoretical guidance for development of related engineering in the future.

The testing undertaken for this dissertation is intended to help quantify the various time-dependant deformation processes around typical deep level hard rock tabular excavations. Three mechanisms were investigated and two different hard rock types, Ventersdorp Lava and Elsburg Quartzite were used. Uniaxial compression creep studies were done as the first part of the study followed by shear creep studies on discontinuities where crushed lava and crushed quartzite as well as a natural gouge were used as infilling. An important conclusion made is that the relationship between grain size and infilling thickness is more important than previously might have been assumed. The last part of the study consisted of triaxial post-failure relaxation tests. As far as could be determined, this is the first time triaxial post-failure tests were attempted, particularly on typical South African hard rocks. An important finding of this study is that during compression creep as well as during triaxial post-failure relaxation the amount of energy dissipated for the lava is significantly less than for quartzite. For mines operating at great depth (more than 2000m) the implication is that the rock material might relax much more slowly than might have been assumed and this means that after failure the rock mass continues to store large amounts of strain energy. This study provides the first data available for energy change calculations in fractured rock masses. Three mechanisms of time-dependant deformation were quantified providing valuable data for numerical investigations.
Dissertation (MSc (Mine Strata Control))--University of Pretoria, 2006.
Mining Engineering
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