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Supports
Published in Ratan Raj Tatiya, Surface and Underground Excavations, 2013
Use of the in-situ rock to support the rock is the best way of designing supporting system wherever feasible. A competent rock is defined as the rock, which, because of its physical and geological characteristics, is capable of sustaining openings without any heavy structural supports.12 Rock mechanics tests are performed to evaluate the structural properties of the in situ rocks. If the rock is to support effectively it must not be allowed to loosen. This, in turn, requires a careful blasting and selection of properly shaped openings. The size should be kept as minimum as possible. Adherence to these practices could prove a useful guideline to minimize the need of artificial supports.
Survey based open pit wall monitoring — Experience based realities
Published in T. Szwedzicki, Geotechnical Instrumentation and Monitoring in Open Pit and Underground Mining, 2020
A.M. Lang, C.F. Swindells, G.J. Higham
The geology and weathering and/or alteration profile will control the variation in rock strength or competence of the intact rock substance. Weathering and alteration can result in significant lateral and vertical variability in strength and the presence of material prone to slaking, swelling or progressive degradation.
Rocks and rock minerals
Published in Ivan Gratchev, Rock Mechanics Through Project-Based Learning, 2019
Crystalline rocks with low porosity prove to be more competent and stronger rock types compared to sedimentary rocks with a clastic texture. However, crystalline rocks (e.g., granite) can be more susceptible to weathering.
Performance Evaluation of Voltage Ripple-Based Passive Islanding Detection Method for a Single-Phase Utility-Connected Micro-Grid System
Published in IETE Journal of Research, 2023
Rahul S. Somalwar, Diksha A. Shinde, S.G. Kadwane
The paper has assessed the performance of passive IDM based on ripples in voltage for a micro-grid system connected single-phase utility grid in islanding and non-islanding situations. The method uses ripple content of voltage at PCC, with specific threshold value and delay time for islanding detection. The method is demonstrated for different load provision on MATLAB/SIMULINK software and prototype experimental set up and it is found that the method is reliable, computationally inexpensive, and robust with reduced NDZ. It is able to detect islanding within 0.3 sec, which is in permissible limit applied by IEEE 1547 standard. This technique is competent to differentiate between islanding and any other scenario like a fault. Voltage ripple-based passive IDM can be used appropriately in a single-phase utility-connected micro-grid system.
Effect of soaking time on the geotechnical behavior for different types of sedimentary rocks in Egypt
Published in HBRC Journal, 2022
Water–rock interactions can significantly deteriorate the physical and mechanical properties of sedimentary rocks, and this has been identified as one of the serious issues influencing the stability and safety of structures in civil engineering, such as foundations subject to underground seepage from continuous surface irrigation. In the current study, the properties of sedimentary rocks examined at three water-contact conditions, natural state, after 48 h and after 30 days of soaking, have been studied. The results show that with increasing soaking time, the elastic modulus and the unconfined compressive strength decreased for all the sedimentary rock samples investigated in this study. Both sandstone and limestone found to be dissolute in water. However, the drop in sandstone stress–strain is much more significant compared to the dolomitic limestone. Dolomitic limestone is more resisting and durable to deterioration when submerged in freshwater compared to the sandstone samples, and it depends on the dolomite percent in it. Moreover, the most competent and stable sandstone sample is S10 (deep brown color) and the second best is S5 (purple color) due to the presence of iron oxide that gives the rock more stiffness than other sandstone samples. However, for the dolomitic limestone samples, the most competent and stable sample is S11 (dark gray) and the second best is S12 (dark gray).
Preservation of the Cadia Valley porphyry Au–Cu district, NSW, Australia: Silurian basin formation and subsequent inversion
Published in Australian Journal of Earth Sciences, 2021
M. Groome, R. M. Tosdal, A. C. Harris, I. G. Percival
Shortening in the Forest Reefs Volcanics and Cadia Intrusive Complex was accommodated on moderate-to-steeply dipping faults, including those of the Gibb and Cadiangullong fault systems, and the northeast-striking Powerline, Copper Gully, and Cat faults (Figure 4a). Basement fault blocks composed of massive volcaniclastic and intrusive rocks preserve little evidence for deformation outside discrete fault zones, and thus behaved as relatively rigid blocks during thick-skinned shortening strain. In the overlying Waugoola Group, shortening linked to slip on the basement faults was accommodated by a variety of thin-skin structures, including faults, folds and slip along bedding planes or along the basal unconformity. The differences in deformation style reflects rheological contrasts between competent basement rocks and the bedded cover rocks.