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Stress state rock mass monitoring ahead of longwall No. II/501/C, Mine Staszic-Wujek, PGG, Poland -Project RFCS DD-MET
Waclawik, Petr ; Kukutsch, Radovan ; Staš, Lubomír ; Souček, Kamil ; Vavro, Leona ; Vavro, Martin ; Kubina, Lukáš ; Schuchová, Kristýna
For designing precisely the reinforcement of mine gate and reinforcing underground structures in general, knowing stress and deformation states in the rock massive in the immediate vicinity of these mine works as precisely as possible is absolutely decisive. In order to verify the rock mass stress state and its changes induced by longwall mining, the monitoring of rock mass stress changing in connection with the mine out of the coal seam No. 501, longwall face No. II/501/C in the Mine Staszic-Wujek, Poland, was suggested. The aim of the contractual research was the realisation and interpretation of the rock stress state monitoring using the CCBO (Compact Conical ended Borehole Overcoring method) and CCBM (Compact Conical ended Borehole Monitoring method) probes in the forefield of mentioned longwall face within geotechnical station. To verify stress monitoring, the survey of the state of the longwall gate was carried out using a pulse 3D scanner. The purpose was to capture deformation changes ahead of the advancing longwall face, specifically, at five stages in the ± 20 m section on each side from the installed geotechnical station.
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Design of manufacturing simulations of a flatplate pulsating heat pipe
Pontecorvo, Matteo
Currently, a research team in the University of Brighton, in collaboration with the European Space Agency (ESA), is developing a pulsating heat pipe that will eventually be launched and tested in space, with the International Space Station (ISS) as destination, for research into passive thermal devices and their behaviour in a vacuum. The approved pulsating heat pipe design incorporates one titanium plate, which is classified as a metal, and one aluminum-oxide sapphire plate that is classified as a ceramic. At the moment, the team is faced with the challenge of bonding the two plates together since, using convectional manufacturing methods, the parts fail due to the high level of induced stress. A research into manufacturing processes to bond together titanium and sapphire is essential to ensure that the final device will operate for several weeks (maybe even months) without leaking and the need for maintenance. The project explores potential manufacturing processes aimed to bond together these materials and subsequently propose a solution. Furthermore, static and thermal analyses are carried out with the aid of SolidWorks to exploit potential points of failure due to stress concentrations induced by cooling after bonding. The results indicate that both titanium and sapphire are capable of sustaining the induced stresses but, due to the complex geometry of the pulsating heat pipe at the contact surface, the bonding agent is likely to fail due to the induced stresses.
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Measurement of Tensor Stress Changes by Conical Gauge Probe in Ostrava-Karvina Coal Basin
Staš, Lubomír ; Souček, Kamil ; Knejzlík, Jaromír ; Waclawik, P. ; Palla, L.
A device designed on base of measurement local deformations on compact conical ended borehole was used for long term monitoring of stress changes induced by closed underground human activity.The changes of stress state of rock mass impacted by progress of long-wall were investigated. This experiment demonstrated that monitored strain changes on borehole bottom are formed both by geomechanical situation based on a progress of long-wall and perhaps by local geomechanical situation based on stress redistribution after boring of measuring borehole and on plastic deformation of creeping rock material.
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