Acta Polytechnica. 2016, vol. 56, no. 6http://hdl.handle.net/10467/666182024-03-29T00:42:12Z2024-03-29T00:42:12ZEVALUATION OF THE SURFACE SETTLEMENT ABOVE THE PRAGUE METRO LINE A EXTENSION CONSTRUCTED BY TWO SHIELDSHilar , MatousTuan The, Nhuhttp://hdl.handle.net/10467/672942017-02-09T11:41:01Z2016-01-01T00:00:00ZEVALUATION OF THE SURFACE SETTLEMENT ABOVE THE PRAGUE METRO LINE A EXTENSION CONSTRUCTED BY TWO SHIELDS
Hilar , Matous; Tuan The, Nhu
The new section of the Prague metro V.A is located in the west part of Prague, between stations Dejvická and Motol Hospital. The new metro section is 6.2km long and has four new stations. Majority of the two running tunnels that are 6.2km long were excavated by two EPB (Earth Pressure Balance) shields (2 × 4.8 km), it was the first use of modern tunnelling machines in the Czech Republic. Surface settlement above the running tunnels caused by the EPB shields was regularly monitored. The following paper is focused on an evaluation of the mentioned surface settlement using a volume loss. Consequently, numerical modelling of various cross-sections was executed. Modelling was realised by a finite element method in 2D, using the software Plaxis. Two different approaches were applied for modelling of the 3D effect in 2D. Important parameters Mstage and Cref were derived for the selected cross-sections by back analyses (comparison of the numerical modelling results with the results of monitoring). The results of realised numerical modelling and the volume loss evaluation can be used for a preparation and realisation of similar tunnels in similar geology (for example, construction of the Prague metro line D, which will probably also be excavated by the EPB shields).
2016-01-01T00:00:00ZITINERARIES INDUCED BY EXCHANGE OF THREE INTERVALSMasáková , ZuzanaPelantová , EditaStarosta , Štěpánhttp://hdl.handle.net/10467/672932017-02-09T11:40:46Z2016-01-01T00:00:00ZITINERARIES INDUCED BY EXCHANGE OF THREE INTERVALS
Masáková , Zuzana; Pelantová , Edita; Starosta , Štěpán
We focus on a generalization of the three gap theorem well known in the framework of exchange of two intervals. For the case of three intervals, our main result provides an analogue of this result implying that there are at most 5 gaps. To derive this result, we give a detailed description of the return times to a subinterval and the corresponding itineraries.
2016-01-01T00:00:00ZMAGNETRON SPUTTERING WITH HOT SOLID TARGET: THERMAL PROCESSES AND EROSIONBorduleva Olegovna, AlenaBleykher Alekseevna, GalinaSidelev Vladimirovich, DmitriiKrivobokov Pavlovich, Valeriyhttp://hdl.handle.net/10467/672922017-02-09T11:40:43Z2016-01-01T00:00:00ZMAGNETRON SPUTTERING WITH HOT SOLID TARGET: THERMAL PROCESSES AND EROSION
Borduleva Olegovna, Alena; Bleykher Alekseevna, Galina; Sidelev Vladimirovich, Dmitrii; Krivobokov Pavlovich, Valeriy
This work focuses on erosion and thermal processes taking place on the surface of the titanium target in magnetron sputtering. The study was carried out using magnetron sputtering systems (MSS) with different thermal insulation target types from the magnetron body. It was found that the presence of an evaporation component allows the rate of removal of atoms from the surface of a solid target to be increased with limited thermal conduction. A mathematical simulation was used to evaluate the contribution of evaporation to the increase in the coating deposition rate for complete and partial thermal insulation. It was found that non-uniformity of the direct-axis component of the magnetic induction vector helps to localize the heating. also increases the evaporation rate on the surface of the target. It was proved that local evaporation including sublimations on the surface of a hot target is a significant factor in increasing the coating deposition rate. Due to this mechanism, the coating deposition rate can be increased 5 times for Ti in comparison with fully cooled targets. This result can be applied for direct current magnetrons and also for pulsed systems. It was also found that evaporation increased the energy efficiency of the target erosion. The most suitable metals were selected for obtaining high-intensity emission of atoms from a solid target.
2016-01-01T00:00:00ZCONSTITUTIVE MODEL OF STEEL FIBRE REINFORCED CONCRETE SUBJECTED TO HIGH TEMPERATURESBlesak , LukasGoremikins , VadimsWald , FrantisekSajdlova , Terezahttp://hdl.handle.net/10467/672912017-02-09T11:40:26Z2016-01-01T00:00:00ZCONSTITUTIVE MODEL OF STEEL FIBRE REINFORCED CONCRETE SUBJECTED TO HIGH TEMPERATURES
Blesak , Lukas; Goremikins , Vadims; Wald , Frantisek; Sajdlova , Tereza
Research on structural load-bearing systems exposed to elevated temperatures is an active topic in civil engineering. Carrying out a full-size experiment of a specimen exposed to fire is a challenging task considering not only the preparation labour but also the necessary costs. Therefore, such experiments are simulated using various software and computational models in order to predict the structural behaviour as exactly as possible. In this paper such a procedure, focusing on software simulation, is described in detail. The proposed constitutive model is based on the stress-strain curve and allows predicting SFRC material behaviour in bending at ambient and elevated temperature. SFRC material is represented by the initial linear behaviour, an instantaneous drop of stress after the initial crack occurs and its consequent specific ductility, which influences the overall modelled specimen behaviour under subjected loading. The model is calibrated with ATENA FEM software using experimental results.
2016-01-01T00:00:00Z