Research Advances in the Interaction among Stratum-Ground Fissure-Tunnel under Subway Dynamic Loading

2012 ◽  
Vol 226-228 ◽  
pp. 1513-1516 ◽  
Author(s):  
Li Qun Yuan ◽  
Hong Jia Liu ◽  
Yu Ming Men

Ground fissure is a kind of serious geological disaster. There will be more unprecedented challenges during the construction of the urban subway in ground fissures-developed zone. How to ensure the long-term operation safety of the subway crossing ground fissure belts are the first problems for the subway under construction in the cities with ground fissure developed. One of the important problems is that dynamic interaction and disaster effect control among ground fissure-stratum-subway tunnel under subway dynamic loading, which is also the important problem to be solved in the engineering. This problem involves the following three aspects: (a) the determination of subway dynamic loading; (b) the structure dynamic response of subway tunnel; (c) the interaction among stratum-ground fissure-subway tunnel. According to make a comment on these researches, some issues which are necessary to carry out in this field are suggested.

Author(s):  
Karel Matocha

The assessment of the residual lifetime of critical components of industrial plants requires the knowledge of mechanical properties prior to operation, respecting all technological operations realized throughout the manufacture of the component, and the knowledge of mechanical properties after actual time of operation (actual mechanical properties). Small Punch (SP) test technique enables measurement of the realistic material properties at the critical locations in the component both prior and after long-term operation. The paper shows the examples of the sampling of testing material from the critical components of the industrial plants and the procedures for determination of tensile and fracture characteristics by SP tests at ambient and low temperatures. The special attention is devoted to the test specimen orientation for determination of SP fracture energy ESP.


Author(s):  
Ivan Klevtsov ◽  
Andrei Dedov

Long-term operation of the power plant components in the conditions of the creep leads to the degradation of the short-term mechanical properties of the material. Therefore, in order to predict the degree of the metal degradation and integrity of the component the determination of the mechanical properties of the actual component in service material is required. Since the standard tests requiring a significant volume of sample material cannot be applied the technique of the tensile testing of miniature flat plate specimens has been developed in Tallinn University of Technology and described in this paper. The results of the tests of miniature flat plate specimens have been compared with testing results of cylindrical specimens with standard size and at the same time the comparison has shown a good agreement of the results. The data analysis has also shown the high repeatability of the tests results of miniature specimens. Thus, the developed technique of the miniature flat plate specimens testing could be considered as accurate and reliable method and could be definitely used for evaluation of the tensile properties of the metal.


2020 ◽  
pp. 32-42
Author(s):  
V. N. Gadalov ◽  
S. V. Safonov ◽  
E. A. Filatov ◽  
O. N. Boldyreva ◽  
I. A. Makarova

The studies of the dependence of acoustic characteristics on the microstructure of chromium-molybdenum-vanadium steels in various structural states after long term operation are presented. The meaning of the acoustic limit state criterion, which represents a relative assessment of accumulated structural damage of the long run metal for the time delay of ultrasonic Rayleigh waves and determination of the limit state of the material, is revealed. It is established that at the acoustic criterion of the limit state of ≥0.7, the metal is in the state of avalanche creep and reaches the limit state. Measurements of acoustic characteristics gave a good agreement with the results of metallographic studies conducted on sections of metal cuttings. In addition, the criterion was tested when diagnosing technical devices made of steel 15X1M1F, 12X2MFSR, 17GS, 09G2S.


Author(s):  
Alexander Arzhaev ◽  
Kirill Arzhaev ◽  
Sergey Butorin ◽  
Ilya Denisov ◽  
Maxim Konstantinov

The paper considers provision of strength and structural integrity for safety relevant passive NPP components - pipelines and equipment - in long-term operation of NPP units. The methods of determining the actual load parameters during equipment installation, adjustment and commissioning are considered. The application of the acoustoelasticity method, which provides measurement of mechanical stresses arising as a result of technological operations, will allow to identify implicit installation preloads and assess their impact on ensuring the design life of pipeline systems, including the equipment installed. Recommendations are given for application of the acoustoelasticity method on NPP units under construction as a fist priority. At the objects of application of the acoustoelasticity method for the construction of the Unit1 of Kursk NPP-2, noted above (ECCS, CS, steam and feed water pipelines), at the present time, in accordance with the certified measurement procedure (CMP), it is possible to reveal implicit installation preloads only at temperatures not higher than 55ºC. Monitoring the actual load level in the "as built" state will be a reliable guarantee of safe operation of Kursk NPP-2 pipelines according to the criteria of strength and structural integrity.


Author(s):  
Olena Yaremenko

Abstract. Problem. In this article we offer the meth-odology of calculation, based on the idea of dismem-berment of vault on the separate archs of single width. It is recommended for the estimation of efforts in the designed and damaged vaults. Also offered a methods of calculation effort in serried vaults. As spatial inflexibility of cross vault below than inflexi-bility of serried vault, then it is necessary to execute the calculation of the cheek arch abstracted from the tray of cross vault also. If the outline of tray is exe-cuted on a circular curve, then it is possible to take methodology of calculation of archs with the outline of axis a curve as catenoid. Goal. The proposed methodology for calculating closed and cross vaults is also based on the idea of dividing the arch into separate arches of unit width. The results of studies of efforts and rational forms of arches of V.A. Kiselev [1]. Methodology. Calculation based on the idea of dismemberment of vault on the separate archs of single width. Recommended for the estimation of efforts in the designed and damaged vaults. A method over of calculation of dome is brought for determina-tion of effort in serried vaults. Results. At the choice of outline of axis of arch it is necessary aspires to that an axis, on possibility, coincided with the curve of pressure. Such outline of axis is rational, as there are only central forces of N in an arch. Flexion mo-ments M and transversal forces of Q are equal to the zero. The coincidence of axis of arch with the curve of pressure can be got for the three-hinged arch. For the statically undetermined arch of complete coinci-dence of axis with the curve of pressure attaining is impossible, so that the origin of flexion moments at any her outline is inevitable. Originality. The tech-nique based on the separation of flat elements from the spatial structure does not show the reserves of strength of the structure. Experience of long-term operation of vaulted structures designed or verified by calculation using similar methods [2], [9] shows caution and reliability. Practical value. The tech-nique is also suitable for assessing the strength of damaged vaults with collapsed corners or walms.


2015 ◽  
pp. 86-91
Author(s):  
I. Yu. Bykov ◽  
I. N. Birillo ◽  
P. A. Kuzbozhev

During operation the technological pipelines of gas-distributing station are affected by mechanical static loading resulted from internal pressure of gas in the high pressure pipelines and a dynamic loading from a high-speed stream of gas in low pressure pipelines. A comparison is made of characteristics of mechanical properties of gas-distributing station pipes metal after a long-term operation for the conditions of static and dynamic loading effects.


2011 ◽  
Vol 250-253 ◽  
pp. 2342-2345 ◽  
Author(s):  
Yang Liu ◽  
Kai Ling Li ◽  
Yu Ming Men ◽  
Guang Yuan Weng ◽  
Hong Jia Liu

The interaction mechanism, between soil and U-shaped Subway tunnel, is studied by numerical simulation in the environment of ground fissures. The Subway Line 2 through the ground fissures in Xi’an. The analysis results show that the soil mass influenced by the relative displacement and the vertical displacement gradually increases with the relative displacement increasing of ground fissures movement. The deformation area of tunnel lies in the two sides of presupposed ground fissure, and the area enlarge with vertical relative displacement increasing. The tunnel structure damages at the ground fissures when the relative displacement reaches to 100mm. The footwall part is in tension and the hanging wall part is under pressure on the top of tunnel structure at the ground fissure. The footwall part is under pressure and the hanging wall part is in tension on the bottom of tunnel structure at the ground fissure. In the practical projects, the sectional type tunnel should be employed when the Subway tunnel through the ground fissures.


2021 ◽  
Author(s):  
Michal Šnírer ◽  
Kristína Krištofová ◽  
Gabriel Farkas ◽  
Peter Hausner ◽  
Vladimír Slugeň
Keyword(s):  

2006 ◽  
Vol 160 (1) ◽  
pp. 440-445 ◽  
Author(s):  
Ho Kim ◽  
Se-Jong Shin ◽  
Young-gil Park ◽  
Joohan Song ◽  
Hee-tak Kim
Keyword(s):  

2013 ◽  
Vol 203-204 ◽  
pp. 121-124 ◽  
Author(s):  
Monika Gwoździk ◽  
Zygmunt Nitkiewicz

The paper presents results of X-ray measurements of the texture of a magnetite (Fe3O4) layer formed on 10CrMo9-10 steel during 100,000 hours operation at the temperature of 575°C (in a flowing medium environment). The formed oxide layer was ≈140µm thick. Measurements of texturing were performed on the oxide surface and also at the depth of ≈50µm from the surface (1st polishing) and ≈100µm (2nd polishing). X-ray studies were carried out using the radiation of a cobalt anode tube, λCo=0.17902nm, for (311) and (400) Fe3O4 reflections, using a radiation beam collimated to φ=2mm. The study was aimed at determination of correlation between the texturing and the structure on the magnetite layer cross-section. A clear texturing of {111} and {111} type for the magnetite in the initial state and after the second polishing was found. Instead, after the first polishing there was a substantial texturing of {034} and {015} type. A different nature of the texture may result from a diversified morphology of magnetite at various depths (caused inter alia by a differentiated temperature on the tube wall cross-section during the material operation), which is related among other things to the crystallites size. The magnetite structure and texture changes can affect the magnetite porosity and cleavage.


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